ADM1026 D

ADM1026
Complete Thermal System
Management Controller
The ADM1026 is a complete system hardware monitor for
microprocessor-based systems, providing measurement and limit
comparison of various system parameters. The ADM1026 has up to 19
analog measurement channels. Fifteen analog voltage inputs are
provided, five of which are dedicated to monitoring +3.3 V, +5.0 V,
and 12 V power supplies, and the processor core voltage. The
ADM1026 can monitor two other power supply voltages by
measuring its own VCC and the main system supply. One input (two
pins) is dedicated to a remote temperature-sensing diode. Two
additional pins can be configured as general-purpose analog inputs to
measure 0 V to 2.5 V, or as a second temperature sensing input. The
eight remaining inputs are general-purpose analog inputs with a range
of 0 V to 2.5 V or 0 V to 3.0 V. The ADM1026 also has an on-chip
temperature sensor.
The ADM1026 has eight pins that can be configured for fan speed
measurement or as general-purpose logic I/O pins. Another eight pins are
dedicated to general-purpose logic I/O. An additional pin can be
configured as a general-purpose I/O or as the bidirectional THERM pin.
Measured values can be read out via a 2-wire serial system
management bus, and values for limit comparisons can be
programmed over the same serial bus. The high speed, successive
approximation ADC allows frequent sampling of all analog channels
to ensure a fast interrupt response to any out-of-limit measurement.
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LQFP−48
CASE 932
MARKING DIAGRAM
ADM1026
JSTZ
#YYWW
1
Features
 Up to 19 Analog Measurement Channels














(Including Internal Measurements)
Up to 8 Fan Speed Measurement Channels
Up to 17 General-Purpose Logic I/O Pins
Remote Temperature Measurement with Remote Diode (Two Channels)
On-Chip Temperature Sensor
Analog and PWM Fan Speed Control Outputs
2-Wire Serial System Management Bus (SMBus)
8 kB On-Chip EEPROM
Full SMBus 1.1 Support Includes Packet Error Checking (PEC)
Chassis Intrusion Detection
Interrupt Output (SMBAlert)
Reset Input, Reset Outputs
Thermal Interrupt (THERM) Output
Limit Comparison of All Monitored Values
This is a Pb-Free Device*
ADM1026JSTZ = Special Device Code
#
= Pb-Free Package
YYWW
= Date Code
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 54 of this data sheet.
Applications
 Network Servers and Personal Computers
 Telecommunications Equipment
 Test Equipment and Measuring Instruments
*For additional information on our Pb-Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting
Techniques Reference Manual, SOLDERRM/D.
 Semiconductor Components Industries, LLC, 2012
April, 2012 − Rev. 4
1
Publication Order Number:
ADM1026/D
ADM1026
GPIO10
GPIO11
GPIO12
GPIO13
GPIO14
GPIO15
GPIO16/THERM
AIN0(0V – 3V)
AIN1(0V – 3V)
AIN2(0V – 3V)
AIN3(0V – 3V)
AIN4(0V – 3V)
48
47
46
45
44
43
42
41
40
39
38
37
PIN ASSIGNMENT
GPIO9
1
36
AIN5(0V – 3V)
GPIO8
2
35
AIN6(0V – 2.5V)
FAN0/GPIO0
3
34
AIN7(0V – 2.5V)
FAN1/GPIO1
4
33
+VCCP
FAN2/GPIO2
5
32
+12 VIN
FAN3/GPIO3
6
31
–12 VIN
3.3V MAIN
7
30
+5 VIN
DGND
8
29
VBAT
FAN4/GPIO4
9
28
D2+/AIN8(0V – 2.5V)
FAN5/GPIO5 10
27
D2–/AIN9(0V – 2.5V)
FAN6/GPIO6 11
26
D1+
FAN7/GPIO7 12
25
D1-/NTESTIN
PIN 1
ADM1026
VREF 24
DAC 23
3.3V STBY 22
AGND 21
RESETMAIN 20
RESETSTBY 19
PWM 18
INT 17
CI 16
ADD/NTESTOUT 15
SCL 13
SDA 14
TOP VIEW
ADD/ NTESTOUT SDA
3.3V MAIN
SCL 3.3V STBY
VCC
RESET IN
GPIO15
GPIO14
3.3V MAIN
RESET
GENERATOR
GPIO13
GPIO12
SERIAL BUS
INTERFACE
GPIO
REGISTERS
GPIO11
GPIO10
RESETMAIN
VCC
100k
GPIO9
GPIO8
VCC
FAN 7/GPIO7
FAN 6/GPIO6
3.3V STBY
RESET
GENERATOR
RESETSTBY
PWM REGISTER
AND CONTROLLER
FAN 5/GPIO5
FAN
SPEED
COUNTER
FAN 4/GPIO4
FAN 3/GPIO3
FAN 2/GPIO2
VALUE AND
LIMIT
REGISTERS
FAN 1/GPIO1
ADDRESS
POINTER
REGISTER
FAN 0/GPIO0
VBAT
+5 VIN
LIMIT
COMPARATORS
8k BYTES
EEPROM
–12 VIN
+12 VIN
INTERRUPT
STATUS
REGISTERS
AUTOMATIC
FAN SPEED
CONTROL
+VCCP
AIN0 (0V - +3V)
INT MASK
REGISTERS
AIN1 (0V - +3V)
AIN2 (0V - +3V)
INPUT
ATTENUATORS
AND
ANALOG
MULTIPLEXER
AIN3 (0V - +3V)
AIN4 (0V - +3V)
AIN5 (0V - +3V)
AIN6 (0V - +2.5V)
INTERRUPT
MASKING
100k
INT
CONFIGURATION
REGISTERS
D2–/AIN9 (0V - +2.5V)
BAND GAP
REFERENCE
ANALOG
OUTPUT REGISTER
AND 8−BIT DAC
BAND GAP
TEMPERATURE
SENSOR
DGND
VREF (1.82V OR 2.5V)
Figure 1. Functional Block Diagram
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2
VCC
GPIO16/THERM
D2+/AIN8 (0V - +2.5V)
AGND
CI
100k
8−BIT
ADC
D1–/NTESTIN
VCC
ADM1026
AIN7 (0V - +2.5V)
D1+
PWM
TO GPIO
REGISTERS
DAC
ADM1026
Table 1. ABSOLUTE MAXIMUM RATINGS
Parameter
Rating
Unit
Positive Supply Voltage (VCC)
6.5
V
Voltage on +12 VIN Pin
+20
V
Voltage on −12 VIN Pin
−20
V
Voltage on Analog Pins
−0.3 to (VCC + 0.3)
V
−0.3 to +6.5
V
Input Current at Any Pin
5
mA
Package Input Current
20
mA
Voltage on Open-drain Digital Pins
Maximum Junction Temperature (TJMAX)
150
C
Storage Temperature Range
−65 to +150
C
Lead Temperature, Soldering
Vapor Phase (60 sec)
Infrared (15 sec)
215
200
ESD Rating
−12 VIN Pin
All Other Pins
1000
2000
C
V
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
NOTE: This device is ESD sensitive. Use standard ESD precautions when handling.
Table 2. THERMAL CHARACTERISTICS
Package Type
48-lead LQFP
qJA
qJC
Unit
50
10
C/W
Table 3. PIN ASSIGNMENT
Pin No.
Mnemonic
Type
1
GPIO9
Digital I/O†
General-purpose I/O pin that can be configured as digital inputs or outputs.
Description
2
GPIO8
Digital I/O†
General-purpose I/O pin that can be configured as digital inputs or outputs.
3
FAN0/GPIO0
Digital I/O
Fan tachometer input with internal 10 kW pullup resistor to 3.3 V STBY. Can be
reconfigured as a general-purpose, open drain, digital I/O pin.
4
FAN1/GPIO1
Digital I/O
Fan tachometer input with internal 10 kW pullup resistor to 3.3 V STBY. Can be
reconfigured as a general-purpose, open drain, digital I/O pin.
5
FAN2/GPIO2
Digital I/O
Fan tachometer input with internal 10 kW pullup resistor to 3.3 V STBY. Can be
reconfigured as a general-purpose, open drain, digital I/O pin.
6
FAN3/GPIO3
Digital I/O
Fan tachometer input with internal 10 kW pullup resistor to 3.3 V STBY. Can be
reconfigured as a general-purpose, open drain, digital I/O pin.
7
3.3 V MAIN
Analog Input
8
DGND
Ground
9
FAN4/GPIO4
Digital I/O
Fan tachometer input with internal 10 kW pullup resistor to 3.3 V STBY. Can be
reconfigured as a general-purpose, open drain, digital I/O pin.
10
FAN5/GPIO5
Digital I/O
Fan tachometer input with internal 10 kW pullup resistor to 3.3 V STBY. Can be
reconfigured as a general-purpose, open drain, digital I/O pin.
11
FAN6/GPIO6
Digital I/O
Fan tachometer input with internal 10 kW pullup resistor to 3.3 V STBY. Can be
reconfigured as a general-purpose, open drain, digital I/O pin.
12
FAN7/GPIO7
Digital I/O
Fan tachometer input with internal 10 kW pullup resistor to 3.3 V STBY. Can be
reconfigured as a general-purpose, open drain, digital I/O pin.
13
SCL
Digital Input
Monitors the main 3.3 V system supply. Does not power the device.
Ground pin for digital circuits.
Open Drain Serial Bus Clock. Requires a 2.2 kW pullup resistor.
14
SDA
Digital I/O
15
ADD/NTESTOUT
Digital Input
This is a three-state input that controls the two LSBs of the serial bus address. It
also functions as the output for NAND tree testing.
16
CI
Digital Input
An active high input that captures a chassis intrusion event in Bit 6 of Status
Register 4. This bit remains set until cleared, as long as battery voltage is applied
to the VBAT input, even when the ADM1026 is powered off.
Serial Bus Data. Open drain I/O. Requires a 2.2 kW pullup resistor.
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3
ADM1026
Table 3. PIN ASSIGNMENT
Pin No.
Mnemonic
Type
17
INT
Digital Output
Interrupt Request (Open Drain). The output is enabled when Bit 1 of the
configuration register is set to 1. The default state is disabled. It has an on-chip
100 kW pullup resistor.
Description
18
PWM
Digital Output
Open drain pulse width modulated output for control of the fan speed. This pin
defaults to high for the 100% duty cycle for use with NMOS drive circuitry. If a
PMOS device is used to drive the fan, the PWM output may be inverted by setting
Bit 1 of Test Register 1 = 1.
19
RESETSTBY
Digital Output
Power-on Reset. 5 mA driver (weak 100 kW pullup), active low output (100 kW
pullup) with a 180 ms typical pulse width. RESETSTBY is asserted whenever
3.3 V STBY is below the reset threshold. It remains asserted for approximately
180 ms after 3.3 V STBY rises above the reset threshold.
20
RESETMAIN
Digital I/O
Power-on Reset. 5 mA driver (weak 100 kW pullup), active low output (100 kW
pullup) with a 180 ms typical pulse width. RESETMAIN is asserted whenever 3.3 V
MAIN is below the reset threshold. It remains asserted for approximately 180 ms
after 3.3 V MAIN rises above the reset threshold. If, however, 3.3 V STBY rises with
or before 3.3 V MAIN, then RESETMAIN remains asserted for 180 ms after
RESETSTBY is deasserted. Pin 20 also functions as an active low RESET input.
21
AGND
Ground
22
3.3 V STBY
Power Supply
Supplies 3.3 V power. Also monitors the 3.3 V standby power rail.
23
DAC
Analog Output
0 V to 2.5 V output for analog control of the fan speed.
24
VREF
Analog Output
Reference Voltage Output. Can be selected as 1.8 V (default) or 2.5 V.
25
D1–/NTESTIN
Analog Input
Connected to a cathode of the first remote temperature sensing diode. If it is held
high at power-on, it activates the NAND tree test mode.
26
D1+
Analog Input
Connected to the anode of the first remote temperature sensing diode.
27
D2–/AIN9
Programmable
Connected to the cathode of the second remote temperature sensing diode or the
analog input may be reconfigured as a 0 V − 2.5 V analog input.
28
D2+/AIN8
Programmable
Connected to the anode of the second remote temperature sensing diode, or the
analog input may be reconfigured as a 0 V − 2.5 V analog input.
29
VBAT
Analog Input
Monitors battery voltage, nominally +3.0 V.
30
+5.0 VIN
Analog Input
Monitors the +5.0 V supply.
31
−12 VIN
Analog Input
Monitors the −12 V supply.
32
+12 VIN
Analog Input
Monitors the +12 V supply.
33
+VCCP
Analog Input
Monitors the processor core voltage (0 V to 3.0 V).
34
AIN7
Analog Input
General-purpose 0 V to 2.5 V analog inputs.
35
AIN6
Analog Input
General-purpose 0 V to 2.5 V analog inputs.
36
AIN5
Analog Input
General-purpose 0 V to 3.0 V analog inputs.
37
AIN4
Analog Input
General-purpose 0 V to 3.0 V analog inputs.
38
AIN3
Analog Input
General-purpose 0 V to 3.0 V analog inputs.
39
AIN2
Analog Input
General-purpose 0 V to 3.0 V analog inputs.
40
AIN1
Analog Input
General-purpose 0 V to 3.0 V analog inputs.
41
AIN0
Analog Input
General-purpose 0 V to 3.0 V analog inputs.
42
GPIO16/THERM
Digital I/O†
General-purpose I/O pin that can be configured as a digital input or output. Can
also be configured as a bidirectional THERM pin (100 kW pullup).
43
GPIO15
Digital I/O†
General-purpose I/O pin that can be configured as a digital input or output.
44
GPIO14
Digital I/O†
General-purpose I/O pin that can be configured as a digital input or output.
GPIO13
Digital I/O†
General-purpose I/O pin that can be configured as a digital input or output.
46
GPIO12
Digital I/O†
General-purpose I/O pin that can be configured as a digital input or output.
47
GPIO11
Digital I/O†
General-purpose I/O pin that can be configured as a digital input or output.
48
GPIO10
Digital I/O†
General-purpose I/O pin that can be configured as a digital input or output.
45
Ground pin for analog circuits.
†GPIO pins are open drain and require external pullup resistors. Fan inputs have integrated 10 kW pullups, but these pins become open drain
when reconfigured as GPIOs.
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ADM1026
Table 4. ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VCC = VMIN to VMAX, unless otherwise noted. (Note 1, 2, and 3))
Parameter
Test Conditions/Comments
Min
Typ
Max
Unit
3.0
3.3
5.5
V
−
2.5
4.0
mA
POWER SUPPLY
Supply Voltage, 3.3 V STBY
Supply Current, ICC
Interface Inactive, ADC Active
TEMPERATURE-TO-DIGITAL CONVERTER
Internal Sensor Accuracy
−
−
3.0
C
Resolution
−
1.0
−
C
−
−
3.0
C
−
1.0
−
C
−
−
90
5.5
−
−
mA
Total Unadjusted Error (TUE) (Note 4)
−
−
2.0
%
Differential Non-linearity (DNL)
−
−
1.0
LSB
Power Supply Sensitivity
−
0.1
Conversion Time
(Analog Input or Internal Temperature) (Note 5)
−
11.38
12.06
ms
Conversion Time (External Temperature) (Note 5)
−
34.13
36.18
ms
Input Resistance (+5.0 VIN, VCCP, AIN0 − AIN5)
80
100
120
kW
Input Resistance of +12 VIN pin
70
100
115
kW
Input Resistance of −12 VIN pin
8.0
10
12
kW
Input Resistance (AIN6 − AIN9)
5.0
−
−
MW
Input Resistance of VBAT pin (Note 4)
80
100
120
kW
−
80
100
nA
−
6.0
−
nA
0
–2.5
−
V
5.0
%
External Diode Sensor Accuracy
0C < TD < 100C
Resolution
Remote Sensor Source Current
High Level
Low Level
ANALOG-TO-DIGITAL CONVERTER
(Including MUX and ATTENUATORS)
VBAT Current Drain (when measured)
CR2032 Battery Life >10 Years
VBAT Current Drain (when not measured)
%/V
ANALOG OUTPUT (DAC)
Output Voltage Range
Total Unadjusted Error (TUE)
IL = 2 mA
−
−
Zero Error
No Load
−
1.0
−
LSB
Differential Non-linearity (DNL)
Monotonic by Design
−
−
1.0
LSB
Integral Non-linearity
−
0.5
−
LSB
Output Source Current
−
2.0
−
mA
Output Sink Current
−
1.0
−
mA
1.8
2.47
1.82
2.50
1.84
2.53
V
−
0.15
−
%
−
0.15
−
%
−
25
−
mA
Output Current Source
−
2.0
−
mA
Output Current Sink
−
2.0
−
mA
REFERENCE OUTPUT
Output Voltage
Bit 2 of Register 07h = 0
Bit 2 of Register 07h = 1
Load Regulation (ISINK = 2 mA)
Load Regulation (ISOURCE = 2 mA)
Short Circuit Current
VCC = 3.3 V
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ADM1026
Table 4. ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VCC = VMIN to VMAX, unless otherwise noted. (Note 1, 2, and 3))
Parameter
Test Conditions/Comments
Min
Typ
Max
Unit
Accuracy
−
−
12
%
Full-scale Count
−
−
255
−
−
−
−
8800
4400
2200
1100
−
−
−
−
RPM
20
22.5
25
kHz
FAN RPM-TO-DIGITAL CONVERTER (Note 6)
FAN0 to FAN7 Nominal Input RPM (Note 5)
Divisor = 1, fan count = 153
Divisor = 2, fan count = 153
Divisor = 4, fan count = 153
Divisor = 8, fan count = 153
Internal Clock Frequency
OPEN DRAIN O/Ps, PWM, GPIO0 to 16
Output High Voltage, VOH
IOUT = 3.0 mA, VCC = 3.3 V
2.4
−
−
V
High Level Output Leakage Current, IOH
VOUT = VCC
−
0.1
1.0
mA
Output Low Voltage, VOL
IOUT = −3.0 mA, VCC = 3.3 V
−
−
0.4
V
−
75
−
Hz
−
−
0.4
V
140
180
240
ms
PWM Output Frequency
DIGITAL OUTPUTS (INT, RESETMAIN, RESETSTBY)
Output Low Voltage, VOL
IOUT = −3.0 mA, VCC = 3.3 V
RESET Pulse Width
OPEN DRAIN SERIAL DATABUS OUTPUT (SDA)
Output Low Voltage, VOL
IOUT = –3.0 mA, VCC = 3.3 V
−
−
0.4
V
High Level Output Leakage Current, IOH
VOUT = VCC
−
0.1
1.0
mA
Input High Voltage, VIH
2.2
−
−
V
Input Low Voltage, VIL
−
−
0.8
V
Hysteresis
−
500
−
mV
SERIAL BUS DIGITAL INPUTS (SCL, SDA)
DIGITAL INPUT LOGIC LEVELS (ADD, CI, FAN 0 to 7, GPIO 0 to 16) (Note 7 and 8)
Input High Voltage, VIH
VCC = 3.3 V
2.4
−
−
V
Input Low Voltage, VIL
VCC = 3.3 V
0.8
−
−
V
Hysteresis (Fan 0 to 7)
VCC = 3.3 V
−
250
−
mV
RESETMAIN, RESETSTBY
RESETMAIN Threshold
Falling Voltage
2.89
2.94
2.97
V
RESETSTBY Threshold
Falling Voltage
3.01
3.05
3.10
V
RESETMAIN Hysteresis
−
60
−
mV
RESETSTBY Hysteresis
−
70
−
mV
–1.0
−
−
mA
−
−
1.0
mA
−
20
−
pF
Endurance (Note 9)
100
700
−
kcycles
Data Retention (Note 10)
10
−
−
Years
−
−
400
kHz
Glitch Immunity, tSW
−
−
50
ns
Bus Free Time, tBUF
4.7
−
−
ms
Start Setup Time, tSU; STA
4.7
−
−
ms
DIGITAL INPUT CURRENT
Input High Current, IIH
VIN = VCC
Input Low Current, IIL
VIN = 0
Input Capacitance, CIN
EEPROM RELIABILITY
SERIAL BUS TIMING
Clock Frequency, fSCLK
See Figure 2 for All Parameters.
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ADM1026
Table 4. ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VCC = VMIN to VMAX, unless otherwise noted. (Note 1, 2, and 3))
Parameter
Test Conditions/Comments
Min
Typ
Max
Unit
Start Hold Time, tHD; STA
4.0
−
−
ms
SCL Low Time, tLOW
4.7
−
−
ms
SCL High Time, tHIGH
4.0
−
−
ms
SCL, SDA Rise Time, tr
−
−
1000
ns
SCL, SDA Fall Time, tf
−
−
300
ns
Data Setup Time, tSU; DAT
250
−
−
ns
Data Hold Time, tHD; DAT
300
−
−
ns
SERIAL BUS TIMING
1.
2.
3.
4.
All voltages are measured with respect to GND, unless otherwise specified.
Typicals are at TA = 25C and represent the most likely parametric norm. Shutdown current typ is measured with VCC = 3.3 V.
Timing specifications are tested at logic levels of VIL = 0.8 V for a falling edge and VIH = 2.1 V for a rising edge.
Total unadjusted error (TUE) includes offset, gain, and linearity errors of the ADC, multiplexer, and on-chip input attenuators. VBAT is accurate
only for VBAT voltages greater than 1.5 V (see Figure 14).
