Dual PWM Fan Controller and Temperature Monitor for High Availability Systems

ADM1029
Dual PWM Fan Controller
and Temperature Monitor for
High Availability Systems
The ADM1029 is a versatile fan controller and monitor for use in
personal computers, servers, telecommunications equipment, or any
high-availability system where reliable control and monitoring of
multiple cooling fans is required. Each ADM1029 can control the
speed of one or two fans and can measure the speed of fans that have a
tachometer output. The ADM1029 can also measure the temperature
of one or two external sensing diodes or an internal temperature
sensor, allowing fan speed to be adjusted to keep system temperature
within acceptable limits. The ADM1029 has FAULT inputs for use
with fans that can signal failure conditions, and inputs to detect
whether or not fans are connected.
The ADM1029 communicates with the host processor over an
System Management (SMBus) serial bus. It supports eight different
serial bus addresses, so that up to eight devices can be connected to a
common bus, controlling up to sixteen fans. This makes software
support and hardware design scalable.
The ADM1029 has an interrupt output (INT) that allows it to signal
fault conditions to the host processor. It also has a separate, cascadable
fault output (CFAULT) that allows the ADM1029 to signal a fault
condition to other ADM1029s.
The ADM1029 has a number of useful features including an
automatic fan speed control option implemented in hardware with no
software requirement, automatic use of backup fans in the event of fan
failure, and supports hot-swapping of failed fans.



Software Programmable and Automatic Fan Speed Control
Automatic Fan Speed Control Allows Control
Independent of CPU Intervention after Initial Setup
Control Loop Minimizes Acoustic Noise and Power Consumption
Remote and Local Temperature Monitoring
Dual Fan Speed Measurement
Supports Backup and Redundant Fans
Supports Hot Swapping of Fans
Cascadable Fault Output Allows Fault Signaling between Multiple
ADM1029s
Address Pin Allows Up to Eight ADM1029s in A System
Small 24-lead QSOP Package
This is a Pb-Free Device*
 Network Servers and Personal Computers
 Microprocessor-based Office Equipment
 High Availability Telecommunications Equipment
DRIVE1 1
24 DRIVE2
FAULT1 2
23 FAULT2
TACH1 3
22 TACH2
PRESENT1 4
21 PRESENT2
SCL 5
20 AIN1/GPIO1
SDA 6
19 AIN0/GPIO0
GND 7
18 TMIN/INSTALL
VCC 8
17 D2+/GPIO6
CFAULT 9
16 D2−/GPIO5
15 ADD
GPIO2 11
14 D1+/GPIO4
RESET 12
13 D1−/GPIO3
ADM1029
Top View
(Not To Scale)
MARKING DIAGRAM
1029ARQZ
#YYWW
= Special Device Code
= Pb-Free Package
= Date Code
ORDERING INFORMATION
* For additional information on our Pb-Free strategy and soldering details, please
download the ON Semiconductor Soldering and Mounting Techniques
Reference Manual, SOLDERRM/D.
April, 2012 − Rev. 2
PIN ASSIGNMENT
1029ARQZ
#
YYWW
Applications
 Semiconductor Components Industries, LLC, 2012
QSOP 24
CASE 492B
INT 10
Features
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
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