5. Total analog monitoring cycle time is nominally 273 ms, made up of 18 ms  11.38 ms measurements on analog input and internal
temperature channels, and 2 ms  34.13 ms measurements on external temperature channels.
6. The total fan count is based on two pulses per revolution of the fan tachometer output. The total fan monitoring time depends on the number
of fans connected and the fan speed. See the Fan Speed Measurement section for more details.
7. ADD is a three-state input that may be pulled high, low, or left open circuit.
8. Logic inputs accept input high voltages up to 5.0 V even when device is operating at supply voltages below 5.0 V.
9. Endurance is qualified to 100,000 cycles as per JEDEC Std. 22 method A117, and measured at −40C, +25C, and +85C. Typical endurance
at +25C is 700,000 cycles.
10. Retention lifetime equivalent at junction temperature (TJ ) = 55C as per JEDEC Std. 22 method A117. Retention lifetime based on activation
energy of 0.6 V derates with junction temperature as shown in Figure 15.
t LOW
tF
t HD; STA
tR
SCL
t HD; STA
t HD; DAT
t HIGH
t SU; STA
t SU; DAT
t SU; STO
SDA
P
t BUF
S
S
Figure 2. Serial Bus Timing Diagram
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P
ADM1026
TYPICAL PERFORMANCE CHARACTERISTICS
14
25
12
15
10
TEMPERATURE ERROR (5C)
TEMPERATURE ERROR (5C)
20
D+ TO GND
5
0
–5
D+ TO VCC
–10
–15
10
8
250mV
6
4
100mV
2
–20
–25
0
0
30
60
90
LEAKAGE RESISTANCE (M)
120
Figure 3. Temperature Error vs. PCB Track
Resistance
100
200
300
400
FREQUENCY (MHz)
500
600
Figure 4. Temperature Error vs. Power Supply
Noise Frequency
12
110
100mV
60mV
40mV
10
TEMPERATURE ERROR (5C)
0
100
90
80
READING (5C)
8
6
4
70
60
50
40
30
20
2
10
0
0
100
200
300
400
FREQUENCY (MHz)
500
0
600
Figure 5. Temperature Error vs. Common-mode
Noise Frequency
20
30
40 50
60
70
80
PIII TEMPERATURE (5C)
90
100 110
80
70
TEMPERATURE ERROR (5C)
0
TEMPERATURE ERROR (5C)
10
Figure 6. Pentium) III Temperature vs. ADM1026
Reading
5
–5
–10
–15
60
50
40
30
100mV
20
60mV
–20
–25
0
10
0
10
20
30
CAPACITANCE (nF)
40
0
50
Figure 7. Temperature Error vs. Capacitance
Between D+ and D–
100
40mV
200
300
400
FREQUENCY (MHz)
500
600
Figure 8. Temperature Error vs. Differential-mode
Noise Frequency
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ADM1026
TYPICAL PERFORMANCE CHARACTERISTICS
3.0
450
400
2.5
RESET TIMEOUT (ms)
350
2.0
IDD (mA)
300
250
200
1.5
1.0
150
100
0.5
50
0
–40
–20
80
20
40
60
TEMPERATURE (5C)
0
100
120
0
3.00 3.25
140
Figure 9. Powerup Reset Timeout vs. Temperature
3.50
3.75
4.00
4.25 4.50
VCC (V)
4.75
5.00
5.25 5.50
Figure 10. Supply Current vs. Supply Voltage
1.0
1.8
1.6
TEMPERATURE ERROR (5C)
TEMPERATURE ERROR (5C)
0.5
1.4
1.2
1.0
0.8
0.6
0.4
0
–0.5
–1.0
–1.5
0.2
0
0
10
20
30
40 50 60 70 80
TEMPERATURE (5C)
90
–2.0
100 110 120
Figure 11. Local Sensor Temperature Error
20
30
40 50 60 70 80
TEMPERATURE (5C)
90
100 110 120
3.5
3.0
VBAT MEASUREMENT
100
TEMPERATURE (5C)
10
Figure 12. Remote Sensor Temperature Error
120
80
60
40
20
0
0
2.5
2.0
1.5
1.0
0.5
0
2
4
6
8
10
12 14
TIME (s)
16
18
20
22 24
0
26
0
1
2
VBAT VOLTAGE
3
Figure 14. VBAT Measurement vs. Voltage
Figure 13. Response to Thermal Shock
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4
ADM1026
Functional Description
Chassis Intrusion
The ADM1026 is a complete system hardware monitor for
microprocessor-based systems. The device communicates
with the system via a serial system management bus. The
serial bus controller has a hardwired address line for device
selection (ADD, Pin 15), a serial data line for reading and
writing addresses and data (SDA, Pin 14), and an input line
for the serial clock (SCL, Pin 13). All control and
programming functions of the ADM1026 are performed over
the serial bus.
A chassis intrusion input (Pin 16) is provided to detect
unauthorized tampering with the equipment. This event is
latched in a battery-backed register bit.
Resets
The ADM1026 has two power-on reset outputs,
RESETMAIN and RESETSTBY, that are asserted when
3.3 V MAIN or 3.3 V STBY fall below the reset threshold.
These give a 180 ms reset pulse at powerup. RESETMAIN
also functions as an active-low RESET input.
Measurement Inputs
Fan Speed Control Outputs
Programmability of the analog and digital measurement
inputs makes the ADM1026 extremely flexible and
versatile. The device has an 8-bit A/D converter, and 17
analog measurement input pins that can be configured in
different ways.
Pins 25 and 26 are dedicated temperature inputs and may
be connected to the cathode and anode of a remote
temperature sensing diode.
Pins 27 and 28 may be configured as temperature inputs
and connected to a second temperature-sensing diode, or may
be reconfigured as analog inputs with a range of 0 V to 2.5 V.
Pins 29 to 33 are dedicated analog inputs with on-chip
attenuators configured to monitor VBAT, +5.0 V, −12 V,
+12 V, and the processor core voltage VCCP, respectively.
Pins 34 to 41 are general-purpose analog inputs with a
range of 0 V to 2.5 V or 0 V to 3.0 V. These are mainly
intended for monitoring SCSI termination voltages, but may
be used for other purposes.
The ADC also accepts input from an on-chip band gap
temperature sensor that monitors system ambient
temperature.
In addition, the ADM1026 monitors the supply from
which it is powered, 3.3 V STBY, so there is no need for a
separate pin to monitor the power supply voltage.
The ADM1026 has eight pins that are general-purpose
logic I/O pins (Pins 1, 2, and 43 to 48), a pin that can be
configured as GPIO or as a bidirectional thermal interrupt
(THERM) pin (Pin 42), and eight pins that can be configured
for fan speed measurement or as general-purpose logic pins
(Pins 3 to 6 and Pins 9 to 12).
The ADM1026 has two outputs intended to control fan
speed, though they can also be used for other purposes.
Pin 18 is an open drain, Pulse Width Modulated (PWM)
output with a programmable duty cycle and an output
frequency of 75 Hz. Pin 23 is connected to the output of an
on-chip, 8-bit, digital-to-analog converter with an output
range of 0 V to 2.5 V.
Either or both of these outputs may be used to implement
a temperature-controlled fan by controlling the speed of a
fan using the temperature measured by the on-chip
temperature sensor or remote temperature sensors.
Internal Registers
Table 5 describes the principal registers of the ADM1026.
For more detailed information, see Table 12 to Table 125.
Table 5. PRINCIPLE REGISTERS
Type
Description
Address
Pointer
Contains the address that selects one of
the other internal registers. When writing to
the ADM1026, the first byte of data is
always a register address, and is written to
the address pointer register.
Configuration
Registers
Sequential Measurement
When the ADM1026 monitoring sequence is started, it
cycles sequentially through the measurement of analog
inputs and the temperature sensor, while at the same time the
fan speed inputs are independently monitored. Measured
values from these inputs are stored in value registers. These
can be read over the serial bus, or can be compared with
programmed limits stored in the limit registers. The results
of out-of-limit comparisons are stored in the interrupt status
registers. An out-of-limit event generates an interrupt on the
INT line (Pin 17).
Any or all of the interrupt status bits can be masked by
appropriate programming of the interrupt mask registers.
Provide control and configuration for
various operating parameters.
Fan Divisor
Registers
Contain counter prescaler values for fan
speed measurement.
DAC/PWM
Control
Registers
Contain speed values for PWM and DAC
fan drive outputs.
GPIO
Configuration
Registers
Configure the GPIO pins as input or output
and for signal polarity.
Value and
Limit
Registers
Store the results of analog voltage inputs,
temperature, and fan speed measurements,
along with their limit values.
Status
Registers
Store events from the various interrupt
sources.
Mask
Registers
Allow masking of individual interrupt
sources.
EEPROM
The ADM1026 has 8 kB of non-volatile, electrically
erasable, programmable read-only memory (EEPROM)
from register Addresses 8000h to 9FFFh. This may be used
for permanent storage of data that is not lost when the
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ADM1026
Serial Bus Interface
ADM1026 is powered down, unlike the data in the volatile
registers. Although referred to as read-only memory, the
EEPROM can be written to (as well as read from) via the
serial bus in exactly the same way as the other registers. The
main differences between the EEPROM and other registers
are:
 An EEPROM location must be blank before it can be
written to. If it contains data, it must first be erased.
 Writing to EEPROM is slower than writing to RAM.
 Writing to the EEPROM should be restricted because
its typical cycle life is 100,000 write operations, due to
the usual EEPROM wear-out mechanisms.
Control of the ADM1026 is carried out via the serial
system management bus (SMBus). The ADM1026 is
connected to this bus as a slave device, under the control of
a master device.
The ADM1026 has a 7-bit serial bus slave address. When
the device is powered on, it does so with a default serial bus
address. The 5 MSBs of the address are set to 01011, and the
2 LSBs are determined by the logical states of Pin 15
ADD/NTESTOUT. This pin is a three-state input that can be
grounded, connected to VCC, or left open-circuit to give
three different addresses.
Table 6. ADDRESS PIN TRUTH TABLE
The EEPROM in the ADM1026 has been qualified for
two key EEPROM memory characteristics: memory cycling
endurance and memory data retention.
Endurance qualifies the ability of the EEPROM to be
cycled through many program, read, and erase cycles. In real
terms, a single endurance cycle is composed of four
independent, sequential events, as follows:
1. Initial page erase sequence
2. Read/verify sequence
3. Program sequence
4. Second read/verify sequence
ADD Pin
RETENTION (Years)
200
150
100
50
110
0
0
No Connect
1
0
VCC
0
1
Figure 16 and Figure 17 show timing diagrams for general
read and write operations using the SMBus. The SMBus
specification defines specific conditions for different types
of read and write operations, which are discussed later in this
section. The general SMBus protocol* operates as follows:
1. The master initiates data transfer by establishing a
start condition, defined as a high-to-low transition
on the serial data line (SDA) while the serial clock
line SCL remains high. This indicates that a data
stream follows. All slave peripherals connected to
the serial bus respond to the start condition and
shift in the next 8 bits, consisting of a 7-bit slave
address (MSB first) and an R/W bit, which
determine the direction of the data transfer, that is,
whether data is written to or read from the slave
device (0 = write, 1 = read).
The peripheral whose address corresponds to the
trans-mitted address responds by pulling the data
line low during the low period before the ninth
clock pulse, known as the acknowledge bit, and
holding it low during the high period of this clock
pulse. All other devices on the bus remain idle
while the selected device waits for data to be read
from or written to it. If the R/W bit is 0, the master
writes to the slave device. If the R/W bit is 1, the
master reads from the slave device.
250
60
70
80
90
100
JUNCTION TEMPERATURE (5C)
GND
General SMBus Timing
300
50
A0
If ADD is left open-circuit, the default address is 0101110
(5Ch). ADD is sampled only at powerup on the first valid
SMBus transaction, so any changes made while the power
is on (and the address is locked) have no effect.
The facility to make hardwired changes to device
addresses allows the user to avoid conflicts with other
devices sharing the same serial bus, for example if more than
one ADM1026 is used in a system.
In reliability qualification, every byte is cycled from 00h
to FFh until a first fail is recorded, signifying the endurance
limit of the EEPROM memory.
Retention quantifies the ability of the memory to retain its
programmed data over time. The EEPROM in the ADM1026
has been qualified in accordance with the formal JEDEC
Retention Lifetime Specification (A117) at a specific junction
temperature (TJ = 55C) to guarantee a minimum of 10 years
retention time. As part of this qualification procedure, the
EEPROM memory is cycled to its specified endurance limit
described above before data retention is characterized. This
means that the EEPROM memory is guaranteed to retain its
data for its full specified retention lifetime every time the
EEPROM is reprogrammed. Note that retention lifetime
based on an activation energy of 0.6 V derates with TJ, as
shown in Figure 15.
0
40
A1
120
Figure 15. Typical EEPROM Memory Retention
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11
ADM1026
2. Data is sent over the serial bus in sequences of nine
clock pulses, 8 bits of data followed by an
acknowledge bit from the slave device. Data
transitions on the data line must occur during the
low period of the clock signal and remain stable
during the high period, because a low-to-high
transition when the clock is high may be interpreted
as a stop signal.
If the operation is a write operation, the first data
byte after the slave address is a command byte.
This tells the slave device what to expect next. It
may be an instruction telling the slave device to
expect a block write, or it may simply be a register
address that tells the slave where subsequent data is
to be written.
Because data can flow in only one direction as
defined by the R/W bit, it is not possible to send a
command to a slave device during a read operation.
Before doing a read operation, it may first be
necessary to do a write operation to tell the slave
what type of read operation to expect and/or the
address from which data is to be read.
3. When all data bytes have been read or written, stop
conditions are established. In write mode, the master
pulls the data line high during the 10th clock pulse
to assert a stop condition. In read mode, the master
device releases the SDA line during the low period
before the ninth clock pulse, but the slave device
does not pull it low (called No Acknowledge). The
master takes the data line low during the low period
before the 10th clock pulse, then high during the
10th clock pulse to assert a stop condition.
*If it is required to perform several read or write operations in
succession, the master can send a repeat start condition instead
of a stop condition to begin a new operation.
1
9
1
9
SCL
0
SDA
1
0
1
1
A1
A0
D6
D7
R/W
START BY
MASTER
D4
D5
D2
D3
D1
D0
ACK. BY
SLAVE
ACK. BY
SLAVE
FRAME 1
SLAVE ADDRESS
FRAME 2
COMMAND CODE
1
9
9
1
SCL
(CONTINUED)
SDA
(CONTINUED)
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
ACK. BY
SLAVE
ACK. BY
SLAVE
FRAME 3
DATA BYTE
STOP BY
MASTER
FRAME N
DATA BYTE
Figure 16. General SMBus Write Timing Diagram
1
9
1
9
SCL
0
SDA
1
0
1
1
A1
A0
D6
D7
R/W
START BY
MASTER
D4
D5
D2
D3
D1
D0
ACK. BY
SLAVE
ACK. BY
MASTER
FRAME 1
SLAVE ADDRESS
FRAME 2
DATA BYTE
1
9
9
1
SCL
(CONTINUED)
SDA
(CONTINUED)
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
ACK. BY
MASTER
Figure 17. General SMBus Read Timing Diagram
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D0
NO ACK.
FRAME N
DATA BYTE
FRAME 3
DATA BYTE
D1
STOP BY
MASTER
ADM1026
SMBus Protocols for RAM and EEPROM
S − START
W − WRITE
P − STOP
A − ACKNOWLEDGE
R −READ
A − NO ACKNOWLEDGE
The ADM1026 contains volatile registers (RAM) and
non-volatile EEPROM. RAM occupies Addresses 00h to
6Fh, while EEPROM occupies Addresses 8000h to 9FFFh.
Data can be written to and read from both RAM and
EEPROM as single data bytes and as block (sequential) read
or write operations of 32 data bytes, the maximum block size
allowed by the SMBus specification.
Data can only be written to unprogrammed EEPROM
locations. To write new data to a programmed location, it is
first necessary to erase it. EEPROM erasure cannot be done
at the byte level; the EEPROM is arranged as 128 pages of
64 bytes, and an entire page must be erased. Note that of
these 128 pages, only 124 pages are available to the user. The
last four pages are reserved for manufacturing purposes and
cannot be erased/rewritten.
The EEPROM has three RAM registers associated with it,
EEPROM Registers 1, 2, and 3 at Addresses 06h, 0Ch, and
13h. EEPROM Registers 1 and 2 are for factory use only.
EEPROM Register 3 sets up the EEPROM operating mode.
Setting Bit 0 of EEPROM Register 3 puts the EEPROM into
read mode. Setting Bit 1 puts it into programming mode.
Setting Bit 2 puts it into erase mode.
Only one of these bits must be set before the EEPROM
may be accessed. Setting no bits or more than one of them
causes the device to respond with No Acknowledge if an
EEPROM read, program, or erase operation is attempted.
It is important to distinguish between SMBus write
operations, such as sending an address or command, and
EEPROM programming operations. It is possible to write an
EEPROM address over the SMBus, whatever the state of
EEPROM Register 3. However, EEPROM Register 3 must
be correctly set before a subsequent EEPROM operation can
be performed. For example, when reading from the
EEPROM, Bit 0 of EEPROM Register 3 can be set, even
though SMBus write operations are required to set up the
EEPROM address for reading. Bit 3 of EEPROM Register 3
is used for EEPROM write protection. Setting this bit
prevents accidental programming or erasure of the
EEPROM. If an EEPROM write or erase operation is
attempted when this bit is set, the ADM1026 responds with
No Acknowledge. This bit is write-once and can only be
cleared by a power-on reset.
EEPROM Register 3 Bit 7 is used for clock extend.
Programming an EEPROM byte takes approximately
250 ms, which would limit the SMBus clock for repeated or
block write operations. Because EEPROM block read/write
access is slow, it is recommended that this clock extend bit
typically be set to 1. This allows the ADM1026 to pull SCL
low and extend the clock pulse when it cannot accept any
more data.
ADM1026 Write Operations
Send Byte
In this operation, the master device sends a single
command byte to a slave device, as follows:
1. The master device asserts a start condition on the
SDA.
2. The master sends the 7-bit slave address followed
by the write bit (low).
3. The addressed slave device asserts an ACK on the
SDA.
4. The master sends a command code.
5. The slave asserts ACK on the SDA.
6. The master asserts a stop condition on the SDA
and the transaction ends.
In the ADM1026, the send byte protocol is used to write
a register address to RAM for a subsequent single−byte read
from the same address or block read or write starting at that
address. This is illustrated in Figure 18.
1
2
3
SLAVE
S
W A
ADDRESS
4
5
6
RAM
ADDRESS A P
(00h TO 6Fh)
Figure 18. Setting a RAM Address for Subsequent Read
If it is required to read data from the RAM immediately
after setting up the address, the master can assert a repeat
start condition immediately after the final ACK and carry
out a single byte read, block read, or block write operation
without asserting an intermediate stop condition.
Write Byte/Word
In this operation, the master device sends a command byte
and one or two data bytes to the slave device as follows:
1. The master device asserts a start condition on the
SDA.
2. The master sends the 7-bit slave address followed
by the write bit (low).
3. The addressed slave device asserts an ACK on the
SDA.
4. The master sends a command code.
5. The slave asserts an ACK on the SDA.
6. The master sends a data byte.
7. The slave asserts an ACK on the SDA.
8. The master sends a data byte (or may assert stop
here.)
9. The slave asserts an ACK on the SDA.
10. The master asserts a stop condition on the SDA to
end the transaction.
ADM1026 SMBus Operations
The SMBus specifications define several protocols for
different types of read and write operations. The ones used
in the ADM1026 are discussed below. The following
abbreviations are used in the diagrams:
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ADM1026
byte is the actual data. Bit 1 of EEPROM Register 3 must be
set. This is illustrated in Figure 22.
In the ADM1026, the write byte/word protocol is used for
four purposes. The ADM1026 knows how to respond by the
value of the command byte and EEPROM Register 3.
The first purpose is to write a single byte of data to RAM.
In this case, the command byte is the RAM address from 00h
to 6Fh and the (only) data byte is the actual data. This is
illustrated in Figure 19.
1
S
2
3
SLAVE
W A
ADDRESS
4
5
6
1
3
5
6
7
8
If it is required to read data from the EEPROM
immediately after setting up the address, the master can
assert a repeat start condition immediately after the final
ACK and carry out a single-byte read or block read operation
without asserting an intermediate stop condition. In this
case, Bit 0 of EEPROM Register 3 should be set.
The third use is to erase a page of EEPROM memory.
EEPROM memory can be written to only if it is previously
erased. Before writing to one or more EEPROM memory
locations that are already programmed, the page or pages
containing those locations must first be erased. EEPROM
memory is erased by writing an EEPROM page address plus
an arbitrary byte of data with Bit 2 of EEPROM Register 3
set to 1.
Because the EEPROM consists of 128 pages of 64 bytes,
the EEPROM page address consists of the EEPROM
address high byte (from 80h to 9Fh) and the two MSBs of the
low byte. The lower six bits of the EEPROM address (low
byte only) specify addresses within a page and are ignored
during an erase operation.
S
3
SLAVE
W A
ADDRESS
4
5
6
7
7
8
9 10
A
Y
In this operation, the master device writes a block of data
to a slave device. The start address for a block write must
have been set previously. In the case of the ADM1026, this
is done by a Send Byte operation to set a RAM address or by
a write byte/word operation to set an EEPROM address.
1. The master device asserts a start condition on the
SDA.
2. The master sends the 7-bit slave address followed
by the write bit (low).
3. The addressed slave device asserts an ACK on the
SDA.
4. The master sends a command code that tells the
slave device to expect a block write. The
ADM1026 command code for a block write is A0h
(10100000).
5. The slave asserts an ACK on the SDA.
6. The master sends a data byte (20h) that tells the
slave device that 32 data bytes are being sent to it.
The master should always send 32 data bytes to
the ADM1026.
7. The slave asserts an ACK on the SDA.
8. The master sends 32 data bytes.
9. The slave asserts an ACK on the SDA after each
data byte.
10. The master sends a packet error checking (PEC)
byte.
11. The ADM1026 checks the PEC byte and issues an
ACK if correct. If incorrect (NACK), the master
resends the data bytes.
12. The master asserts a stop condition on the SDA to
end the transaction.
Figure 20. Setting an EEPROM Address
2
6
Block Write
EEPROM
EEPROM
ADDRESS
SLAVE
S
W A
A ADDRESS A P
HIGH BYTE
ADDRESS
LOW BYTE
(80h TO 9Fh)
(00h TO FFh)
1
5
Figure 22. Single-Byte Write to EEPROM
RAM
ADDRESS A DATA A P
(00h TO 6Fh)
4
4
7 8
The protocol is also used to set up a 2-byte EEPROM
address for a subsequent read or block read. In this case, the
command byte is the high byte of the EEPROM address
from 80h to 9Fh. The (only) data byte is the low byte of the
EEPROM address. This is illustrated in Figure 20.
2
3
EEPROM
EEPROM
ADDRESS
ADDRESS
SLAVE
A
S
W A
A DATA
HIGH BYTE
LOW BYTE
ADDRESS
(80h TO 9Fh)
(00h TO FFh)
Figure 19. Single Byte Write to RAM
1
2
8
S
9 10
EEPROM
EEPROM
ADDRESS
ADDRESS
ARBITRARY A Y
A
A
HIGH BYTE
LOW BYTE
DATA
(80h TO 9Fh)
(00h TO FFh)
COMMAND
SLAVE W A
DATA A PEC A
A0h BLOCK A BYTE A DATA 1 A DATA 2 A
ADDRESS
32
COUNT
WRITE
P
Figure 23. Block Write to EEPROM or RAM
When performing a block write to EEPROM, Bit 1 of
EEPROM Register 3 must be set. Unlike some EEPROM
devices that limit block writes to within a page boundary,
there is no limitation on the start address when performing
a block write to EEPROM, except:
 There must be at least 32 locations from the start
address to the highest EEPROM address (9FF) to avoid
writing to invalid addresses.
 If the addresses cross a page boundary, both pages must
be erased before programming.
Figure 21. EEPROM Page Erasure
Page erasure takes approximately 20 ms. If the EEPROM
is accessed before erasure is complete, the ADM1026
responds with No Acknowledge.
Last, this protocol is used to write a single byte of data to
EEPROM. In this case, the command byte is the high byte
of the EEPROM address from 80h to 9Fh. The first data byte
is the low byte of the EEPROM address, and the second data
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ADM1026
ADM1026 Read Operations
ADM1026 always returns 32 data bytes (20h), the
maximum allowed by the SMBus 1.1 specification.
10. The master asserts an ACK on the SDA.
11. The master receives 32 data bytes.
12. The master asserts an ACK on the SDA after each
data byte.
13. The ADM1026 issues a PEC byte to the master.
The master should check the PEC byte and issue
another block read if the PEC byte is incorrect.
14. A NACK is generated after the PEC byte to signal
the end of the read.
15. The master asserts a stop condition on the SDA to
end the transaction.
The ADM1026 uses the SMBus read protocols described
here.
Receive Byte
In this operation, the master device receives a single byte
from a slave device as follows:
1. The master device asserts a start condition on the
SDA.
2. The master sends the 7-bit slave address followed
by the read bit (high).
3. The addressed slave device asserts an ACK on the
SDA.
4. The master receives a data byte.
5. The master asserts a NO ACK on the SDA.
6. The master asserts a stop condition on the SDA to
end the transaction.
In the ADM1026, the receive byte protocol is used to read
a single byte of data from a RAM or EEPROM location
whose address has previously been set by a send byte or
write byte/word operation. Figure 24 shows this. When
reading from EEPROM, Bit 0 of EEPROM Register 3 must
be set.
1
S
2
3
4
SLAVE
R A DATA
ADDRESS
5
S
COMMAND
SLAVE
W A A1h BLOCK A
ADDRESS
READ
A
BYTE
COUNT
A DATA 1 A
DATA
32
SLAVE
R
ADDRESS
S
A
PEC
A
P
Figure 25. Block Read from EEPROM or RAM
When block reading from EEPROM, Bit 0 of EEPROM
Register 3 must be set.
Note that although the ADM1026 supports Packet Error
Checking (PEC), its use is optional. The PEC byte is
calculated using CRC-8. The Frame Check Sequence (FCS)
conforms to CRC-8 by the polynomial:
6
A P
Figure 24. Single-Byte Read from EEPROM or RAM
Block Read
C(x) + x 8 ) x 2 ) x ) 1
In this operation, the master device reads a block of data
from a slave device. The start address for a block read must
have been set previously. In the case of the ADM1026 this
is done by a send byte operation to set a RAM address, or by
a write byte/word operation to set an EEPROM address. The
block read operation consists of a send byte operation that
sends a block read command to the slave, immediately
followed by a repeated start and a read operation that reads
out multiple data bytes as follows:
1. The master device asserts a start condition on the
SDA.
2. The master sends the 7-bit slave address followed
by the write bit (low).
3. The addressed slave device asserts an ACK on the
SDA.
4. The master sends a command code that tells the
slave device to expect a block read. The
ADM1026 command code for a block read is A 1h
(10100001).
5. The slave asserts an ACK on the SDA.
6. The master asserts a repeat start condition on the
SDA.
7. The master sends the 7-bit slave address followed
by the read bit (high).
8. The slave asserts an ACK on the SDA.
9. The ADM1026 sends a byte count data byte that
tells the master how many data bytes to expect. The
(eq. 1)
Consult the SMBus 1.1 Specification for more information.
Measurement Inputs
The ADM1026 has 17 external analog measurement pins
that can be configured to perform various functions. It also
measures two supply voltages, 3.3 V MAIN and 3.3 V
STBY, and the internal chip temperature.
Pins 25 and 26 are dedicated to remote temperature
measurement, while Pins 27 and 28 can be configured as
analog inputs with a range of 0 V to 2.5 V, or as inputs for
a second remote temperature sensor.
Pins 29 to 33 are dedicated to measuring VBAT, +5.0 V,
−12 V, +12 V supplies, and the processor core voltage VCCP.
The remaining analog inputs, Pins 34 to 41, are
general-purpose analog inputs with a range of 0 V to 2.5 V
(Pins 34 and 35) or 0 V to 3.0 V (Pins 36 to 41).
A-to-D Converter (ADC)
These inputs are multiplexed into the on-chip, successive
approximation, analog-to-digital converter. The ADC has a
resolution of 8 bits. The basic input range is 0 V to 2.5 V,
which is the input range of AIN6 to AIN9, but five of the
inputs have built-in attenuators to allow measurement of
VBAT, +5.0 V, -12 V, +12 V, and the processor core voltage
VCCP, without any external components. To allow the
tolerance of these supply voltages, the ADC produces an
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15
ADM1026
averaged to reduce noise, so the total conversion time for each
input is 11.38 ms.
Measurements on the remote temperature (D1 and D2)
inputs take 2.13 ms. These are also measured 16 times and
are averaged, so the total conversion time for a remote
temperature input is 34.13 ms.
output of 3/4 full scale (decimal 192) for the nominal input
voltage, and so has adequate headroom to cope with over
voltages. Table 7 shows the input ranges of the analog inputs
and output codes of the ADC.
When the ADC is running, it samples and converts an
analog or local temperature input every 711 ms (typical value).
Each input is measured 16 times and the measurements are
Table 7. A-TO-D OUTPUT CODES VS. VIN
Input Voltage
A-to-D Output
+12 VIN
–12 VIN
+5.0 VIN
3.3 V MAIN
VBAT
VCCP
AIN (0–5)
AIN (6–9)
Decimal
Binary
< 0.0625
< −15.928
< 0.026
< 0.0172
NA
< 0.012
< 0.012
< 0.010
0
00000000
0.062−0.125
−15.928−15.855
0.026−0.052
0.017−0.034
NA
0.012−0.023
0.012−0.023
0.010−0.019
1
00000001
0.125−0.187
−15.855−15.783
0.052−0.078
0.034−0.052
NA
0.023−0.035
0.023−0.035
0.019−0.029
2
00000010
0.188−0.250
−15.783−15.711
0.078−0.104
0.052−0.069
NA
0.035−0.047
0.035−0.047
0.029−0.039
3
00000011
0.250−0.313
−15.711−15.639
0.104−0.130
0.069−0.086
NA
0.047−0.058
0.047−0.058
0.039−0.049
4
00000100
0.313−0.375
−15.639−15.566
0.130−0.156
0.086−0.103
NA
0.058−0.070
0.058−0.070
0.049−0.058
5
00000101
0.375−0.438
−15.566−15.494
0.156−0.182
0.103−0.120
NA
0.070−0.082
0.070−0.082
0.058−0.068
6
00000110
0.438−0.500
−15.494−15.422
0.182−0.208
0.120−0.138
NA
0.082−0.094
0.082−0.094
0.068−0.078
7
00000111
0.500−0.563
−15.422−15.349
0.208−0.234
0.138−0.155
NA
0.094−0.105
0.094−0.105
0.078−0.087
8
00001000
1.667−1.693
1.110−1.127
NA
0.750−0.780
0.750−0.780
0.625−0.635
64
(1⁄4 scale)
01000000
3.333−3.359
2.000−2.016
2.000−2.016
1.500−1.512
1.500−1.512
1.250−1.260
128
(1⁄2 scale)
10000000
5−5.026
3.330−3.347
3.000−3.016
2.250−2.262
2.250−2.262
1.875−1.885
192
(3⁄4 scale)
11000000
−
−
−
4.000−4.063
−11.375−11.303
−
−
−
8.000−8.063
−6.750−6.678
−
−
−
12.000−12.063
−2.125−2.053
−
−
−
15.313−15.375
1.705−1.777
6.38−6.406
4.249−4.267
3.828−3.844
2.871−2.883
2.871−2.883
2.392−2.402
245
11110101
15.375−15.437
1.777−1.850
6.406−6.432
4.267−4.284
3.844−3.860
2.883−2.895
2.883−2.895
2.402−2.412
246
11110110
15.437−15.500
1.850−1.922
6.432−6.458
4.284−4.301
3.860−3.875
2.895−2.906
2.895−2.906
2.412−2.422
247
11110111
15.500−15.563
1.922−1.994
6.458−6.484
4.301−4.319
3.875−3.890
2.906−2.918
2.906−2.918
2.422−2.431
248
11111000
15.562−15.625
1.994−2.066
6.484−6.51
4.319−4.336
3.890−3.906
2.918−2.930
2.918−2.930
2.431−2.441
249
11111001
15.625−15.688
2.066−2.139
6.51−6.536
4.336−4.353
3.906−3.921
2.930−2.941
2.930−2.941
2.441−2.451
250
11111010
15.688−15.750
2.139−2.211
6.536−6.563
4.353−4.371
3.921−3.937
2.941−2.953
2.941−2.953
2.451−2.460
251
11111011
15.750−15.812
2.211−2.283
6.563−6.589
4.371−4.388
3.937−3.953
2.953−2.965
2.953−2.965
2.460−2.470
252
11111100
15.812−15.875
2.283−2.355
6.589−6.615
4.388−4.405
3.953−3.969
2.965−2.977
2.965−2.977
2.470−2.480
253
11111101
15.875−15.938
2.355−2.428
6.615−6.641
4.405−4.423
3.969−3.984
2.977−2.988
2.977−2.988
2.480−2.490
254
11111110
>15.938
>2.428
>6.634
>4.423
>3.984
>2.988
>2.988
>2.490
255
11111111
1. * VBAT is not accurate for voltages under 1.5 V (see Figure 14).
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ADM1026
Voltage Measurement Inputs
However, when scaling AIN0 to AIN5, it should be noted
that these inputs already have an on-chip attenuator, because
their primary function is to monitor SCSI termination
voltages. This attenuator loads any external attenuator. The
input resistance of the on-chip attenuator can be between
100 kW and 200 kW. For this tolerance not to affect the
accuracy, the output resistance of the external attenuator
should be very much lower than this, that is, 1 kW in order
to add not more than 1% to the total unadjusted error (TUE).
Alternatively, the input can be buffered using an op amp.
The internal structure for all the analog inputs is shown in
Figure 26. Each input circuit consists of an input protection
diode, an attenuator, plus a capacitor to form a first-order
low-pass filter that gives each voltage measurement input
immunity to high frequency noise. The −12 V input also has
a resistor connected to the on-chip reference to offset the
negative voltage range so that it is always positive and can
be handled by the ADC. This allows most popular power
supply voltages to be monitored directly by the ADM1026
without requiring any additional resistor scaling.
R1 +
R2
21.9k
AIN0 – A IN5
(0V – 3V)
109.4k
4.6pF
R1 +
R2
52.5k
AIN6 – A IN9
(0V – 2.5V)
113.5k
9.3pF
21k
3.0
ǒVfs * 2.5Ǔ
2.5
ǒfor
A IN0 through A IN5Ǔ
(eq. 2)
ǒfor
A IN6 through A IN9Ǔ
(eq. 3)
Negative and bipolar input ranges can be accommodated
by using a positive reference voltage to offset the input
voltage range so that it is always positive. To monitor a
negative input voltage, an attenuator can be used as shown
in Figure 28.
4.6pF
+12V
ǒVfs * 3.0Ǔ
VREF
R2
17.5k
MUX
114.3k
–12V
VIN
R1
AIN(0–9)
9.3pF
83.5k
+5V
50k
Figure 28. Scaling and Offsetting AIN0 − AIN9
for Negative Inputs
4.6pF
This offsets the negative voltage so that the ADC always
sees a positive voltage. R1 and R2 are chosen so that the
ADC input voltage is zero when the negative input voltage
is at its maximum (most negative) value, that is:
49.5k
VBAT
82.7k
4.5pF
* SEE TEXT
R1 +
R2
21.9k
+VCCP
109.4k
18.5pF
Setting Other Input Ranges
AIN0 to AIN9 can easily be scaled to voltages other than
2.5 V or 3.0 V. If the input voltage range is zero to some
positive voltage, all that is required is an input attenuator, as
shown in Figure 27.
R1
Vf *
s
V OS
(eq. 4)
This is a simple and low cost solution, but note the
following:
 Because the input signal is offset but not inverted, the
input range is transposed. An increase in the magnitude
of the negative voltage (going more negative) causes the
input voltage to fall and give a lower output code from
the ADC. Conversely, a decrease in the magnitude of the
negative voltage causes the ADC code to increase. The
maximum negative voltage corresponds to zero output
from the ADC. This means that the upper and lower
limits are transposed.
 For the ADC output to be full scale when the negative
voltage is zero, VOS must be greater than the full−scale
voltage of the ADC, because VOS is attenuated by R1 and
R2. If VOS is equal to or less than the full−scale voltage
of the ADC, the input range is bipolar but not necessarily
symmetrical.
Figure 26. Voltage Measurement Inputs
VIN
Ť Ť
AIN(0–9)
R2
Figure 27. Scaling AIN0 − AIN9
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ADM1026
For example, when VBAT = 3.0 V,
This is a problem only if the ADC output must be full scale
when the negative voltage is zero.
Symmetrical bipolar input ranges can be accommodated
easily by making VOS equal to the full-scale voltage of the
analog input, and by adding a third resistor to set the positive
full scale.
I+
In addition to minimizing battery current drain, the VBAT
measurement circuitry was specifically designed with
battery protection in mind. Internal circuitry prevents the
battery from being back-biased by the ADM1026 supply or
through any other path under normal operating conditions.
In the unlikely event of a catastrophic ADM1026 failure, the
ADM1026 includes a second level of battery protection
including a series 3 kW resistor to limit current to the battery,
as recommended by UL. Thus, it is not necessary to add a
series resistor between the battery and the VBAT input; the
battery can be connected directly to the VBAT input to
improve voltage measurement accuracy.
AIN(0–9)
R3
Figure 29. Scaling and Offsetting AIN0 − AIN9
for Bipolar Inputs
Ť
V *
R1 + fs
V OS
R2
Ť
(eq. 5)
Note that R3 has no effect as the input voltage at the device
pin is zero when VIN = negative full scale.
R1 +
R3
R1 +
R3
ǒVfs * 3.0Ǔ
3.0
ǒVfs * 2.5Ǔ
2.5
ǒfor
A IN0 through A IN5Ǔ
VBAT
49.5k
A IN6 through A IN9Ǔ
Reference Output (VREF)
The ADM1026 offers an on-chip reference voltage
(Pin 24) that can be used to provide a 1.82 V or 2.5 V
reference voltage output. This output is buffered and
specified to sink or source a load current of 2 mA. The
reference voltage outputs 1.82 V if Bit 2 of Configuration
Register 3 (Address 07h) is 0; it outputs 2.5 V when this bit
is set to 1. This voltage reference output can be used to
provide a stable reference voltage to external circuitry such
as LDOs. The load regulation of the VREF output is typically
0.15% for a sink current of 2 mA and 0.15% for 2 mA source
current. There may be some ripple present on the VREF
output that requires filtering (4 m VMAX). Figure 31 shows
the recommended circuitry for the VREF output for loads less
than 2 mA. For loads in excess of 2 mA, external circuitry,
such as that shown in Figure 32, can be used to buffer the
VREF output.
The VBAT input allows the condition of a CMOS backup
battery to be monitored. This is typically a lithium coin cell
such as a CR2032. The VBAT input is accurate only for
voltages greater than 1.5 V (see Figure 14). Typically, the
battery in a system is required to keep some device powered
on when the system is in a powered-off state. The VBAT
measurement input is specially designed to minimize battery
drain. To reduce current drain from the battery, the lower
resistor of the VBAT attenuator is not connected, except
whenever a VBAT measurement is being made. The total
current drain on the VBAT pin is 80 nA typical (for a
maximum VBAT voltage = 4.0 V), so a CR2032 CMOS
battery functions in a system in excess of the expected 10
years. Note that when a VBAT measurement is not being
made, the current drain is reduced to 6 nA typical. Under
normal voltage measurement operating conditions, all
measurements are made in a round-robin format, and each
reading is actually the result of 16 digitally averaged
measurements. However, averaging is not carried out on the
VBAT measurement to reduce measurement time and
therefore reduce the current drain from the battery.
The VBAT current drain when a measurement is being
made is calculated by:
T PULSE
T PERIOD
ADC
Figure 30. Equivalent VBAT Input Protection Circuit
Battery Measurement Input (VBAT)
V BAT
100 kW
3k
82.7k
(eq. 7)
Also, note that R2 has no effect as the input voltage at the
device pin is equal to VOS when VIN = positive full scale.
I+
DIGITAL
CONTROL
3k
(eq. 6)
4.5pF
ǒfor
(eq. 9)
VBAT Input Battery Protection
R2
R1
711 ms
+ 78 nA
273 ms
where TPULSE = VBAT measurement time (711 ms typical),
TPERIOD = time to measure all analog inputs (273 ms
typical), and VBAT input battery protection.
+VOS
VIN
3.0 V
100 kW
ADM1026
24
VREF
10k
VREF
0.1F
(eq. 8)
Figure 31. VREF Interface Circuit for VREF Loads < 2 mA
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ADM1026
by clearing Bit 3 of Configuration Register 1 (Address 00h)
to 0. If this bit is 1, then Pins 27 and 28 are AIN8 and AIN9.
The forward voltage of a diode or diode-connected
transistor, operated at a constant current, exhibits a negative
temperature coefficient of about −2 mV/C. Unfortunately,
the absolute value of Vbe varies from device to device, and
individual calibration is required to null this out, so the
technique is unsuitable for mass production.
The technique used in the ADM1026 is to measure the
change in Vbe when the device is operated at two different
currents, given by:
If the VREF output is not being used, it should be left
unconnected. Do not connect VREF to GND using a
capacitor. The internal output buffer on the voltage reference
is capacitively loaded, which can cause the voltage reference
to oscillate. This affects temperature readings reported back
by the ADM1026. The recommended interface circuit for
the VREF output is shown in Figure 32.
+12V
ADM1026
VREF
24
10k
DV be + K q T
NDT3055
50
0.1F
10F
Figure 32. VREF Interface Circuit for VREF Loads > 2 mA
Temperature Measurement System
Local Temperature Measurement
The ADM1026 contains an on-chip band gap temperature
sensor whose output is digitized by the on-chip ADC. The
temperature data is stored in the local temperature value
register (Address 1Fh). As both positive and negative
temperatures can be measured, the temperature data is stored
in twos complement format, as shown in Table 8.
Theoretically, the temperature sensor and ADC can measure
temperatures from −128C to +127C with a resolution of
1C. Temperatures below TMIN and above TMAX are outside
the operating temperature range of the device; however, so
local temperature measurements outside this range are not
possible. Temperature measurement from −128C to
+127C is possible using a remote sensor.
Remote Temperature Measurement
The ADM1026 can measure the temperature of two
remote diode sensors, or diode-connected transistors,
connected to Pins 25 and 26, or 27 and 28.
Pins 25 and 26 are a dedicated temperature input channel.
Pins 27 and 28 can be configured to measure a diode sensor
VDD
I
NxI
IBIAS
D+
REMOTE
SENSING
TRANSISTOR
VOUT+
TO ADC
C1*
D–
BIAS
DIODE
(eq. 10)
where K is Boltzmann’s constant, q is the charge on the
carrier, T is the absolute temperature in Kelvins, and N is the
ratio of the two currents.
Figure 33 shows the input signal conditioning used to
measure the output of a remote temperature sensor. This
figure shows the external sensor as a substrate transistor
provided for temperature monitoring on some
microprocessors, but it could equally well be a discrete
transistor such as a 2N3904.
If a discrete transistor is used, the collector is not grounded
and should be linked to the base. If a PNP transistor is used,
the base is connected to the D− input and the emitter to the
D+ input. If an NPN transistor is used, the emitter is
connected to the D− input and the base to the D+ input.
To prevent ground noise from interfering with the
measurement, the more negative terminal of the sensor is not
referenced to ground but is biased above ground by an
internal diode at the D− input.
To measure DVbe, the sensor is switched between
operating currents of I and N  I. The resulting waveform is
passed through a 65 kHz low−pass filter to remove noise,
and to a chopper-stabilized amplifier that performs the
functions of amplification and rectification of the waveform
to produce a DC voltage proportional to DVbe. This voltage
is measured by the ADC to give a temperature output in
8-bit, twos complement format. To further reduce the effects
of noise, digital filtering is performed by averaging the
results of 16 measurement cycles. A remote temperature
measurement takes nominally 2.14 ms.
VREF
0.1F
log n (N)
LOW−PASS FILTER
fC = 65kHz
VOUT–
* CAPACITOR C1 IS OPTIONAL. IT IS ONLY NECESSARY IN NOISY ENVIRONMENTS.
C1 = 2.2nF TYPICAL, 3nF MAX.
Figure 33. Signal Conditioning for Remote Diode Temperature Sensors
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ADM1026
The results of external temperature measurements are
stored in 8-bit, twos complement format, as illustrated in
Table 8.
Table 8. TEMPERATURE DATA FORMAT
Temperature
Digital Output
Hex
−128C
1000 0000
80
−125C
1000 0011
83
−100C
1001 1100
9C
−75C
1011 0101
B5
−50C
1100 1110
CE
−25C
1110 0111
E7
−10C
1111 0110
F6
0C
0000 0000
00
10C
0000 1010
0A
25C
0001 1001
19
50C
0011 0010
32
75C
0100 1011
4B
100C
0110 0100
64
125C
0111 1101
7D
127C
0111 1111
7F



Because the measurement technique uses switched
current sources, excessive cable and/or filter capacitance
can affect the measurement. When using long cables, the
filter capacitor may be reduced or removed. Cable resistance
can also introduce errors. A 1 W series resistance introduces
about 0.5C error.
Limit Values
Limit values for analog measurements are stored in the
appropriate limit registers. In the case of voltage
measurements, high and low limits can be stored so that an
interrupt request is generated if the measured value goes
above or below acceptable values. In the case of
temperature, a hot temperature or high limit can be
programmed, and a hot temperature hysteresis or low limit
can be programmed, which is usually some degrees lower.
This can be useful because it allows the system to be shut
down when the hot limit is exceeded, and restarted
automatically when it has cooled down to a safe
temperature.
Layout Considerations
Digital boards can be electrically noisy environments.
Take these precautions to protect the analog inputs from
noise, particularly when measuring the very small voltages
from a remote diode sensor.
 Place the ADM1026 as close as possible to the remote
sensing diode. Provided that the worst noise sources
such as clock generators, data/address buses, and CRTs
are avoided, this distance can be 4 to 8 inches.
 Route the D+ and D− tracks close together, in parallel,
with grounded guard tracks on each side. Provide a
ground plane under the tracks if possible.
 Use wide tracks to minimize inductance and reduce noise
pickup. A 10 mil track minimum width and spacing is
recommended.
GND
Analog Monitoring Cycle Time
The analog monitoring cycle begins when a 1 is written to
the start bit (Bit 0), and a 0 to the INT_Clear bit (Bit 2) of the
configuration register. INT_Enable (Bit 1) should be set to
1 to enable the INT output. The ADC measures each analog
input in turn, starting with Remote Temperature Channel 1
and ending with local temperature. As each measurement is
completed, the result is automatically stored in the
appropriate value register. This round-robin monitoring
cycle continues until it is disabled by writing a 0 to Bit 0 of
the configuration register. Because the ADC is typically left
to free-run in this way, the most recently measured value of
any input can be read out at any time.
For applications where the monitoring cycle time is
important, it can easily be calculated.
The total number of channels measured is:
 Five Dedicated Supply Voltage Inputs
 Ten General-purpose Analog Inputs
 3.3 V MAIN
 3.3 V STBY
 Local Temperature
 Two Remote Temperature
10MIL
10MIL
D+
10MIL
10MIL
D–
10MIL
10MIL
GND
10MIL
Figure 34. Arrangement of Signal Tracks
 Try to minimize the number of copper/solder joints,

thermocouple voltages are about 3 mV/C of temperature
difference. Unless there are two thermocouples with a
big temperature differential between them, thermocouple
voltages should be much less than 200 mV.
Place a 0.1 mF bypass capacitor close to the ADM1026.
If the distance to the remote sensor is more than eight
inches, the use of twisted-pair cable is recommended.
This works from about 6 to 12 feet.
For very long distances (up to 100 feet), use shielded
twisted pair such as Belden #8451 microphone cable.
Connect the twisted pair to D+ and D− and the shield to
GND close to the ADM1026. Leave the remote end of
the shield unconnected to avoid ground loops.
which can cause thermocouple effects. Where copper/
solder joints are used, make sure that they are in both
the D+ and D− paths and are at the same temperature.
Thermocouple effects should not be a major problem
because 1C corresponds to about 240 mV, and
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ADM1026
Pins 28 and 27 are measured both as analog inputs
AIN8/AIN9 and as remote temperature input D2+/D2−,
irrespective of which configuration is selected for these pins.
If Pins 28 and 27 are configured as AIN8/AIN9, the
measurements for these channels are stored in Registers 27h
and 29h, and the invalid temperature measurement is
discarded. On the other hand, if Pins 28 and 27 are configured
as D2+/D2−, the temperature measurement is stored in
Register 29h, and there is no valid result in Register 27h.
As mentioned previously, the ADC performs a conversion
every 711 ms on the analog and local temperature inputs and
every 2.13 ms on the remote temperature inputs. Each input
is measured 16 times and averaged to reduce noise.
The total monitoring cycle time for voltage and
temperature inputs is therefore nominally:
(18
16
0.711) ) (2
16
 To amplify the 2.5 V range of the analog output up to



2.13) + 273 ms (eq. 11)
The ADC uses the internal 22.5 kHz clock, which has a
tolerance of 6%, so the worst-case monitoring cycle time
is 290 ms. The fan speed measurement uses a completely
separate monitoring loop, as described later.

Input Safety

Scaling of the analog inputs is performed on-chip, so
external attenuators are typically not required. However,
because the power supply voltages appear directly at the
pins, it is advisable to add small external resistors (that is,
500 W) in series with the supply traces to the chip to prevent
damaging the traces or power supplies should an accidental
short such as a probe connect two power supplies together.
Because the resistors form part of the input attenuators,
they affect the accuracy of the analog measurement if their
value is too high. The worst such accident would be
connecting −12 V to +12 V where there is a total of 24 V
difference. With the series resistors, this would draw a
maximum current of approximately 24 mA.
12 V, the gain of these circuits needs to be about 4.8.
Take care when choosing the op amp to ensure that its
input common-mode range and output voltage swing
are suitable.
The op amp may be powered from the +12 V rail alone
or from 12 V. If it is powered from +12 V, the input
common-mode range should include ground to
accommodate the minimum output voltage of the DAC,
and the output voltage should swing below 0.6 V to
ensure that the transistor can be turned fully off.
If the op amp is powered from −12 V, precautions such
as a clamp diode to ground may be needed to prevent
the base-emitter junction of the output transistor being
reverse-biased in the unlikely event that the output of
the op amp should swing negative for any reason.
In all these circuits, the output transistor must have an
ICMAX greater than the maximum fan current, and be
capable of dissipating power due to the voltage dropped
across it when the fan is not operating at full speed.
If the fan motor produces a large back EMF when
switched off, it may be necessary to add clamp diodes
to protect the output transistors in the event that the
output goes from full scale to zero very quickly.
12 V
1/4
LM324
DAC
Q1
2N2219A
R1
10k
Analog Output
The ADM1026 has a single analog output from an
unsigned 8-bit DAC that produces 0 V to 2.5 V
(independent of the reference voltage setting). The input
data for this DAC is contained in the DAC control register
(Address 04h). The DAC control register defaults to FFh
during a power-on reset, which produces maximum fan
speed. The analog output may be amplified and buffered
with external circuitry such as an op amp and a transistor to
provide fan speed control. During automatic fan speed
control, described later, the four MSBs of this register set the
minimum fan speed.
Suitable fan drive circuits are shown in Figure 35 through
Figure 39. When using any of these circuits, note the
following:
 All of these circuits provide an output range from 0 V
to almost +12 V, apart from Figure 35, which loses the
base-emitter voltage drop of Q1 due to the
emitter-follower configuration.
Figure 35. Fan Drive Circuit with Op Amp and
Emitter-follower
12 V
1/4
LM324
R4
1kW
DAC
R3
1kW
Q1
BD136
2SA968
R2
39kW
R1
10k
Figure 36. Fan Drive Circuit with Op Amp and PNP
Transistor
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ADM1026
described below, the four MSBs of this register set the
minimum fan speed.
The open drain PWM output must be amplified and
buffered to drive the fans. The PWM output is intended to
be used with an NMOS driver, but may be inverted by setting
Bit 1 of Test Register 1 (Address 14h) if using PMOS
drivers. Figure 40 shows how a fan may be driven under
PWM control using an N-channel MOSFET.
12 V
1/4
LM324
R3
100kW
DAC
Q1
IRF9620
R2
39kW
+V
R1
10k
5.0 V OR 12 V
FAN
3.3 V
10k TYP
Figure 37. Fan Drive Circuit with Op Amp and
P-channel MOSFET
PWM
Q1
NDT3055L
12 V
R2
100kW
R2
100kW
Figure 40. PWM Fan Drive Circuit Using an
N-channel MOSFET
Q3
IRF9620
Automatic Fan Speed Control
DAC
The ADM1026 offers a simple method of controlling fan
speed according to temperature without intervention from
the host processor. Monitoring must be enabled by setting
Bit 0 of Configuration Register 1 (Address 00h), to enable
automatic fan speed control. Automatic fan speed control
can be applied to the DAC output, the PWM output, or both,
by setting Bit 5 and/or Bit 6 of Configuration Register 1.
The TMIN registers (Addresses 10h to 12h) contain
minimum temperature values for the three temperature
channels (on-chip sensor and two remote diodes). This is the
temperature at which a fan starts to operate when the
temperature sensed by the controlling sensor exceeds TMIN.
TMIN can be the same or different for all three channels.
TMIN is set by writing a twos complement temperature value
to the TMIN registers. If any sensor channel is not required
for automatic fan speed control, TMIN for that channel
should be set to 127C (01111111).
In automatic fan speed control mode, (as shown Figure 41
and Figure 42) the four MSBs of the DAC control register
(Address 04h) and PWM control register (Address 05h) set
the minimum values for the DAC and PWM outputs. Note
that, if both DAC control and PWM control are enabled
(Bits 5 and 6 of Configuration Register 1 = 1), the four MSBs
of the DAC control register (Address 04h) define the
minimum fan speed values for both the DAC and PWM
outputs. The value in the PWM control register (Address 05h)
has no effect.
Minimum DAC Code DACMIN = 16  D
R3
39k
Q1/Q2
MBT3904
DUAL
R4
10k
Figure 38. Discrete Fan Drive Circuit with P-channel
MOSFET, Single Supply
+12 V
R2
100kW
Q3
IRF9620
DAC
Q1/Q2
MBT3904
DUAL
R3
39k
R4
10k
R1
4.7k
–12 V
Figure 39. Discrete Fan Drive Circuit with P-channel
MOSFET, Dual Supply
PWM Output
DAC Output Voltage + 2.5
Fan speed may also be controlled using pulse width
modulation (PWM). The PWM output (Pin 18) produces a
pulsed output with a frequency of approximately 75 Hz and
a duty cycle defined by the contents of the PWM control
register (Address 05h). During automatic fan speed control,
Code
256
(eq. 12)
Minimum PWM Duty Cycle PWMMIN = 6.67  D
where D is the decimal equivalent of Bits 7 to 4 of the
register.
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ADM1026
When the temperature measured by any of the sensors
exceeds the corresponding TMIN, the fan is spun up for
2 seconds with the fan drive set to maximum (full scale from
the DAC or 100% PWM duty cycle). The fan speed is then
set to the minimum as previously defined. As the
temperature increases, the fan drive increases until the
temperature reaches TMIN + 20C.
The fan drive at any temperature up to 20C above TMIN
is given by:
PWM + PWM MIN ) ǒ100 * PWM MINǓ
SPIN UP FOR 2 SECONDS
255
240
DAC
OUTPUT
MIN
T ACTUAL * T MIN
20
(eq. 13)
TMIN - 45C
or
TMIN
TMIN + 205C
TEMPERATURE
DAC + DAC MIN ) ǒ240 * DAC MINǓ
Figure 42. Automatic DAC Fan Control Transfer
Function
T ACTUAL * T MIN
20
(eq. 14)
Fan Inputs
Pins 3 to 6 and 9 to 12 may be configured as fan speed
measuring inputs by clearing the corresponding bit(s) of
Configuration Register 2 (Address 01h), or as
general-purpose logic inputs/outputs by setting bits in this
register. The power-on default value for this register is 00h,
which means all the inputs are set for fan speed
measurement.
Signal conditioning in the ADM1026 accommodates the
slow rise and fall times typical of fan tachometer outputs.
The fan tach inputs have internal 10 kW pullup resistors to
3.3 V STBY. In the event that these inputs are supplied from
fan outputs that exceed the supply, either resistive
attenuation of the fan signal or diode clamping must be
included to keep inputs within an acceptable range.
Figure 43 through Figure 47 show circuits for common fan
tach outputs.
If the fan tach output is open-drain or has a resistive pullup
to VCC, then it can be connected directly to the fan input, as
shown in Figure 44.
For simplicity of the automatic fan speed algorithm, the
DAC code increases linearly up to 240, not its full scale of
255. However, when the temperature exceeds TMIN +20C,
the DAC output jumps to full scale. To ensure that the
maximum cooling capacity is always available, the fan drive
is always set by the sensor channel demanding the highest
fan speed.
If the temperature falls, the fan does not turn off until the
temperature measured by all three temperature sensors has
fallen to their corresponding TMIN − 4C. This prevents the
fan from cycling on and off continuously when the
temperature is close to TMIN.
Whenever a fan starts or stops during automatic fan speed
control, a one-off interrupt is generated at the INT output.
This is described in more detail in the section on the
ADM1026 Interrupt Structure.
SPIN UP FOR 2 SECONDS
100%
12 V
PWM
OUTPUT
PULLUP
4.7k
TYP
VCC
FAN(0–7)
FAN SPEED
COUNTER
MIN
Figure 43. Fan with Tach Pullup to +VCC
TMIN ć 45C
TMIN
If the fan output has a resistive pullup to +12 V (or other
voltage greater than 3.3 V STBY), the fan output can be
clamped with a Zener diode, as shown in Figure 46. The
Zener voltage should be chosen so that it is greater than VIH
but less than 3.3 V STBY, allowing for the voltage tolerance
of the Zener.
TMIN + 205C
TEMPERATURE
Figure 41. Automatic PWM Fan Control Transfer
Function
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ADM1026
12 V
22.5kHz
CLOCK
VCC
CONFIGURATION
REG. 1 BIT 0
PULLUP
4.7k
TYP
FAN(0–7)
FAN SPEED
COUNTER
1
2
3
4
FAN0
INPUT
1
* CHOOSE ZD1 VOLTAGE APPROXIMATELY 0.8 x VCC
Figure 44. Fan with Tach Pullup to Voltage > VCC
(e.g. 12 V), Clamped with Zener Diode
START OF
MONITORING
CYCLE
If the fan has a strong pullup (less than 1 kW) to +12 V, or
a totem pole output, a series resistor can be added to limit the
Zener current, as shown in Figure 45. Alternatively, a
resistive attenuator may be used, as shown in Figure 47.
R1 and R2 should be chosen such that:
2.0 V t V PULLUP
R2
ǒR PULLUP ) R1 ) R2Ǔ
12 V
FAN(0–7)
t 3.3 V STBY
(eq. 15)
FAN SPEED
COUNTER
* CHOOSE ZD1 VOLTAGE APPROXIMATELY 0.8 x VCC
VCC
<1 k
R1*
FAN(0–7)
TACH
OUTPUT
FAN1
MEASUREMENT
PERIOD
The monitoring cycle begins when a 1 is written to the
monitor bit (Bit 0 of Configuration Register 1). The
INT_Enable (Bit 1) should be set to 1 to enable the INT
output.
The fan speed counter starts counting as soon as the fan
channel has been switched to. If the fan tach count reaches
0xFF, the fan has failed or is not connected. If a fan is
connected and running, the counter is reset on the second
tach rising edge, and oscillator pulses are actually counted
from the second rising tach edge to the fourth rising edge.
The measurement then switches to the next fan channel.
Here again, the counter begins counting and is reset on the
second tach rising edge, and oscillator pulses are counted
from the second rising edge to the fourth rising edge. This
is repeated for the other six fan channels.
Note that fan speed measurement does not occur until
1.8 seconds after the monitor bit has been set. This is to
allow the fans adequate time to spin up. Otherwise, the
ADM1026 could generate false fan failure interrupts.
During the 1.8 second fan spin-up time, all fan tach registers
read 0x00.
To accommodate fans of different speed and/or different
numbers of output pulses per revolution, a prescaler
(divisor) of 1, 2, 4, or 8 may be added before the counter.
Divisor values for Fans 0 to 3 are contained in the Fan 0–3
divisor register (Address 02h) and those for Fans 4 to 7 in the
Fan 4–7 divisor register (Address 03h). The default value
is 2, which gives a count of 153 for a fan running at
4400 RPM producing two output pulses per revolution. The
count is calculated by the equation:
Figure 45. Fan with Strong Tach Pullup to >VCC or
Totem Pole Output, Attenuated with R1/R2
12 V
4
3
Figure 47. Fan Speed Measurement
VCC
PULLUP TYP
<1 k
FAN0
MEASUREMENT
PERIOD
2
FAN SPEED
COUNTER
* SEE TEXT
Figure 46. Fan with Strong Tach Pullup to > VCC or
Totem Pole Output, Clamped with Zener and Resistor
Fan Speed Measurement
The fan counter does not count the fan tach output pulses
directly because the fan speed may be less than 1000 RPM
and it would take several seconds to accumulate a
reasonably large and accurate count. Instead, the period of
the fan revolution is measured by gating an on-chip
22.5 kHz oscillator into the input of an 8-bit counter for two
periods of the fan tach output, as shown in Figure 47, so the
accumulated count is actually proportional to the fan tach
period and inversely proportional to the fan speed.
3
60
Count + 22.5 10
RPM Divisor
(eq. 16)
For constant-speed fans, fan failure is typically
considered to have occurred when the speed drops below
70% of nominal, corresponding to a count of 219. Full scale
(255) is reached if the fan speed fell to 60% of its nominal
value. For temperature-controlled, variable-speed fans, the
situation is different.
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ADM1026
initialization or before the fourth tach pulse during
measurement, the measurement is terminated. This also
occurs if an input is configured as GPIO instead of fan. Any
channels connected in this manner time out after 255 clock
pulses.
The worst-case measurement time for a fan−configured
channel occurs when the counter reaches 254 from start to
the second tach pulse and reaches 255 after the second tach
pulse. Taking into account the tolerance of the oscillator
frequency, the worst-case measurement time is:
Table 9 shows the relationship between fan speed and time
per revolution at 60%, 70%, and 100% of nominal RPM for
fan speeds of 1100, 2200, 4400, and 8800 RPM, and the
divisor that would be used for each of these fans, based on
two tach pulses per revolution.
Limit Values
Fans generally do not over-speed if run from the correct
voltage, so the failure condition of interest is under speed
due to electrical or mechanical failure. For this reason, only
low speed limits are programmed into the limit registers for
the fans. It should be noted that because fan period rather
than speed is being measured, a fan failure interrupt occurs
when the measurement exceeds the limit value.
509
D
0.05 ms
(eq. 17)
where:
509 is the total number of clock pulses.
D is the divisor: 1, 2, 4, or 8.
0.05 ms is the worst-case oscillator period in ms.
The worst-case fan monitoring cycle time is the sum of the
worst-case measurement time for each fan.
Although the fan monitoring cycle and the analog input
monitoring cycle are started together, they are not
synchronized in any other way.
Fan Monitoring Cycle Time
The fan speeds are measured in sequence from 0 to 7. The
monitoring cycle time depends on the fan speed, the number
of tach output pulses per revolution, and the number of fans
being monitored.
If a fan is stopped or running so slowly that the fan speed
counter reaches 255 before the second tach pulse after
Table 9. FAN SPEEDS AND DIVISORS
Time Per
Divisor RPM
Nominal Rev
RPM (ms)
70% RPM
Rev 70% (ms)
60% RPM
1
8800
6.82
6160
9.74
5280
11.36
2
4400
13.64
3080
19.48
2640
22.73
4
2200
27.27
1540
38.96
1320
45.45
8
1100
54.54
770
77.92
660
90.9
Chassis Intrusion Input
Rev 60% (ms)
The chassis intrusion input can also be used for other types
of alarm input. Figure 48 shows a temperature alarm circuit
using an AD22105 temperature switch sensor. This
produces a low-going output when the preset temperature is
exceeded, so the output is inverted by Q1 to make it
compatible with the CI input. Q1 can be almost any
small-signal NPN transistor, or a TTL or CMOS inverter
gate may be used if one is available.
The chassis intrusion input is an active high input intended
for detection and signaling of unauthorized tampering with
the system. When this input goes high, the event is latched
in Bit 6 of Status Register 4, and an interrupt is generated.
The bit remains set until cleared by writing a 1 to CI clear,
Bit 1 of Configuration Register 3 (05h), as long as battery
voltage is connected to the VBAT input. The CI clear bit itself
is cleared by writing a 0 to it.
The CI input detects chassis intrusion events even when
the ADM1026 is powered off (provided battery voltage is
applied to VBAT) but does not immediately generate an
interrupt. Once a chassis intrusion event is detected and
latched, an interrupt is generated when the system is
powered on.
The actual detection of chassis intrusion is performed by
an external circuit that detects, for example, when the cover
has been removed. A wide variety of techniques may be used
for the detection, for example:
 A Microswitch that Opens or Closes when the Cover is
Removed
 A Reed Switch Operated by Magnet Fixed to the Cover
 A Hall-effect Switch Operated by Magnet Fixed to the
Cover
 A Phototransistor that Detects Light when the Cover is
Removed
6
RSET
7
AD22105
TEMPERATURE
SENSOR
1
3
R1
10k
VCC
CI
18
Q1
2
Figure 48. Using the CI Input with a Temperature Sensor
General-Purpose I/O Pins (Open Drain)
The ADM1026 has eight pins that are dedicated to
general-purpose logic input/output (Pins 1, 2, and 43 to 48),
eight pins that can be configured as general-purpose logic
pins or fan speed inputs (Pins 3 to 6, and 9 to 12), and one
pin that can be configured as GPIO16 or the bidirectional
THERM pin (Pin 42). The GPIO/FAN pins are configured
as general-purpose logic pins by setting Bits 0 to 7 of
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ADM1026
Analog/Temperature Inputs
Configuration Register 2 (Address 01h). Pin 42 is
configured as GPIO16 by setting Bit 0 of Configuration
Register 3, or as the THERM function by clearing this bit.
Each GPIO pin has four data bits associated with it, two
bits in one of the GPIO configuration registers (Addresses
08h to 0Bh), one in the GPIO status registers (Addresses 24h
and 25h), and one in the GPIO mask registers (Addresses
1Ch and 1Dh)
Setting a direction bit = 1 in one of the GPIO configuration
registers makes the corresponding GPIO pin an output.
Clearing the direction bit to 0 makes it an input.
Setting a polarity bit = 1 in one of the GPIO configuration
registers makes the corresponding GPIO pin active high.
Clearing the polarity bit to 0 makes it active low.
When a GPIO pin is configured as an input, the
corresponding bit in one of the GPIO status registers is
read-only, and is set when the input is asserted (“asserted” may
be high or low depending on the setting of the polarity bit).
When a GPIO pin is configured as an output, the
corresponding bit in one of the GPIO status registers
becomes read/write. Setting this bit then asserts the GPIO
output. (Here again, “asserted” may be high or low
depending on the setting of the polarity bit.)
The effect of a GPIO status register bit on the INT output
can be masked out by setting the corresponding bit in one of
the GPIO mask registers. When the pin is configured as an
output, this bit is automatically masked to prevent the data
written to the status bit from causing an interrupt, with the
exception of GPIO16, which must be masked manually by
setting Bit 7 of Mask Register 4 (Reg 1Bh).
When configured as inputs, the GPIO pins may be
connected to external interrupt sources such as temperature
sensors with digital output. Another application of the GPIO
pins would be to monitor a processor’s voltage ID code (VID
code).
As each analog measurement value is obtained and stored
in the appropriate value register, the value and the limits
from the corresponding limit registers are fed to the high and
low limit comparators. The device performs greater than
comparisons to the high limits. An out-of-limit is also
generated if a result is less than or equal to a low limit. The
result of each comparison (1 = out of limit, 0 = in limit) is
routed to the corresponding bit input of Interrupt Status
Register 1, 2, or 4 via a data de-multiplexer, and used to set
that bit high or low as appropriate. Status bits are
self-clearing. If a bit in a status register is set due to an
out-of-limit measurement, it continues to cause INT to be
asserted as long as it remains set, as described later.
However, if a subsequent measurement is in limit, it is reset
and does not cause INT to be reasserted. Status bits are
unaffected by clearing the interrupt.
Interrupt Mask Registers 1, 2, and 4 have bits
corresponding to each of the interrupt status register bits.
Setting an interrupt mask bit high conceals an asserted status
bit from display on Interrupt Pin 17. Setting an interrupt
mask bit low allows the corresponding status bit to be
asserted and displayed on Pin 17. After mask gating, the
status bits are all OR’ed together to produce the analog and
fan interrupt that is used to set a latch. The output of this latch
is OR’ed with other interrupt sources to produce the INT
output. This pulls low if any unmasked status bit goes high,
that is, when any measured value goes out of limit.
When an INT output caused by an out-of-limit analog/
temperature measurement is cleared by one of the methods
described later, the latch is reset. It is not set again, and INT
is not reasserted until after two local temperature
measurements have been taken, even if the status bit remains
set or a new analog/temperature event occurs, as shown in
Figure 49. This delay corresponds to almost two monitoring
cycles, and is about 530 ms. However, interrupts from other
sources such as a fan or GPIO can still occur. This is
illustrated in Figure 50.
ADM1026 Interrupt Structure
The Interrupt Structure of the ADM1026 is shown in
Figure 52. Interrupts can come from a number of sources,
which are combined to form a common INT output. When
INT is asserted, this output pulls low. The INT pin has an
internal, 100 kW pullup resistor.
START OF ANALOG
OUT-OF-LIMIT
MONITORING
MEASUREMENT
CYCLE
INT CLEARED
LOCAL
TEMPERATURE
MEASUREMENT
START OF ANALOG
MONITORING
CYCLE
OUT-OF-LIMIT
MEASUREMENT
LOCAL
TEMPERATURE
MEASUREMENT
INT
START OF ANALOG
MONITORING
CYCLE
INT RE−ASSERTED
FULL MONITORING CYCLE = 273ms
Figure 49. Delay After Clearing INT Before Reassertion
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ADM1026
START OF ANALOG OUT-OF-LIMIT
MONITORING CYCLE MEASUREMENT
INT
CLEARED
LOCAL TEMPEREATURE START OF ANALOG
MEASUREMENT
MONITORING CYCLE
INT
CLEARED
LOCAL TEMPERATURE
MEASUREMENT
START OF ANALOG
MONITORING CYCLE
GPIO DE−ASSERTED
INT
INT RE−ASSERTED
NEW INT
FROM FAN
NEW INT
FROM GPIO
Figure 50. Other Interrupt Sources Can Reassert INT Immediately
Registers 5 and 6, or Bit 7 of Status Register 4 (GPIO16). A
chassis intrusion event sets Bit 6 of Status Register 4.
The GPIO and CI status bits, after mask gating, are OR’ed
together and OR’ed with other interrupt sources to produce
the INT output. GPIO and CI interrupts are not latched and
cannot be cleared by normal interrupt clearing. They can
only be cleared by masking the status bits or by removing the
source of the interrupt.
Status Register 4 also stores inputs from two other
interrupt sources that operate in a different way from the
other status bits. If automatic fan speed control (AFC) is
enabled, Bit 4 of Status Register 4 is set whenever a fan starts
or stops. This bit causes a one-off INT output as shown in
Figure 51. It is cleared during the next monitoring cycle and
if INT has been cleared, it does not cause INT to be
reasserted.
FAN ON
Enabling and Clearing Interrupts
FAN OFF
The INT output is enabled when Bit 1 of Configuration
Register 1 (INT_Enable) is high, and Bit 2 (INT_Clear) is
low. INT may be cleared if:
 Status Register 1 is read. Ideally, if polling the status
registers trying to identify interrupt sources, Status
Register 1 should be polled last, because a read of Status
Register 1 clears all the other interrupt status registers.
 The ADM1026 receives the alert response address
(ARA) (0001 100) over the SMBus.
 Bit 2 of Configuration Register 1 is set.
INT
INT CLEARED BY STATUS REGULAR 1 READ, BIT 2
OF CONFIGURATION REGULAR 1 SET, OR ARA
Figure 51. Assertion of INT Due to AFC Event
In a similar way, a change of state at the THERM output
(described in more detail later), sets Bit 3 of Status
Register 4 and causes a one-off INT output. A change of
state at the THERM output also causes Bit 0 of Status
Register 1, Bit 1 of Status Register 1, or Bit 0 of Status
Register 4 to be set, depending on which temperature
channel caused the THERM event. This bit is reset during
the next monitoring cycle, provided the temperature channel
is within the normal high and low limits.
Bidirectional THERM Pin
The ADM1026 has a second interrupt pin (GPIO16/
THERM Pin 42) that responds only to critical thermal
events. The THERM pin goes low whenever a THERM limit
is exceeded. This function is useful for CPU throttling or
system shutdown. In addition, whenever THERM is
activated, the PWM and DAC outputs go full scale to
provide fail-safe system cooling. This output is enabled by
setting Bit 4 of Configuration Register 1 (Register 00h).
Whenever a THERM limit is exceeded, Bit 3 of Status
Register 4 (Reg 23h) is set, even if the THERM function is
disabled (Bit 4 of Configuration Register 1 = 0). In this case,
the THERM status bit is set, but the PWM and DAC outputs
are not forced to full scale.
Three thermal limit registers are provided for the three
temperature sensors at Addresses 0Dh to 0Fh. These registers
are dedicated to the THERM function and none of the other
limit registers have any effect on the THERM output.
If any of the temperature measurements exceed the
corresponding limit, THERM is asserted (low) and the DAC
and PWM outputs go to maximum to drive any cooling fans
to full speed.
To avoid cooling fans cycling on and off continually when
the temperature is close to the limit, a fixed hysteresis of 5C
Fan Inputs
Fan inputs generate interrupts in a similar way to
analog/temperature inputs, but as the analog/temperature
inputs and fan inputs have different monitoring cycles, they
have separate interrupt circuits. As the speed of each fan is
measured, the output of the fan speed counter is stored in a
value register. The result is compared to the fan speed limit
and is used to set or clear a bit in Status Register 3. In this
case, the fan is monitored only for underspeed (fan counter
> fan speed limit). Mask Register 3 is used to mask fan
interrupts. After mask gating, the fan status bits are OR’ed
together and used to set a latch, whose output is OR’ed with
other interrupt sources to produce the INT output.
Like the analog/temp interrupt, an INT output caused by an
out−of−limit fan speed measurement, once cleared, is not
reasserted until the end of the next monitoring cycle, although
other interrupt sources may cause INT to be asserted.
GPIO and CI Pins. When GPIO pins are configured as
inputs, asserting a GPIO input (high or low, depending on
polarity) sets the corresponding GPIO status bit in Status
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ADM1026
if INT is subsequently cleared by one of the methods
previously described, it is not reasserted, even if THERM
remains asserted. THERM causes INT to be reasserted only
when it changes state.
is provided. THERM is only deasserted when the measured
temperature of all three sensors is 5C below the limit.
Whenever the THERM output changes, INT is asserted,
as shown in Figure 53. However, this is edge-triggered, so
LOW LIMIT
AIN3
AIN4
AIN5
AIN6
AIN7
MASK DATA FROM
SMBus (SAME BIT
NAMES AND ORDER
AS STATUS BITS)
INT TEMP
VBAT
AIN8
THERM
AFC
RESERVED
CI
GPIO16
FROM FAN SPEED
VALUE AND
LIMIT REGISTERS
HIGH LIMIT
1 = OUT
OF LIMIT
FAN0
FAN1
FAN2
FAN3
FAN4
FAN5
FAN6
FAN7
DATA
DEMULTIPLEXER
VALUE
HIGH LIMIT
COMPARATOR
MASK DATA FROM
SMBus (SAME BIT
NAMES AND ORDER
AS STATUS BITS)
MASK DATA FROM
SMBus (SAME BIT
NAMES AND ORDER
AS STATUS BITS)
STATUS
REGISTER
1
STATUS
BIT
MASK
BIT
MASK
REGISTER
1
0
1
2
3
4
5
6
7
MASK GATING
STATUS
REGISTER
2
VALUE
1 = OUT
OF LIMIT
AIN0
AIN1
AIN2
DATA
DEMULTIPLEXER
HIGH LIMIT
HIGH AND
LOW LIMIT
COMPARATORS
FROM ANALOG/TEMP
VALUE AND LIMIT
REGISTERS
MASK GATING
STATUS
BIT
IN OUT
LATCH
MASK
BIT
RESET
MASK
REGISTER
2
0
1
2
3
4
5
6
7
MASK GATING
STATUS
REGISTER
4
MASK DATA FROM
SMBus (SAME BIT
NAMES AND ORDER
AS STATUS BITS)
0
1
2
3
4
5
6
7
STATUS
BIT
MASK
BIT
MASK
REGISTER
4
0
1
2
3
4
5
6
7
CI
GPIO16
MASK GATING
STATUS
REGISTER
3
EXT1 TEMP
EXT 2 TEMP
3.3V STBY
3.3V MAIN
+5V
VCCP
+12V
–12V
STATUS
BIT
MASK
BIT
MASK
REGISTER
3
STATUS REGISTER 5
MASKING DATA
FROM SMBus
MASK REGISTER 5
GPIO8 TO GPIO15
STATUS REGISTER 6
MASKING DATA
FROM SMBus
MASK REGISTER 6
STATUS
BIT
MASK
BIT
MASK GATING
STATUS
BIT
MASK
BIT
Figure 52. Interrupt Structure
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28
LATCH
RESET
INT ENABLE
MASK GATING
GPIO0 TO GPIO7
INT
IN OUT
INT CLEAR
ADM1026
NAND Tree Tests
Note that the THERM pin is bidirectional, so THERM
may be pulled low externally as an input. This causes the
PWM and DAC outputs to go to full scale until THERM is
returned high again. To disable THERM as an input, set Bit 0
of Configuration Register 3 (Reg. 07h). This configures
Pin 42 as GPIO16 and prevents a low on Pin 42 from driving
the fans at full speed.
A NAND tree is provided in the ADM1026 for automated
test equipment (ATE) board-level connectivity testing. This
allows the functionality of all digital inputs to be tested in a
simple manner and any pins that are nonfunctional or
shorted together to be identified. The structure of the NAND
tree is shown in Figure 55. The device is placed into NAND
tree test mode by powering up with Pin 25 held high. This
pin is sampled automatically after powerup, and if it is
connected high, then the NAND test mode is invoked.
TEMPERATURE
THERM LIMIT
THERM LIMIT - 55C
GPIO8
THERM
FAN0
FAN1
INT
FAN2
INT CLEARED BY STATUS REG 1 READ,
BIT 2 OF CONFIG. REG. 1 SET, OR ARA
INT
Figure 53. Assertion of INT Due to THERM Event
CI
Reset Input and Outputs
SDA
The ADM1026 has two active low, power-on reset
outputs, RESETMAIN and RESETSTBY. These operate as
follows.
RESETSTBY monitors 3.3 V STBY. At powerup,
RESETSTBY is asserted (pulled low) until 180 ms after
3.3 V STBY rises above the reset threshold.
RESETMAIN monitors 3.3 V MAIN. This means that at
powerup, RESETMAIN is asserted (pulled low) until
180 ms after 3.3 V MAIN rises above the reset threshold.
If 3.3 V MAIN rises with or before DVCC, RESETMAIN
remains asserted until 180 ms after RESETSTBY is
negated. RESETMAIN can also function as a RESET input.
Pulling this pin low resets the registers, which are initialized
to their default values by a software reset. (See the Software
Reset Function section for register details).
Note that the 3.3 V STBY pin supplies power to the
ADM1026. In applications that do not require monitoring of
a 3.3 V STBY and 3.3 V MAIN supply, these two pins should
be connected together (3.3 V MAIN should not be left
floating).
To ensure that the 3.3 V STBY pin does not become back
driven, the 3.3 V STBY supply should power on before all
other voltages in the system.
See Table 5 for more information about pin configuration.
3.3VSTBY
3.3VMAIN
SCL
FAN7
FAN4
FAN5
FAN6
GPIO10
GPIO11
GPIO12
GPIO13
GPIO14
GPIO15
GPIO16
NTESTOUT
Figure 55. NAND Tree
The NAND tree test may be carried out in one of two
ways.
1. Start with all inputs low and take them high in
turn, starting with the input nearest to
NTEST_OUT (GPIO16/ THERM) and working
back up the tree to the input furthest from
NTESTOUT (INT). This should give the
characteristic output pattern shown in Figure 56,
with NTESTOUT toggling each time an input is
taken high.
2. Start with all inputs high and take them low in
turn, starting with the input furthest from
NTEST_OUT (INT) and working down the tree to
the input nearest to NTEST_OUT
(GPIO16/THERM). This should give a similar
output pattern to Figure 57.
~1.0 V
~1.0 V
RESETSTBY
RESETMAIN
180ms
FAN3
GPIO9
180ms
POWER−ON RESET
Figure 54. Operation of Offset Outputs
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ADM1026
Notes:
 For a NAND tree test to work, all outputs (INT,
RSTMAIN, RSTSTBY, and PWM) must remain high
during the test.
 When generating test waveforms, allow for a typical
propagation delay of 500 ns through the NAND tree.
 If any of the inputs shown in Figure 55 are unused, they
should not be connected direct to ground, but via a
resistor such as 10 kW. This allows the automatic test
equipment (ATE) to drive every input high so that the
NAND tree test can be properly carried out.
INT
CI
SDA
SCL
FAN7
FAN6
FAN5
FAN4
FAN3
FAN2
FAN1
GPIO16
FAN0
GPIO15
GPIO8
GPIO14
GPIO9
GPIO13
GPIO10
GPIO12
GPIO11
GPIO11
GPIO12
GPIO10
GPIO13
GPIO9
GPIO14
GPIO8
GPIO15
FAN0
GPIO16
FAN1
NTESTOUT
FAN2
Figure 57. NAND Tree Test Taking Inputs Low in Turn
FAN3
FAN4
FAN5
GPIO16
FAN6
GPIO15
FAN7
GPIO14
SCL
GPIO13
SDA
GPIO12
CI
GPIO11
INT
GPIO10
GPIO9
NTESTOUT
GPIO8
FAN0
Figure 56. NAND Tree Test Taking Inputs High in Turn
FAN1
NTESTOUT
In the event of an input being nonfunctional (stuck high or
low) or two inputs shorted together, the output pattern is
different. Some examples are given in Figure 58 through
Figure 60.
Figure 58 shows the effect of one input being stuck low.
The output pattern is normal until the stuck input is reached.
Because that input is permanently low, neither it nor any
inputs further up the tree can have any effect on the output.
Figure 58. NAND Tree Test with GPIO11 Stuck Low
Figure 59 shows the effect of one input being stuck high.
Taking GPIO12 high should take the output high. However,
the next input up the tree, GPIO11, is already high, so the
output immediately goes low again, causing a missing pulse
in the output pattern.
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ADM1026
 Setting the fan divisors using the fan divisor registers
GPIO16
GPIO15

GPIO14
GPIO13
GPIO12

GPIO11
GPIO10

GPIO9
GPIO8
(Addresses 02h and 03h).
Configuring the GPIO pins for input/output polarity, using
GPIO Configuration Registers 1 to 4 (Addresses 08h to
0Bh) and Bits 6 and 7 of Configuration Register 3.
Setting mask bits in Mask Registers 1 to 6 (Addresses
18h to 1Dh) for any inputs that are to be masked out.
Setting up Configuration Registers 1 and 3, as
described in Table 10 and Table 11.
FAN0
Table 10. CONFIGURATION REGISTER 1
FAN1
Bit
Description
0
Controls the monitoring loop of the ADM1026. Setting
Bit 0 low stops the monitoring loop and puts the
ADM1026 into low power mode and reduces power
consumption. Serial bus communication is still
possible with any register in the ADM1026 while in
low power mode. Setting bit 0 high starts the
monitoring loop.
1
Enables or disables the INT interrupt output. Setting
Bit 1 high enables the INT output, setting Bit 1 low
disables the output.
2
Used to clear the INT interrupt output when set high.
GPIO pins and interrupt status register contents are
not affected.
3
Configures Pins 27 and 28 as the second external
temperature channel when 0, and as AIN8 and AIN9
when set to 1.
GPIO13
4
Enables the THERM output when set to 1.
GPIO12
5
Enables automatic fan speed control on the DAC
output when set to 1.
6
Enables automatic fan speed control on the PWM
output when set to 1.
7
Performs a soft reset when set to 1.
NTESTOUT
Figure 59. NAND Tree Test with One Input Stuck High
A similar effect occurs if two adjacent inputs are shorted
together. The example in Figure 60 assumes that the current
sink capability of the circuit driving the inputs is
considerably higher than the source capability, so the inputs
are low if either is low, but high only if both are high.
When GPIO12 goes high the output should go high. But
because GPIO12 and GPIO11 are shorted, they both go high
together, causing a missing pulse in the output pattern.
GPIO16
GPIO15
GPIO14
GPIO11
GPIO10
GPIO9
GPIO8
FAN0
Table 11. CONFIGURATION REGISTER 3
FAN1
Bit
NTESTOUT
Figure 60. NAND Tree Test with Two Inputs Shorted
Using the ADM1026
When power is first applied, the ADM1026 performs a
power−on reset on all its registers (not EEPROM), which
sets them to default conditions as shown in Table 13. In
particular, note that all GPIO pins are configured as inputs
to avoid possible conflicts with circuits trying to drive these
pins.
The ADM1026 can also be initialized at any time by
writing a 1 to Bit 7 of Configuration Register 1, which sets
some registers to their default power−on conditions. This bit
should be cleared by writing a 0 to it.
After power−on, the ADM1026 must be configured to the
user’s specific requirements. This consists of:
 Writing values to the limit registers.
 Configuring Pins 3 to 6, and 9 to 12 as fan inputs or
GPIO, using Configuration Register 2 (Address 01h).
Description
0
Configures Pin 42 as GPIO when set to 1 or as
THERM when cleared to 0.
1
Clears the CI latch when set to 1. Thereafter, a 0
must be written to allow subsequent CI detection.
2
Selects VREF as 2.5 V when set to 1 or as 1.82 V
when cleared to 0.
3–5
Unused.
6, 7
Set up GPIO16 for direction and polarity.
Starting Conversion
The monitoring function (analog inputs, temperature, and
fan speeds) in the ADM1026 is started by writing to
Configuration Register 1 and setting Start (Bit 0) high. The
INT_Enable (Bit 1) should be set to 1, and INT Clear (Bit 2)
set to 0 to enable interrupts. The THERM enable bit (Bit 4)
should be set to 1 to enable temperature interrupts at the
THERM pin. Apart from initially starting together, the
analog measurements and fan speed measurements proceed
independently, and are not synchronized in any way.
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ADM1026
Reduced Power Mode
Note that the limit registers (0Dh to 12h, 40h to 6Dh) are
not reset by the software reset function. This can be useful
if one needs to reset the part but does not want to reprogram
all parameters again. Note that a power-on reset initializes
all registers on the ADM1026, including the limit registers.
The ADM1026 can be placed in a low power mode by
setting Bit 0 of the configuration register to 0. This disables
the internal ADC.
Software Reset Function
As previously mentioned, the ADM1026 can be reset in
software by setting Bit 7 of Configuration Register 1
(Reg. 00h) to 1. Configuration Register 1, 00h, should then
be manually cleared. Note that the software reset differs
from a power-on reset in that only some of the ADM1026
registers are reinitialized to their power-on default values.
The registers that are initialized to their default values by the
software reset are
 Configuration Registers (Registers 01h to 0Bh)
 Mask Registers 1 to 6, internal temperature offset, and
Status Registers 4, 5, and 6 (Registers 18h to 25h)
 All value registers (Registers 1Fh, 20h to 3Fh)
 External 1 and External 2 Offset Registers (6Eh, 6Fh)
Application Schematic
Figure 61 shows how the ADM1026 could be used in an
application that requires system management of a PC or
server. Several GPIOs are used to read the VID codes of the
CPU. Up to two CPU temperature measurements can be read
back. All power supply voltages are monitored in the
system. Up to eight fan speeds can be measured, irrespective
of whether they are controlled by the ADM1026 or
hardwired to a system supply. The VREF output includes the
recommended filtering circuitry.
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X5
Figure 61. ADM1026 Schematic
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33
FAN
3
Q1
SDATA
SCLOCK
46 GPIO12
R2
2k
12
DAC 23
3.3V STBY 22
AGND 21
2
R1
2k
FAN7/GPIO7
D1– 25
D1+ 26
D2–/A IN9 27
D2+/A IN8 28
+VBAT 29
–12V IN 31
+5 VIN 30
AIN7 34
+VCCP 33
+12 VIN 32
AIN5 36
AIN6 35
R3
470k
R6
10k
CPU1_THERMDC
CPU1_THERMDA
CPU2_THERMDC
CPU2_THERMDA
+5 VIN
–12 VIN
CPU1_VCCP
+12 VIN
CPU2_VCCP
SYS_THERM
4
1
3.3V STDY
FAN6/GPIO6
FAN5/GPIO5
11
10
9 FAN4/GPIO4
45 GPIO13
+12V
3
3
FAN
2
2
1
44 GPIO14
8 DGND
42 THERM
43 GPIO15
U1
ADM1026_SKT
41 A
IN0
7 3.3VMAIN
6 FAN3/GPIO3
5 FAN2/GPIO2
4 FAN1/GPIO1
38 A
IN3
1
+12V
48 GPIO10
+12V
X4
FAN
47 GPIO11
3 FAN0/GPIO0
1 GPIO9
2 GPIO8
39 A
IN2
40 A
IN1
FAN
FAN
3
3
1
+12V
2
X2
2
1
+12V
37 A
IN4
X3
X1
CPU1_VID4
CPU1_VID3
CPU1_VID2
CPU1_VID1
CPU1_VID0
R5
10k
C1
0.1F
R4
10k
VCC
+
B1
SMB_ALERT
CPURESET
POWER_GOOD
0–2.5V_OUT
VREF_OUT
ADM1026
S1
1
VREF 24
3.3V_STBY
RESETSTBY 19
PWM 18
RESETMAIN 20
INT 17
ADD 15
CI 16
SDA 14
SCL 13
ADM1026
Registers
Table 12. ADDRESS POINTER REGISTER
Bit
Name
R/W
7–0
Address Pointer
W
Description
Address of ADM1026 registers. See the following tables for details.
Table 13. LIST OF REGISTERS
Hex
Address
Name
Power-on
Value
Description
00
Configuration 1
00h
Configures various operating parameters .
01
Configuration 2
00h
Configures Pins 3–6 and 9–12 as fan inputs or GPIO.
02
Fan 0–3 Divisor
55h
Sets oscillator frequency for Fan 0–3 speed measurement.
03
Fan 4–7 Divisor
55h
Sets oscillator frequency for Fan 4–7 speed measurement.
04
DAC Control
FFh
Contains value for fan speed DAC (analog fan speed control) or minimum value
for automatic fan speed control.
05
PWM Control
FFh
Contains value for PWM fan speed control or minimum value for automatic fan
speed control.
06
EEPROM Register
100h
For factory use only.
07
Configuration Register
300h
Configuration register for THERM, VREF and GPIO16.
08
GPIO Config 1
00h
Configures GPIO0 to GPIO3 as input or output and as active high or active low.
09
GPIO Config 2
00h
Configures GPIO4 to GPIO7 as input or output and as active high or active low.
0A
GPIO Config 3
00h
Configures GPIO8 to GPIO11 as input or output and as active high or active low.
0B
GPIO Config 4
00h
Configures GPIO12 to GPIO15 as input or output and as active high or active low.
0C
EEPROM Register 2
00h
For factory use only.
0D
Int Temp THERM Limit
37h (55C)
High limit for THERM interrupt output based on internal temperature
measurement.
0E
TDM1 THERM Limit
50h (80C)
High limit for THERM interrupt output based on Remote Channel 1 (D1)
temperature measurement.
0F
TDM2 THERM Limit
50h (80C)
High limit for THERM interrupt output based on Remote Channel 2 (D2)
temperature measurement.
10
Int Temp TMIN
28h (40C)
TMIN value for automatic fan speed control based on internal temperature
measurement.
11
TDM1 TMIN
40h (64C)
TMIN value for automatic fan speed control based on Remote Channel 1 (D1)
temperature measurement.
12
TDM2 TMIN
40h (64C)
TMIN value for automatic fan speed control based on Remote Channel 2 (D2)
temperature measurement.
13
EEPROM Register 3
00h
Configures EEPROM for read/write/erase, etc.
14
Test Register 1
00h
Manufacturer’s test register.
15
Test Register 2
00h
For manufacturer’s use only.
16
Manufacturer’s ID
41h
Contains manufacturer’s ID code.
17
Revision
4xh
Contains code for major and minor revisions.
18
Mask Register 1
00h
Interrupt mask register for temperature and supply voltage faults.
19
Mask Register 2
00h
Interrupt mask register for analog input faults.
1A
Mask Register 3
00h
Interrupt mask register for fan faults.
1B
Mask Register 4
00h
Interrupt mask register for local temp, VBAT, AIN8, THERM, AFC, CI and GPIO16.
1C
Mask Register 5
00h
Interrupt mask register for GPIO0 to GPIO7.
1D
Mask Register 6
00h
Interrupt mask register for GPIO8 to GPIO15.
1E
Int Temp Offset
00h
Offset register for internal temperature measurement.
1F
Int Temp Value
00h
Measured temperature from on-chip sensor.
20
Status Register 1
00h
Interrupt status register for external temp and supply voltage faults.
21
Status Register 2
00h
Interrupt status register for analog input faults.
22
Status Register 3
00h
Interrupt status register for fan faults.
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ADM1026
Table 13. LIST OF REGISTERS
Hex
Address
Name
Power-on
Value
Description
23
Status Register 4
00h
Interrupt status register for local temp, VBAT, AIN8, THERM, AFC, CI, and GPIO16.
24
Status Register 5
00h
Interrupt status register for GPIO0 to GPIO7.
25
Status Register 6
00h
Interrupt status register for GPIO8 to GPIO15.
26
VBAT Value
00h
Measured value of VBAT.
27
AIN8 Value
00h
Measured value of AIN8.
28
TDM1 Value
00h
Measured value of remote temperature channel 1 (D1).
29
TDM2/AIN9 Value
00h
Measured value of remote temperature channel 2 (D2) or AIN9.
2A
3.3 V STBY Value
00h
Measured value of 3.3 V STBY.
2B
3.3 V MAIN Value
00h
Measured value of 3.3 V MAIN.
2C
+5.0 V Value
00h
Measured value of +5.0 V supply.
2D
VCCP Value
00h
Measured value of processor core voltage.
2E
+12 V Value
00h
Measured value of +12 V supply.
2F
−12 V Value
00h
Measured value of -12 V supply.
30
AIN0 Value
00h
Measured value of AIN0.
31
AIN1 Value
00h
Measured value of AIN1
32
AIN2 Value
00h
Measured value of AIN2.
33
AIN3 Value
00h
Measured value of AIN3.
34
AIN4 Value
00h
Measured value of AIN4.
35
AIN5 Value
00h
Measured value of AIN5.
36
AIN6 Value
00h
Measured value of AIN6.
37
AIN7 Value
00h
Measured value of AIN7.
38
FAN0 Value
00h
Measured speed of Fan 0.
39
FAN1 Value
00h
Measured speed of Fan 1.
3A
FAN2 Value
00h
Measured speed of Fan 2.
3B
FAN3 Value
00h
Measured speed of Fan 3.
3C
FAN4 Value
00h
Measured speed of Fan 4.
3D
FAN5 Value
00h
Measured speed of Fan 5.
3E
FAN6 Value
00h
Measured speed of Fan 6.
3F
FAN7 Value
00h
Measured speed of Fan 7.
40
TDM1 High Limit
64h (100C)
High limit for Remote Temperature Channel 1 (D1) measurement.
41
TDM2/AIN9 High Limit
64h (100C)
High limit for Remote Temperature Channel 2 (D2) or AIN9 measurement.
42
3.3 V STBY High Limit
FFh
High limit for 3.3 V STBY measurement.
43
3.3 V MAIN High Limit
FFh
High limit for 3.3 V MAIN measurement.
44
+5.0 V High Limit
FFh
High limit for +5.0 V supply measurement.
45
VCCP High Limit
FFh
High limit for processor core voltage measurement.
46
+12 V High Limit
FFh
High limit for +12 V supply measurement.
47
−12 V High Limit
FFh
High limit for -12 V supply measurement.
48
TDM1 Low Limit
80h
Low limit for Remote Temperature Channel 1 (D1) measurement.
49
TDM2/AIN9 Low Limit
80h
Low limit for Remote Temperature Channel 2 (D2) or AIN9 measurement.
4A
3.3 V STBY Low Limit
00h
Low limit for 3.3 V STBY measurement.
4B
3.3 V MAIN Low Limit
00h
Low limit for 3.3 V MAIN measurement.
4C
+5.0 V Low Limit
00h
Low limit for +5.0 V supply.
4D
VCCP Low Limit
00h
Low limit for processor core voltage measurement.
4E
+12 V Low Limit
00h
Low limit for +12 V supply measurement.
4F
−12 V Low Limit
00h
Low limit for -12 V supply measurement.
50
AIN0 High Limit
FFh
High limit for AIN0 measurement.
51
AIN1 High Limit
FFh
High limit for AIN1 measurement.
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ADM1026
Table 13. LIST OF REGISTERS
Hex
Address
Name
Power-on
Value
Description
52
AIN2 High Limit
FFh
High limit for AIN2 measurement.
53
AIN3 High Limit
FFh
High limit for AIN3 measurement.
54
AIN4 High Limit
FFh
High limit for AIN4 measurement.
55
AIN5 High Limit
FFh
High limit for AIN5 measurement.
56
AIN6 High Limit
FFh
High limit for AIN6 measurement.
57
AIN7 High Limit
FFh
High limit for AIN7 measurement.
58
AIN0 Low Limit
00h
Low limit for AIN0 measurement.
59
AIN1 Low Limit
00h
Low limit for AIN1 measurement.
5A
AIN2 Low Limit
00h
Low limit for AIN2 measurement.
5B
AIN3 Low Limit
00h
Low limit for AIN3 measurement.
5C
AIN4 Low Limit
00h
Low limit for AIN4 measurement.
5D
AIN5 Low Limit
00h
Low limit for AIN5 measurement.
5E
AIN6 Low Limit
00h
Low limit for AIN6 measurement.
5F
AIN7 Low Limit
00h
Low limit for AIN7 measurement.
60
FAN0 High Limit
FFh
High limit for Fan 0 speed measurement (no low limit).
61
FAN1 High Limit
FFh
High limit for Fan 1 speed measurement (no low limit).
62
FAN2 High Limit
FFh
High limit for Fan 2 speed measurement (no low limit).
63
FAN3 High Limit
FFh
High limit for Fan 3 speed measurement (no low limit).
64
FAN4 High Limit
FFh
High limit for Fan 4 speed measurement (no low limit).
65
FAN5 High Limit
FFh
High limit for Fan 5 speed measurement (no low limit).
66
FAN6 High Limit
FFh
High limit for Fan 6 speed measurement (no low limit).
67
FAN7 High Limit
FFh
High limit for Fan 7 speed measurement (no low limit).
68
Int. Temp. High Limit
50h (80C)
High limit for local temperature measurement.
69
Int. Temp. Low Limit
80h
Low limit for local temperature measurement.
6A
VBAT High Limit
FFh
High limit for VBAT measurement.
6B
VBAT Low Limit
00h
Low limit for VBAT measurement.
6C
AIN8 High Limit
FFh
High limit for AIN8 measurement.
6D
AIN8 Low Limit
00h
Low limit for AIN8 measurement.
6E
Ext1 Temp Offset
00h
Offset register for Remote Temperature Channel 1.
6F
Ext2 Temp Offset
00h
Offset register for Remote Temperature Channel 2.
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ADM1026
Detailed Register Descriptions
Table 14. REGISTER 00H, CONFIGURATION REGISTER 1 (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Monitor = 0
R/W
When this bit is set the ADM1026 monitors all voltage, temperature and fan
channels in a round robin manner.
1
Int Enable = 0
R/W
When this bit is set, the INT output pin is enabled.
2
Int Clear = 0
R/W
Setting this bit clears an interrupt from the voltage, temperature or fan speed
channels. Because GPIO interrupts are level triggered, this bit has no effect on
interrupts originating from GPIO channels. This bit is cleared by writing a 0 to it. If
in monitoring mode voltages, temperatures and fan speeds continue to be
monitored after writing to this bit to clear an interrupt, so an interrupt may be set
again on the next monitoring cycle.
3
Enable Voltage/Ext2 = 0
R/W
When this bit is 1, the ADM1026 monitors voltage (AIN8 and AIN9) on Pins 28
and 27, respectively. When this bit is 0, the ADM1026 monitors a second thermal
diode temperature channel, D2, on these pins. If the second thermal diode channel
is not being used, it is recommended that the bit be set to 1.
4
Enable THERM = 0
R/W
When this bit is 1, the THERM pin (Pin 42) is asserted (go low) if any of the
THERM limits are exceeded. If THERM is pulled low as an input, the DAC and
PWM outputs are forced to full scale until THERM is taken high.
5
Enable DAC AFC = 0
R/W
When this bit is 1, the DAC output is enabled for automatic fan speed control
(AFC) based on temperature. When this bit is 0, the DAC Output reflects the value
in Reg 04h, the DAC Control Register.
6
Enable PWM AFC = 0
R/W
When this bit is 1, the PWM output is enabled for automatic fan speed control
(AFC) based on temperature. When this bit is 0, the PWM Output reflects the value
in Reg 05h, the PWM Control Register.
7
Software Reset = 0
R/W
Writing a 1 to this bit restores all registers to the power-on defaults. This bit is
cleared by writing a 0 to it. For more info, see the Software Reset Function section.
Table 15. REGISTER 01H, CONFIGURATION REGISTER 2 (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Enable GPIO0/Fan0 = 0
R/W
When this bit is 1, Pin 3 is enabled as a general−purpose I/O pin (GPIO0),
otherwise it is a fan tach measurement input (Fan 0).
1
Enable GPIO1/Fan1 = 0
R/W
When this bit is 1, Pin 4 is enabled as a general−purpose I/O pin (GPIO1),
otherwise it is a fan tach measurement input (Fan 1).
2
Enable GPIO2/Fan2 = 0
R/W
When this bit is 1, Pin 5 is enabled as a general−purpose I/O pin (GPIO2),
otherwise it is a fan tach measurement input (Fan 2).
3
Enable GPIO3/Fan3 = 0
R/W
When this bit is 1, Pin 6 is enabled as a general−purpose I/O pin (GPIO3),
otherwise it is a fan tach measurement input (Fan 3).
4
Enable GPIO4/Fan4 = 0
R/W
When this bit is 1, Pin 9 is enabled as a general−purpose I/O pin (GPIO4),
otherwise it is a fan tach measurement input (Fan 4).
5
Enable GPIO5/Fan5 = 0
R/W
When this bit is 1, Pin 10 is enabled as a general−purpose I/O pin (GPIO5),
otherwise it is a fan tach measurement input (Fan 5).
6
Enable GPIO6/Fan6 = 0
R/W
When this bit is 1, Pin 11 is enabled as a general−purpose I/O pin (GPIO6),
otherwise it is a fan tach measurement input (Fan 6).
7
Enable GPIO7/Fan7 = 0
R/W
When this bit is 1, Pin 12 is enabled as a general−purpose I/O pin (GPIO7),
otherwise it is a fan tach measurement input (Fan 7).
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ADM1026
Table 16. REGISTER 02H, FANS 0 TO 3 FAN DIVISOR REGISTER (POWER-ON DEFAULT 55H)
Bit
Name
R/W
1–0
Fan 0 Divisor
R/W
Description
Sets the oscillator prescaler division ratio for Fan 0 speed measurement. The
division ratios, oscillator frequencies, and typical fan speeds (based on 2 tach
pulses per revolution) are as follows:
Code
Divide
By:
Oscillator
Frequency (kHz)
00
01
10
11
1
2
4
8
22.5
11.25
5.62
2.81
3–2
Fan 1 Divisor
R/W
Same as Fan 0
5–4
Fan 2 Divisor
R/W
Same as Fan 0
7–6
Fan 3 Divisor
R/W
Same as Fan 0
Fan Speed (RPM)
8800, nominal, for count of 153
4400, nominal, for count of 153
2200, nominal, for count of 153
1100, nominal, for count of 153
Table 17. REGISTER 03H, FANS 4 TO 7 FAN DIVISOR REGISTER (POWER-ON DEFAULT 55H)
Bit
Name
R/W
1–0
Fan 4 Divisor
R/W
Description
Sets the oscillator prescaler division ratio for Fan 4 speed measurement. The
division ratios, oscillator frequencies, and typical fan speeds (based on 2 tach
pulses per revolution) are as follows:
Code
Divide By:
Oscillator
Frequency (kHz)
00
01
10
11
1
2
4
8
22.5
11.25
5.62
2.81
3–2
Fan 5 Divisor
R/W
Same as Fan 4
5–4
Fan 6 Divisor
R/W
Same as Fan 4
7–6
Fan 7 Divisor
R/W
Same as Fan 4
Fan Speed (RPM)
8800, nominal, for count of 153
4400, nominal, for count of 153
2200, nominal, for count of 153
1100, nominal, for count of 153
Table 18. REGISTER 04H, DAC CONFIGURATION REGISTER (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
DAC Control
R/W
Description
This register contains the value to which the fan speed DAC is programmed in
normal mode, or the 4 MSBs contain the minimum fan speed in auto fan speed
control mode.
Table 19. REGISTER 05H, PWM CONTROL REGISTER (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–4
PWM Control
R/W
3–0
Unused
R
Description
This register contains the value to which the PWM fan speed is programmed in
normal mode, or the 4 MSBs contain the minimum fan speed in auto fan speed
control mode.
0000 = 0% Duty Cycle
0001 = 7% Duty Cycle
0101 = 33% Duty Cycle
0110 = 40% Duty Cycle
0111 = 47% Duty Cycle
1110 = 93% Duty Cycle
1111 = 100% Duty Cycle
Undefined
Table 20. REGISTER 06H, EEPROM REGISTER 1 (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
7–0
Factory Use
R/W
For factory use only. Do not write to this register.
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ADM1026
Table 21. REGISTER 07H, CONFIGURATION REGISTER 3 (POWER-ON DEFAULT 00H)
Bit
Name
R/W
0
Enable GPIO16/
THERM = 0
R/W
When this bit is 1, Pin 42 is enabled as a general−purpose I/O pin (GPIO16);
otherwise it is the THERM output.
Description
1
CI Clear = 0
R/W
Writing a 1 to this bit clears the CI latch. This bit is cleared by writing a 0 to it.
When this bit is 0, VREF (Pin 24) outputs 1.82 V, otherwise, it outputs 2.5 V.
2
VREF Select = 0
R/W
5–3
Unused
R
6
GPIO16 Direction
R/W
When this bit is 0, GPIO16 is configured as an input; otherwise, it is an output.
7
GPIO16 Polarity
R/W
When this bit is 0, GPIO16 is active low; otherwise, it is active high.
Undefined, reads back 0.
Table 22. REGISTER 08H, GPIO CONFIGURATION REGISTER 1 (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
GPIO0 Direction
R/W
When this bit is 0, GPIO0 is configured as an input; otherwise, it is an output.
1
GPIO0 Polarity
R/W
When this bit is 0, GPIO0 is active low; otherwise it is active high.
2
GPIO1 Direction
R/W
When this bit is 0, GPIO1 is configured as an input; otherwise, it is an output.
3
GPIO1 Polarity
R/W
When this bit is 0, GPIO1 is active low; otherwise it is active high.
4
GPIO2 Direction
R/W
When this bit is 0, GPIO2 is configured as an input; otherwise, it is an output.
5
GPIO2 Polarity
R/W
When this bit is 0, GPIO2 is active low; otherwise, it is active high.
6
GPIO3 Direction
R/W
When this bit is 0, GPIO3 is configured as an input; otherwise, it is an output.
7
GPIO3 Polarity
R/W
When this bit is 0, GPIO3 is active low; otherwise, it is active high.
Table 23. REGISTER 09H, GPIO CONFIGURATION REGISTER 2 (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
GPIO4 Direction
R/W
When this bit is 0, GPIO4 is configured as an input; otherwise, it is an output.
1
GPIO4 Polarity
R/W
When this bit is 0, GPIO4 is active low; otherwise, it is active high.
2
GPIO5 Direction
R/W
When this bit is 0, GPIO5 is configured as an input; otherwise, it is an output.
3
GPIO5 Polarity
R/W
When this bit is 0, GPIO5 is active low; otherwise, it is active high.
4
GPIO6 Direction
R/W
When this bit is 0, GPIO6 is configured as an input; otherwise, it is an output.
5
GPIO6 Polarity
R/W
When this bit is 0, GPIO6 is active low; otherwise, it is active high.
6
GPIO7 Direction
R/W
When this bit is 0, GPIO7 is configured as an input; otherwise, it is an output.
7
GPIO7 Polarity
R/W
When this bit is 0, GPIO7 is active low; otherwise, it is active high.
Table 24. REGISTER 0AH, GPIO CONFIGURATION REGISTER 3 (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
GPIO8 Direction
R/W
When this bit is 0, GPIO8 is configured as an input; otherwise, it is an output.
1
GPIO8 Polarity
R/W
When this bit is 0, GPIO8 is active low; otherwise, it is active high.
2
GPIO9 Direction
R/W
When this bit is 0, GPIO9 is configured as an input; otherwise, it is an output.
3
GPIO9 Polarity
R/W
When this bit is 0, GPIO9 is active low; otherwise, it is active high.
4
GPIO10 Direction
R/W
When this bit is 0, GPIO10 is configured as an input; otherwise, it is an output.
5
GPIO10 Polarity
R/W
When this bit is 0, GPIO10 is active low; otherwise, it is active high.
6
GPIO11 Direction
R/W
When this bit is 0, GPIO11 is configured as an input; otherwise, it is an output.
7
GPIO11 Polarity
R/W
When this bit is 0, GPIO11 is active low; otherwise, it is active high.
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ADM1026
Table 25. REGISTER 0BH, GPIO CONFIGURATION REGISTER 4 (POWER-ON DEFAULT 00H)
Bit
Name
R/W
0
GPIO12 Direction
R/W
When this bit is 0, GPIO12 is configured as an input; otherwise, it is an output.
Description
1
GPIO12 Polarity
R/W
When this bit is 0, GPIO12 is active low; otherwise, it is active high.
2
GPIO13 Direction
R/W
When this bit is 0, GPIO13 is configured as an input; otherwise, it is an output.
3
GPIO13 Polarity
R/W
When this bit is 0, GPIO13 is active low; otherwise, it is active high.
4
GPIO14 Direction
R/W
When this bit is 0, GPIO14 is configured as an input; otherwise, it is an output.
5
GPIO14 Polarity
R/W
When this bit is 0, GPIO14 is active low; otherwise, it is active high.
6
GPIO15 Direction
R/W
When this bit is 0, GPIO15 is configured as an input; otherwise, it is an output.
7
GPIO15 Polarity
R/W
When this bit is 0, GPIO15 is active low; otherwise, it is active high.
Table 26. REGISTER 0CH, EEPROM CONFIGURATION REGISTER 2 (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
Factory Use
R
Description
For factory use only. Do not write to this register.
Table 27. REGISTER 0DH, INTERNAL TEMPERATURE THERM LIMIT (POWER-ON DEFAULT, 37H 555C)
Bit
Name
R/W
7–0
Int Temp THERM Limit
R/W
Description
This register contains the THERM limit for the internal temperature channel.
Exceeding this limit causes the THERM output pin to be asserted.
Table 28. REGISTER 0EH, TDM1 THERM LIMIT (POWER-ON DEFAULT, 50H 805C)
Bit
Name
R/W
7–0
TDM1 THERM Limit
R/W
Description
This register contains the THERM limit for the TDM1 temperature channel.
Exceeding this limit causes the THERM output pin to be asserted.
Table 29. REGISTER 0FH, TDM2 THERM LIMIT (POWER-ON DEFAULT, 50H 805C)
Bit
Name
R/W
7–0
TDM2 THERM Limit
R/W
Description
This register contains the THERM limit for the TDM2 temperature channel.
Exceeding this limit causes the THERM output pin to be asserted.
Table 30. REGISTER 10H, INTERNAL TEMPERATURE TMIN (POWER-ON DEFAULT, 28H 405C)
Bit
Name
R/W
7–0
Internal Temp TMIN
R/W
Description
This register contains the TMIN value for automatic fan speed control based on the
internal temperature channel.
Table 31. REGISTER 11H, TDM1 TEMPERATURE TMIN (POWER-ON DEFAULT, 40H 645C)
Bit
Name
R/W
7–0
TDM1 Temp TMIN
R/W
Description
This register contains the TMIN value for automatic fan speed control based on the
TDM1 temperature channel.
Table 32. REGISTER 12H, TDM2 TEMPERATURE TMIN (POWER-ON DEFAULT, 40H 645C)
Bit
Name
R/W
7–0
TDM2 Temp TMIN
R/W
Description
This register contains the TMIN value for automatic fan speed control based on the
TDM2 temperature channel.
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ADM1026
Table 33. REGISTER 13H, EEPROM REGISTER 3 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
0
Read
R/W
Setting this bit puts the EEPROM into read mode.
Description
1
Write
R/W
Setting this bit puts the EEPROM in write (program) mode.
2
Erase
R/W
Setting this bit puts the EEPROM into erase mode.
3
Write Protect
R/W
Once
Setting this bit protects the EEPROM against accidental writing or erasure. This bit
can write once and only be cleared by a power−on reset.
4
Test Mode Bit 0
R/W
Test mode bits. For factory use only
5
Test Mode Bit 1
R/W
Test mode bits. For factory use only.
6
Test Mode Bit 2
R/W
Test mode bits. For factory use only
7
Clock Extend
R/W
Setting this bit enables SMBus clock extension. The ADM1026 can pull SCL low to
extend the clock pulse if it cannot accept any more data. It is recommended to set
this bit to 1 to extend the clock pulse during repeated EEPROM write or block write
operations.
Table 34. REGISTER 14H, MANUFACTURER’S TEST REGISTER 1 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
Manufacturer’s Test 1
R/W
Description
This register is used by the manufacturer for test purposes. It should not be read
from or written to in normal operation.
Table 35. REGISTER 15H, MANUFACTURER’S TEST REGISTER 2 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
Manufacturer’s Test 2
R/W
Description
This register is used by the manufacturer for test purposes. It should not be read
from or written to in normal operation.
Table 36. REGISTER 16H, MANUFACTURER’S ID (POWER-ON DEFAULT, 041H)
Bit
Name
R/W
7–0
Manufacturer ID Code
R/W
Description
This register contains the manufacturer’s ID code.
Table 37. REGISTER 17H, REVISION REGISTER (POWER-ON DEFAULT, 4XH)
Bit
Name
R/W
Description
3–0
Minor Revision Code
R
This nibble contains the manufacturer’s code for minor revisions to the device.
Rev 1 = 0h, Rev 2 = 1h, and so on.
7–4
Major Revision Code
R
This nibble denotes the generation of the device. For the ADM1026, this nibble
reads 4h.
Table 38. REGISTER 18H, MASK REGISTER 1 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
0
Ext1 Temp Mask = 0
R/W
When this bit is set, interrupts generated on the Ext1 temperature channel are
masked out.
Description
1
Ext2 Temp
R/W
When this bit is set, interrupts generated on the Ext2/AIN9 channel are masked out.
2
3.3 V STBY Mask = 0
R/W
When this bit is set, interrupts generated on the 3.3 V STBY voltage channel are
masked out.
3
3.3 V MAIN Mask = 0
R/W
When this bit is set, interrupts generated on the 3.3 V MAIN voltage channel are
masked out.
4
+5.0 V Mask = 0
R/W
When this bit is set, interrupts generated on the +5.0 V voltage channel are masked
out.
5
VCCP Mask = 0
R/W
When this bit is set, interrupts generated on the VCCP voltage channel are masked out.
6
+12 V Mask = 0
R/W
When this bit is set, interrupts generated on the +12 V voltage channel are masked out.
7
−12 V Mask = 0
R/W
When this bit is set, interrupts generated on the −12 V voltage channel are masked out.
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ADM1026
Table 39. REGISTER 19H, MASK REGISTER 2 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
Description
0
AIN0 Mask = 0
R/W
When this bit is set, interrupts generated on the AIN0 voltage channel are masked out.
1
AIN1 Mask = 0
R/W
When this bit is set, interrupts generated on the AIN1 voltage channel are masked out.
2
AIN2 Mask = 0
R/W
When this bit is set, interrupts generated on the AIN2 voltage channel are masked out.
3
AIN3 Mask = 0
R/W
When this bit is set, interrupts generated on the AIN3 voltage channel are masked out.
4
AIN4 Mask = 0
R/W
When this bit is set, interrupts generated on the AIN4 voltage channel are masked out.
5
AIN5 Mask = 0
R/W
When this bit is set, interrupts generated on the AIN5 voltage channel are masked out.
6
AIN6 Mask = 0
R/W
When this bit is set, interrupts generated on the AIN6 voltage channel are masked out.
7
AIN7 Mask = 0
R/W
When this bit is set, interrupts generated on the AIN7 voltage channel are masked out.
Table 40. REGISTER 1AH, MASK REGISTER 3 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
Description
0
FAN0 Mask = 0
R/W
When this bit is set, interrupts generated on the FAN0 tach channel are masked out.
1
FAN1 Mask = 0
R/W
When this bit is set, interrupts generated on the FAN1 tach channel are masked out.
2
FAN2 Mask = 0
R/W
When this bit is set, interrupts generated on the FAN2 tach channel are masked out.
3
FAN3 Mask = 0
R/W
When this bit is set, interrupts generated on the FAN3 tach channel are masked out.
4
FAN4 Mask = 0
R/W
When this bit is set, interrupts generated on the FAN4 tach channel are masked out.
5
FAN5 Mask = 0
R/W
When this bit is set, interrupts generated on the FAN5 tach channel are masked out.
6
FAN6 Mask = 0
R/W
When this bit is set, interrupts generated on the FAN6 tach channel are masked out.
7
FAN7 Mask = 0
R/W
When this bit is set, interrupts generated on the FAN7 tach channel are masked out.
Table 41. REGISTER 1BH, MASK REGISTER 4 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
Description
0
Int Temp Mask = 0
R/W
When this bit is set, interrupts generated on the internal temperature channel are
masked out.
1
VBAT Mask = 0
R/W
When this bit is set, interrupts generated on the VBAT voltage channel are masked out.
2
AIN8 Mask = 0
R/W
When this bit is set, interrupts generated on the AIN8 voltage channel are masked out.
3
THERM Mask = 0
R/W
When this bit is set, interrupts generated from THERM events are masked out.
4
AFC Mask = 0
R/W
When this bit is set, interrupts generated from automatic fan control events are
masked out.
5
Unused
R/W
Unused. Reads back 0.
6
CI Mask = 0
R/W
When this bit is set, interrupts generated by the chassis intrusion input are masked out.
7
GPIO16 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO16 channel are masked out.
Table 42. REGISTER 1CH, MASK REGISTER 5 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
0
GPIO0 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO0 channel are masked out.
Description
1
GPIO1 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO1 channel are masked out.
2
GPIO2 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO2 channel are masked out.
3
GPIO3 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO3 channel are masked out.
4
GPIO4 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO4 channel are masked out.
5
GPIO5 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO5 channel are masked out.
6
GPIO6 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO6 channel are masked out.
7
GPIO7 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO7 channel are masked out.
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ADM1026
Table 43. REGISTER 1DH, MASK REGISTER 6 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
0
GPIO8 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO8 channel are masked out.
Description
1
GPIO9 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO9 channel are masked out.
2
GPIO10 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO10 channel are masked out.
3
GPIO11Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO11 channel are masked out.
4
GPIO12 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO12 channel are masked out.
5
GPIO13 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO13 channel are masked out.
6
GPIO14 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO14 channel are masked out.
7
GPIO15 Mask = 0
R/W
When this bit is set, interrupts generated on the GPIO15 channel are masked out.
Table 44. REGISTER 1EH, INT TEMP OFFSET (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
Description
7–0
Int Temp Offset
R/W
This register contains the offset value for the internal temperature channel, a twos
complement result before it is stored or compared to limits. In this way, a sort of
one-point calibration can be done whereby the whole transfer function of the channel
can be moved up or down. From a software point of view, this may be a very simple
method to vary the characteristics of the measurement channel if the thermal
characteristics change for any reason (for instance from one chassis to another), if
the measurement point is moved, if a plug-in card is inserted or removed, and so on.
Table 45. REGISTER 1FH, INT TEMP MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
Int Temp Value
R
Description
This register contains the measured value of the internal temperature channel.
Table 46. REGISTER 20H, STATUS REGISTER 1 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
Description
0
Ext1 Temp Status = 0
R
1, if Ext1 value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise. This bit is set (once only) if a THERM mode is
engaged as a result of Ext1 temp readings exceeding the Ext1 THERM limit. This bit
is also set (once only) if THERM mode is disengaged as a result of Ext1 temperature
readings going 5C below Ext1 THERM limit.
1
Ext2 Temp Status = 0
R
1, if Ext 2 value (or AIN9 if in voltage measurement mode) is above the /AIN9 status =
0 high limit or below the low limit on the previous conversion cycle; 0 otherwise. This
bit is set (once only) if a THERM mode is engaged as a result of Ext2 temperature
readings exceeding the Ext2 THERM limit. This bit is also set (once only) if THERM
mode is disengaged as a result of Ext2 temperature readings going 5C below Ext2
THERM limit.
2
3.3 V STBY Status = 0
R
1, if 3.3 V STBY value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
3
3.3 V MAIN Status = 0
R
1, if 3.3 V MAIN value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
4
+5.0 V Status = 0
R
1, if +5.0 V value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
5
VCCP Status = 0
R
1, if VCCP value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
6
+12 V Status = 0
R
1, if +12 V value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
7
−12 V Status = 0
R
1, if -12 V value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
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ADM1026
Table 47. REGISTER 21H, STATUS REGISTER 2 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
0
AIN0 Status = 0
R
1, if AIN0 to AIN7 value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
Description
1
AIN1 Status = 0
R
1, if AIN0 to AIN7 value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
2
AIN2 Status = 0
R
1, if AIN0 to AIN7 value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
3
AIN3 Status = 0
R
1, if AIN0 to AIN7 value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
4
AIN4 Status = 0
R
1, if AIN0 to AIN7 value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
5
AIN5 Status = 0
R
1, if AIN0 to AIN7 value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
6
AIN6 Status = 0
R
1, if AIN0 to AIN7 value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
7
AIN7 Status = 0
R
1, if AIN0 to AIN7 value is above the high limit or below the low limit on the previous
conversion cycle; 0 otherwise.
Table 48. REGISTER 22H, STATUS REGISTER 3 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
0
FAN0 Status 1 = 0
R
1, if FAN0 to FAN7 value is above the high limit on the previous conversion cycle;
0 otherwise.
Description
1
FAN1 Status 1 = 0
R
1, if FAN0 to FAN7 value is above the high limit on the previous conversion cycle;
0 otherwise.
2
FAN2 Status 1 = 0
R
1, if FAN0 to FAN7 value is above the high limit on the previous conversion cycle;
0 otherwise.
3
FAN3 Status 1 = 0
R
1, if FAN0 to FAN7 value is above the high limit on the previous conversion cycle;
0 otherwise.
4
FAN4 Status 1 = 0
R
1, if FAN0 to FAN7 value is above the high limit on the previous conversion cycle;
0 otherwise.
5
FAN5 Status 1 = 0
R
1, if FAN0 to FAN7 value is above the high limit on the previous conversion cycle;
0 otherwise.
6
FAN6 Status 1 = 0
R
1, if FAN0 to FAN7 value is above the high limit on the previous conversion cycle;
0 otherwise.
7
FAN7 Status 1 = 0
R
1, if FAN0 to FAN7 value is above the high limit on the previous conversion cycle;
0 otherwise.
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Table 49. REGISTER 23H, STATUS REGISTER 4 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
0
INT Temp Status = 0
R
1, if INT value is above the high limit or below the low limit on the previous
conversion cycle, 0 otherwise. This bit is set (once only) if a THERM mode is
engaged as a result of INT temperature readings exceeding the INT THERM limit.
This bit is also set (once only) if THERM mode is disengaged as a result of internal
temperature readings going 5C below Int THERM limit.
1
VBAT Status = 0
R
1, if VBAT value is above the high limit or below the low limit on the previous
conversion cycle, 0 otherwise.
2
AIN8 Status = 0
R
1, if AIN8 value is above the high limit or below the low limit on the previous
conversion cycle, 0 otherwise.
3
THERM Status = 0
R
This bit is set (once only) if a THERM mode is engaged as a result of temperature
readings exceeding the THERM limits on any channel. This bit is also set (once
only) if THERM mode is disengaged as a result of temperature readings going 5C
below THERM limits on any channel.
4
AFC Status = 0
R
This bit is set (once only) if the fan turns on when in automatic fan speed control (AFC)
mode as a result of a temperature reading exceeding TMIN on any channel. This bit is
also set (once only) if the fan turns off when in automatic fan speed control mode.
5
Unused
R
Unused. Reads back 0.
6
CI Status = 0
R
This bit latches a chassis intrusion event.
7
GPIO16 Status = 0
R
When GPIO16 is configured as an input, this bit is set when GPIO16 is asserted.
(Asserted may be active high or active low depending on the setting in GPIO
configuration register.)
When GPIO16 is configured as an output, setting this bit asserts GPIO16. (Asserted
may be active high or active low depending on setting in GPIO configuration register.)
R/W
Description
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Table 50. REGISTER 24H, STATUS REGISTER 5 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
(Note 1)
0
GPIO0 Status = 0
R
R/W
1
GPIO1 Status = 0
R
R/W
2
GPIO2 Status = 0
R
R/W
3
GPIO3 Status = 0
R
R/W
4
GPIO4 Status = 0
R
R/W
5
GPIO5 Status = 0
R
R/W
6
GPIO6 Status = 0
R
R/W
7
GPIO7 Status = 0
R
R/W
Description
When GPIO0 is configured as an input, this bit is set when GPIO0 is asserted.
(Asserted may be active high or active low depending on setting of Bit 1 in GPIO
Configuration Register 1.)
When GPIO0 is configured as an output, setting this bit asserts GPIO0. (Asserted
may be active high or active low depending on setting of Bit 1 in GPIO Configuration
Register 1.)
When GPIO1 is configured as an input, this bit is set when GPIO1 is asserted.
(Asserted may be active high or active low depending on setting of Bit 3 in GPIO
Configuration Register 1.)
When GPIO1 is configured as an output, setting this bit asserts GPIO1. (Asserted
may be active high or active low depending on setting of Bit 3 in GPIO Configuration
Register 1.)
When GPIO2 is configured as an input, this bit is set when GPIO2 is asserted.
(Asserted may be active high or active low depending on setting of Bit 5 in GPIO
Configuration Register 1.)
When GPIO2 is configured as an output, setting this bit asserts GPIO2. (Asserted
may be active high or active low depending on setting of Bit 5 in GPIO Configuration
Register 1.)
When GPIO3 is configured as an input, this bit is set when GPIO3 is asserted.
(Asserted may be active high or active low depending on setting of Bit 7 in GPIO
Configuration Register 1.)
When GPIO3 is configured as an output, setting this bit asserts GPIO3. (Asserted
may be active high or active low depending on setting of Bit 7 in GPIO Configuration
Register 1.)
When GPIO4 is configured as an input, this bit is set when GPIO4 is asserted.
(Asserted may be active high or active low depending on setting of Bit 1 in GPIO
Configuration Register 2.)
When GPIO4 is configured as an output, setting this bit asserts GPIO4. (Asserted
may be active high or active low depending on setting of Bit 1 in GPIO Configuration
Register 2.)
When GPIO5 is configured as an input, this bit is set when GPIO5 is asserted.
(Asserted may be active high or active low depending on setting of Bit 3 in GPIO
Configuration Register 2.)
When GPIO5 is configured as an output, setting this bit asserts GPIO5. (Asserted
may be active high or active low depending on setting of Bit 3 in GPIO Configuration
Register 2.)
When GPIO6 is configured as an input, this bit is set when GPIO6 is asserted.
(Asserted may be active high or active low depending on setting of Bit 5 in GPIO
Configuration Register 2.)
When GPIO6 is configured as an output, setting this bit asserts GPIO6. (Asserted
may be active high or active low depending on setting of Bit 5 in GPIO Configuration
Register 2.)
When GPIO7 is configured as an input, this bit is set when GPIO7 is asserted.
(Asserted may be active high or active low depending on setting of Bit 7 in GPIO
Configuration Register 2.)
When GPIO7 is configured as an output, setting this bit asserts GPIO7. (Asserted
may be active high or active low depending on setting of Bit 7 in GPIO Configuration
Register 2.)
1. GPIO status bits can be written only when a GPIO pin is configured as output. Read-only otherwise.
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Table 51. REGISTER 25H, STATUS REGISTER 6 (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
(Note 1)
0
GPIO8 Status = 0
R
R/W
1
GPIO9 Status = 0
R
R/W
2
GPIO10 Status = 0
R
R/W
3
GPIO11 Status = 0
R
R/W
4
GPIO12 Status = 0
R
R/W
5
GPIO13 Status = 0
R
R/W
6
GPIO14 Status = 0
R
R/W
7
GPIO15 Status = 0
R
R/W
Description
When GPIO8 is configured as an input, this bit is set when GPIO8 is asserted.
(Asserted may be active high or active low depending on setting of Bit 1 in GPIO
Configuration Register 3.)
When GPIO8 is configured as an output, setting this bit asserts GPIO8. (Asserted
may be active high or active low depending on setting of Bit 1 in GPIO Configuration
Register 3.)
When GPIO9 is configured as an input, this bit is set when GPIO9 is asserted.
(Asserted may be active high or active low depending on setting of Bit 3 in GPIO
Configuration Register 3.)
When GPIO9 is configured as an output, setting this bit asserts GPIO9. (Asserted
may be active high or active low depending on setting of Bit 3 in GPIO Configuration
Register 3.)
When GPIO10 is configured as an input, this bit is set when GPIO10 is asserted.
(Asserted may be active high or active low depending on setting of Bit 5 in GPIO
Configuration Register 3.)
When GPIO10 is configured as an output, setting this bit asserts GPIO10. (Asserted
may be active high or active low depending on setting of Bit 5 in GPIO Configuration
Register 3.)
When GPIO11 is configured as an input, this bit is set when GPIO11 is asserted.
(Asserted may be active high or active low depending on setting of Bit 7 in GPIO
Configuration Register 3.)
When GPIO11 is configured as an output, setting this bit asserts GPIO11. (Asserted
may be active high or active low depending on setting of Bit 7 in GPIO Configuration
Register 3.)
When GPIO12 is configured as an input, this bit is set when GPIO12 is asserted.
(Asserted may be active high or active low depending on setting of Bit 1 in GPIO
Configuration Register 4.)
When GPIO12 is configured as an output, setting this bit asserts GPIO12. (Asserted
may be active high or active low depending on setting of Bit 1 in GPIO Configuration
Register 4.)
When GPIO13 is configured as an input , this bit is set when GPIO13 is asserted.
(Asserted may be active high or active low depending on setting of Bit 3 in GPIO
Configuration Register 4.)
When GPIO13 is configured as an output, setting this bit asserts GPIO13. (Asserted
may be active high or active low depending on setting of Bit 3 in GPIO Configuration
Register 4.)
When GPIO14 is configured as an input , this bit is set when GPIO14 is asserted.
(Asserted may be active high or active low depending on setting of Bit 5 in GPIO
Configuration Register 4.)
When GPIO14 is configured as an output, setting this bit asserts GPIO14. (Asserted
may be active high or active low depending on setting of Bit 5 in GPIO Configuration
Register 4.)
When GPIO15 is configured as an input, this bit is set when GPIO15 is asserted.
(Asserted may be active high or active low depending on setting of Bit 7 in GPIO
Configuration Register 4.)
When GPIO15 is configured as an output, setting this bit asserts GPIO15. (Asserted
may be active high or active low depending on setting of Bit 7 in GPIO Configuration
Register 4.)
1. GPIO status bits can be written only when a GPIO pin is configured as output. Read-only otherwise.
Table 52. REGISTER 26H, VBAT MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
VBAT Value
R
Description
This register contains the measured value of the VBAT analog input channel.
Table 53. REGISTER 27H, AIN8 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
AIN8 Value
R
Description
This register contains the measured value of the AIN8 analog input channel.
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Table 54. REGISTER 28H, EXT1 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
Ext1 Value
R
Description
This register contains the measured value of the Ext1 Temp channel.
Table 55. REGISTER 29H, EXT2/AIN9 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
Description
7–0
Ext2 Temp/
AIN9 Low Limit
R
This register contains the measured value of the Ext2 Temp/AIN9 channel depending
on which bit is configured.
Table 56. REGISTER 2AH, 3.3 V STBY MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
3.3 V STBY Value
R
Description
This register contains the measured value of the 3.3 V STBY voltage.
Table 57. REGISTER 2BH, 3.3 V MAIN MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
3.3 V MAIN Value
R
Description
This register contains the measured value of the 3.3 V MAIN voltage.
Table 58. REGISTER 2CH, +5.0 V MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
+5.0 V Value
R
Description
This register contains the measured value of the +5.0 V analog input channel.
Table 59. REGISTER 2DH, VCCP MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
VCCP Value
R
Description
This register contains the measured value of the VCCP analog input channel.
Table 60. REGISTER 2EH, +12 V MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
+12 V Value
R
Description
This register contains the measured value of the +12 V analog input channel.
Table 61. REGISTER 2FH, −12 V MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
–12 V Value
R
Description
This register contains the measured value of the -12 V analog input channel.
Table 62. REGISTER 30H, AIN0 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
AIN0 Value
R
Description
This register contains the measured value of the AIN0 analog input channel.
Table 63. REGISTER 31H, AIN1 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
AIN1 Value
R
Description
This register contains the measured value of the AIN1 analog input channel.
Table 64. REGISTER 32H, AIN2 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
AIN2 Value
R
Description
This register contains the measured value of the AIN2 analog input channel.
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Table 65. REGISTER 33H, AIN3 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
AIN3 Value
R
Description
This register contains the measured value of the AIN3 analog input channel.
Table 66. REGISTER 34H, AIN4 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
AIN4 Value
R
Description
This register contains the measured value of the AIN4 analog input channel.
Table 67. REGISTER 35H, AIN5 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
AIN5 Value
R
Description
This register contains the measured value of the AIN5 analog input channel.
Table 68. REGISTER 36H, AIN6 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
AIN6 Value
R
Description
This register contains the measured value of the AIN6 analog input channel.
Table 69. REGISTER 37H, AIN7 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
AIN7 Value
R
Description
This register contains the measured value of the AIN7 analog input channel.
Table 70. REGISTER 38H, FAN0 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
FAN0 Value
R
Description
This register contains the measured value of the FAN0 tach input channel.
Table 71. REGISTER 39H, FAN1 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
FAN1 Value
R
Description
This register contains the measured value of the FAN1 tach input channel.
Table 72. REGISTER 3AH, FAN2 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
FAN2 Value
R
Description
This register contains the measured value of the FAN2 tach input channel.
Table 73. REGISTER 3BH, FAN3 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
FAN3 Value
R
Description
This register contains the measured value of the FAN3 tach input channel.
Table 74. REGISTER 3CH, FAN4 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
FAN4 Value
R
Description
This register contains the measured value of the FAN4 tach input channel.
Table 75. REGISTER 3DH, FAN5 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
FAN5 Value
R
Description
This register contains the measured value of the FAN5 tach input channel.
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Table 76. REGISTER 3EH, FAN6 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
FAN6 Value
R
Description
This register contains the measured value of the FAN6 tach input channel.
Table 77. REGISTER 3FH, FAN7 MEASURED VALUE (POWER-ON DEFAULT, 00H)
Bit
Name
R/W
7–0
FAN7 Value
R
Description
This register contains the measured value of the FAN7 tach input channel.
Table 78. REGISTER 40H, EXT1 HIGH LIMIT (POWER-ON DEFAULT 64H/1005C)
Bit
Name
R/W
7–0
Ext1 High Limit
R/W
Description
This register contains the high limit of the Ext1 Temp channel.
Table 79. REGISTER 41H, EXT2/AIN9 HIGH LIMIT (POWER-ON DEFAULT 64H/1005C)
Bit
Name
R/W
7–0
Ext2 Temp/
AIN9 High Limit
R/W
Description
This register contains the high limit of the Ext2 Temp/AIN9 channel depending on
which one is configured.
Table 80. REGISTER 42H, 3.3 V STBY HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
3.3 V STBY High Limit
R/W
Description
This register contains the high limit of the 3.3 V STBY analog input channel.
Table 81. REGISTER 43H, 3.3 V MAIN HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
3.3 V MAIN High Limit
R/W
Description
This register contains the high limit of the 3.3 V MAIN analog input channel.
Table 82. REGISTER 44H, +5.0 V HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
+5.0 V High Limit
R/W
Description
This register contains the high limit of the +5.0 V analog input channel.
Table 83. REGISTER 45H, VCCP HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
VCCP High Limit
R/W
Description
This register contains the high limit of the VCCP analog input channel.
Table 84. REGISTER 46H, +12 V HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
+12 V High Limit
R/W
Description
This register contains the high limit of the +12 V analog input channel.
Table 85. REGISTER 47H, −12 V HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
−12 V High Limit
R/W
Description
This register contains the high limit of the -12 V analog input channel.
Table 86. REGISTER 48H, EXT1 LOW LIMIT (POWER-ON DEFAULT 80H)
Bit
Name
R/W
7–0
Ext1 Low Limit
R/W
Description
This register contains the low limit of the Ext1 Temp channel.
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Table 87. REGISTER 49H, EXT/AIN9 LOW LIMIT (POWER-ON DEFAULT 80H)
Bit
Name
R/W
7–0
Ext2 Temp /AIN9 Low
Limit
R/W
Description
This register contains the low limit of the Ext2 Temp/AIN9 channel depending on
which bit is configured.
Table 88. REGISTER 4AH, 3.3 V STBY LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
3.3 V STBY Low Limit
R/W
Description
This register contains the low limit of the 3.3 V STBY analog input channel.
Table 89. REGISTER 4BH, 3.3 V MAIN LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
3.3 V MAIN Low Limit
R/W
Description
This register contains the low limit of the 3.3 V MAIN analog input channel.
Table 90. REGISTER 4CH, +5.0 V LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
+5.0 V Low Limit
R/W
Description
This register contains the low limit of the +5.0 V analog input channel.
Table 91. REGISTER 4DH, VCCP LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
VCCP Low Limit
R/W
Description
This register contains the low limit of the VCCP analog input channel.
Table 92. REGISTER 4EH, +12 V LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
+12 V Low Limit
R/W
Description
This register contains the low limit of the +12 V analog input channel.
Table 93. REGISTER 4FH, −12 V LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
−12 V Low Limit
R/W
Description
This register contains the low limit of the -12 V analog input channel.
Table 94. REGISTER 50H, AIN0 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
AIN0 High Limit
R/W
Description
This register contains the high limit of the AIN0 analog input channel.
Table 95. REGISTER 51H, AIN1 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
AIN1 High Limit
R/W
Description
This register contains the high limit of the AIN1 analog input channel.
Table 96. REGISTER 52H, AIN2 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
AIN2 High Limit
R/W
Description
This register contains the high limit of the AIN2 analog input channel.
Table 97. REGISTER 53H, AIN3 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
AIN3 High Limit
R/W
Description
This register contains the high limit of the AIN3 analog input channel.
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Table 98. REGISTER 54H, AIN4 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
AIN4 High Limit
R/W
Description
This register contains the high limit of the AIN4 analog input channel.
Table 99. REGISTER 55H, AIN5 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
AIN5 High Limit
R/W
Description
This register contains the high limit of the AIN5 analog input channel.
Table 100. REGISTER 56H, AIN6 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
AIN6 High Limit
R/W
Description
This register contains the high limit of the AIN6 analog input channel.
Table 101. REGISTER 57H, AIN7 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
AIN7 High Limit
R/W
Description
This register contains the high limit of the AIN7 analog input channel.
Table 102. REGISTER 58H, AIN0 LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
AIN0 Low Limit
R/W
Description
This register contains the low limit of the AIN0 analog input channel.
Table 103. REGISTER 59H, AIN1 LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
AIN1 Low Limit
R/W
Description
This register contains the low limit of the AIN1 analog input channel.
Table 104. REGISTER 5AH, AIN2 LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
AIN2 Low Limit
R/W
Description
This register contains the low limit of the AIN2 analog input channel.
Table 105. REGISTER 5BH, AIN3 LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
AIN3 Low Limit
R/W
Description
This register contains the low limit of the AIN3 analog input channel.
Table 106. REGISTER 5CH, AIN4 LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
AIN4 Low Limit
R/W
Description
This register contains the low limit of the AIN4 analog input channel.
Table 107. REGISTER 5DH, AIN5 LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
AIN5 Low Limit
R/W
Description
This register contains the low limit of the AIN5 analog input channel.
Table 108. REGISTER 5EH, AIN6 LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
AIN6 Low Limit
R/W
Description
This register contains the low limit of the AIN6 analog input channel.
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Table 109. REGISTER 5FH, AIN7 LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
AIN7 Low Limit
R/W
Description
This register contains the low limit of the AIN7 analog input channel.
Table 110. REGISTER 60H, FAN0 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
FAN0 High Limit
R/W
Description
This register contains the high limit of the FAN0 tach channel.
Table 111. REGISTER 61H, FAN1 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
FAN1 High Limit
R/W
Description
This register contains the high limit of the FAN1 tach channel.
Table 112. REGISTER 62H, FAN2 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
FAN2 High Limit
R/W
Description
This register contains the high limit of the FAN2 tach channel.
Table 113. REGISTER 63H, FAN3 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
FAN3 High Limit
R/W
Description
This register contains the high limit of the FAN3 tach channel.
Table 114. REGISTER 64H, FAN4 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
FAN4 High Limit
R/W
Description
This register contains the high limit of the FAN4 tach channel.
Table 115. REGISTER 65H, FAN5 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
FAN5 High Limit
R/W
Description
This register contains the high limit of the FAN5 tach channel.
Table 116. REGISTER 66H, FAN6 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
FAN6 High Limit
R/W
Description
This register contains the high limit of the FAN6 tach channel.
Table 117. REGISTER 67H, FAN7 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
FAN7 High Limit
R/W
Description
This register contains the high limit of the FAN7 tach channel.
Table 118. REGISTER 68H, INT TEMP HIGH LIMIT (POWER-ON DEFAULT, 50H 805C)
Bit
Name
R/W
7–0
Int Temp High Limit
R/W
Description
This register contains the high limit of the internal temperature channel.
Table 119. REGISTER 69H, INT TEMP HIGH LIMIT (POWER-ON DEFAULT 80H)
Bit
Name
R/W
7–0
Int Temp Low Limit
R/W
Description
This register contains the low limit of the internal temperature channel.
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Table 120. REGISTER 6AH, VBAT HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
VBAT High Limit
R/W
Description
This register contains the high limit of the VBAT analog input channel.
Table 121. REGISTER 6BH, VBAT LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
VBAT Low Limit
R/W
Description
This register contains the low limit of the VBAT analog input channel.
Table 122. REGISTER 6CH, AIN8 HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
Name
R/W
7–0
AIN8 High Limit
R/W
Description
This register contains the high limit of the AIN8 analog input channel.
Table 123. REGISTER 6DH, AIN8 LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
Name
R/W
7–0
AIN8 Low Limit
R/W
Description
This register contains the low limit of the AIN8 analog input channel.
Table 124. REGISTER 6EH, EXT1 TEMP OFFSET (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
7–0
Ext1 Temp Offset
R/W
This register contains the offset value for the external 1 temperature channel. A twos
complement number can be written to this register, which is then added to the
measured result before it is stored or compared to limits. In this way, a sort of
one-point calibration can be done whereby the whole transfer function of the channel
can be moved up or down. From a software point of view, this may be a very simple
method to vary the characteristics of the measurement channel if the thermal
characteristics change for any reason (for instance from one chassis to another), if the
measurement point is moved, if a plug-in card is inserted or removed, and so on.
Table 125. REGISTER 6FH, EXT2 TEMP OFFSET (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
7–0
Ext2 Temp Offset
R/W
This register contains the offset value for the external 2 temperature channel. A twos
complement number can be written to this register, which is then added to the
measured result before it is stored or compared to limits. In this way, a sort of
one-point calibration can be done whereby the whole transfer function of the channel
can be moved up or down. From a software point of view, this may be a very simple
method to vary the characteristics of the measurement channel if the thermal
characteristics change for any reason (for instance from one chassis to another), if the
measurement point is moved, if a plug-in card is inserted or removed, and so on.
Table 126. ORDERING INFORMATION
Device Order Number
Temperature Range
Package Type
Package Option
Shipping†
ADM1026JSTZ−REEL
0C to +100C
48−Lead LQFP
(Pb−Free)
ST−48
2,000 Tape & Reel
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
*The “Z’’ suffix indicates Pb−Free part.
http://onsemi.com
54
ADM1026
PACKAGE DIMENSIONS
48 LEAD LQFP, 7x7, 0.5P
CASE 932AA−01
ISSUE A
4X
0.2 Y T-U Z
D
PIN 1
CORNER
D/2
Z
48
e/2
DETAIL K
37
1
36
T
U
G
E
G
E1
E/2
E1/2
12
T, U, Z
25
DETAIL K
NOTE 9
13
24
D1/2
D1
4X
BASE METAL
0.2 H T-U Z
0.08 Y
e/2
44 X
48 X
e
ÇÇÇÇ
ÉÉÉ
ÇÇÇÇ
ÉÉÉ
ÇÇÇÇ
ÉÉÉ
PLATING
DETAIL F
H
Y
NOTES:
1. DIMENSIONS ARE IN MILLIMETERS.
2. INTERPRET DIMENSIONS AND TOLERANCES PER
ASME Y14.5M, 1994.
3. DATUM PLANE H IS LOCATED AT BOTTOM OF
LEAD AND IS COINCIDENT WITH THE LEAD
WHERE THE LEAD EXITS THE PLASTIC BODY AT
THE BOTTOM OF THE PARTING LINE.
4. DATUMS T, U, AND Z TO BE DETERMINED AT
DATUM PLANE H.
5. DIMENSIONS D AND E TO BE DETERMINED AT
SEATING PLANE Y.
6. DIMENSIONS D1 AND E1 DO NOT INCLUDE MOLD
PROTRUSION. ALLOWABLE PROTRUSION IS
0.250 PER SIDE. DIMENSIONS D1 AND E1 DO
INCLUDE MOLD MISMATCH AND ARE
DETERMINED AT DATUM PLANE H.
7. DIMENSION b DOES NOT INCLUDE DAMBAR
PROTRUSION. DAMBAR PROTRUSION SHALL
NOT CAUSE THE b DIMENSION TO EXCEED 0.350.
8. MINIMUM SOLDER PLATE THICKNESS SHALL BE
0.0076.
9. EXACT SHAPE OF EACH CORNER IS OPTIONAL.
c1 c
b1
b
b
SEATING
PLANE
0.08
M
Y T-U Z
SECTION G−G
q1
DIM
A
A1
A2
b
b1
c
c1
D
D1
e
E
E1
L
L1
R
S
q
q1
MILLIMETERS
MIN
MAX
1.4
1.6
0.05
0.15
1.35
1.45
0.17
0.27
0.17
0.23
0.09
0.20
0.09
0.16
9.0 BSC
7.0 BSC
0.5 BSC
9.0 BSC
7.0 BSC
0.5
0.7
1.0 REF
0.15
0.25
0.2 REF
1_
5_
12 REF
TOP & BOTTOM
R
A A2
A1
(S)
DETAIL F
L
(L1)
0.250
q
GAUGE PLANE
ON Semiconductor and
are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice
to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability
arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.
“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All
operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights
nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications
intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should
Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates,
and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death
associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal
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PUBLICATION ORDERING INFORMATION
LITERATURE FULFILLMENT:
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http://onsemi.com
55
ON Semiconductor Website: www.onsemi.com
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For additional information, please contact your local
Sales Representative
ADM1026/D
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