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See detailed ordering and shipping information in the package
dimensions section on page 49 of this data sheet.
Publication Order Number:
ADM1029/D
ADM1029
VCC
8
ADM1029
SERIAL BUS
5 SCL
INTERFACE
6 SDA
ADDRESS POINTER
REGISTER
SLAVE ADDRESS
REGISTER
PRESENT1 4
INTERRUPT MASK
FAN 1 STATUS
REGISTER
FAULT1 2
10 INT
REGISTERS
INTERRUPT
MASKING
INTERRUPT STATUS
9 CFAULT
REGISTERS
FAN 1 MIN
SPEED REGISTER
DRIVE1 1
PWM
FAN 1 ALARM
CONTROLLER
SPEED REGISTER
LIMIT CAMPARATOR
FAN 1 HOT-PLUG
12 RESET
VALUE AND LIMIT
SPEED REGISTER
REGISTERS
11 GPIO2
TACH1 3
FAN SPEED
TACH2 22
COUNTER
PRESENT2 21
G.P. I/O REGISTER
FAN 2 STATUS
20 AIN1/GPIO1
REGISTER
19 AIN0/GPIO0
FAN 2 MIN
FAULT2 23
17 D2+/GPIO6
SPEED REGISTER
ADC
DRIVE2 24
PWM
FAN 2 ALARM
CONTROLLER
SPEED REGISTER
ANALOG
REMOTE SENSOR
MUX
FAN 2 HOT-PLUG
BANDGAP
SPEED REGISTER
REFERENCE
16 D2−/GPIO5
SIGNAL
14 D1+/GPIO4
CONDITIONING
13 D1−/GPIO3
18 TMIN/INSTALL
BANDGAP
TEMP SENSOR
15 ADD
7
GND
Figure 1. Functional Block Diagram
Table 1. ABSOLUTE MAXIMUM RATINGS
Rating
Value
Unit
6.5
V
−0.3 to (VCC + 0.3)
V
−0.3 to +6.5
V
5
mA
Package Input Current
20
mA
Maximum Junction Temperature (TJ max)
150
C
−65 to + 150
C
Positive Supply Voltage (VCC)
Voltage on Pins 13–18
Voltage on Any Other Input or Output Pin
Input Current at Any Pin
Storage Temperature Range
Lead Temperature
Vapor Phase (60 sec)
Infrared (15 sec)
C
215
200
ESD Rating All Pins
2,000
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.
Table 2. THERMAL CHARACTERISTICS
Package Type
24-lead QSOP
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2
qJA
qJC
Unit
105
39
C/W
ADM1029
Table 3. PIN FUNCTION DESCRIPTIONS
Pin No.
Mnemonic
1
DRIVE1
Open Drain Digital Output. Pulsewidth Modulated (PWM) output to control the speed of Fan 1.
Requires 10 kW typical pull-up resistor.
Description
2
FAULT1
Open Drain Digital I/O. When used with a fan having a fault output, a Logic 0 input to this pin signals a
fault on Fan 1. Also used as a fault output.
3
TACH1
Open Drain Digital Input. Digital fan tachometer input for Fan 1. Will accept logic signals up to 5 V even
when VCC is lower than 5 V.
4
PRESENT1
5
SCL
Open Drain Digital Input. Serial Bus Clock. Requires 2.2 kW pull-up typical.
6
SDA
Digital I/O. Serial Bus bidirectional data. Open-drain output requires 2.2 kW pull-up.
7
GND
System Ground
8
VCC
Power (3.0 V to 5.5 V). Typically powered from 3.3 V power rail. Bypass with the parallel combination of
10 mF (electrolytic or tantalum) and 0.1 mF (ceramic) bypass capacitors.
Open Drain Digital I/O. Cascade fault input/output used for fault signaling between multiple ADM1029s.
Open Drain Digital Input. A shorting link in the fan connector holds this pin low when Fan 1 is
connected.
9
CFAULT
10
INT
11
GPIO2
Open Drain Digital I/O. General-purpose logic I/O pin.
12
RESET
Open Drain Digital Input. Active low reset input.
13
D1−/GPIO3
Analog Input/Open Drain Digital I/O. Connected to cathode of external temperature-sensing diode, or
may be reconfigured as a general-purpose logic input/output.
14
D1+/GPIO4
Analog Input/Open Drain Digital I/O. Connected to anode of external temperature-sensing diode, or
may be reconfigured as a general-purpose logic input/output.
15
ADD
16
D2−/GPIO5
Analog Input/Open Drain Digital I/O. Connected to cathode of external temperature-sensing diode, or
may be reconfigured as a general-purpose logic input/output.
17
D2+/GPIO6
Analog Input/Open Drain Digital I/O. Connected to anode of external temperature-sensing diode, or
may be reconfigured as a general-purpose logic input/output.
18
TMIN/INSTALL
Eight-level Analog Input. The voltage on this pin defines whether automatic fan speed control is
enabled, the minimum temperature at which the fan(s) will turn on in automatic speed control mode,
and the number of fans that should be installed.
19
AIN0/GPIO0
Analog Input/Open Drain Digital I/O. May be configured as a 0 V to 2.5 V analog input or as a
general-purpose digital I/O pin.
20
AIN1/GPIO1
Analog Input/Open Drain Digital I/O. May be configured as a 0 V to 2.5 V analog input or as a
general-purpose digital I/O pin.
21
PRESENT2
Open Drain Digital Input. A shorting link in the fan connector holds this pin low when Fan 2 is
connected.
22
TACH2
Open Drain Digital Input. Digital fan tachometer input for Fan 2. Will accept logic signals up to 5 V even
when VCC is lower than 5 V.
23
FAULT2
Open Drain Digital I/O. When used with a fan having a fault output, a Logic 0 input to this pin signals a
fault on Fan 2. Also used as a fault output.
24
DRIVE2
Open Drain Digital Output. Pulsewidth Modulated (PWM) output to control the speed of Fan 2.
Requires 10 kW typical pull-up resistor.
Digital Output. Interrupt Request (Open Drain). The output is enabled when Bit 1 of the Configuration
Register is set to 0. The default state is enabled.
Eight-level Analog Input. Used to set the three LSBs of the serial bus address.
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ADM1029
Table 4. ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VCC = VMIN to VMAX, unless otherwise noted. (Note 1 and 2))
Parameter
Test Conditions/Comments
Min
Typ
Max
Unit
3.0
3.3
5.5
V
−
−
−
1.7
1.5
10
3.0
−
60
mA
mA
mA
Internal Sensor Accuracy
−
1.0
3.0
C
Resolution
−
1.0
−
C
−
3.0
5.0
C
−
1.0
−
C
−
−
90
5.5
−
−
mA
Total Unadjusted Error, TUE (Note 3)
−
−
1.0
%
Differential Non-linearity, DNL
−
−
1.0
LSB
Power Supply Sensitivity
−
1.0
−
%/V
Conversion Time
Analog Input or Internal Temperature
External Temperature
−
−
11.6
185.6
−
−
−
−
6
−
−
255
−
−
−
−
8800
4400
2200
1100
−
−
−
−
RPM
56.4
60.0
63.6
kHz
POWER SUPPLY
Supply Voltage, VCC
Supply Current, ICC
Interface Inactive, ADC Active
ADC Inactive, DAC Active
Shutdown Mode
TEMPERATURE-TO-DIGITAL CONVERTER
External Diode Sensor Accuracy
0C < TD < 100C
Resolution
Remote Sensor Source Current
High Level
Low Level
ANALOG-TO-DIGITAL CONVERTER
ms
FAN RPM-TO-DIGITAL CONVERTER
Accuracy
60C  TA  100C: VCC = 3.3 V
Full-scale Count
Fan 1 to Fan 2 Nominal Input RPM (Note 4)
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 DIGITAL OUTPUTS (INT, CFAULT)
Output Low Voltage, VOL
IOUT = −6.0 mA, VCC = 3 V
−
−
0.4
V
High Level Output Current, IOH
VOUT = VCC
−
0.1
1.0
mA
Output Low Voltage, VOL
IOUT = –6.0 mA, VCC = 3 V
−
−
0.4
V
High Level Output Leakage Current, IOH
VOUT = VCC
−
0.1
1.0
mA
Input High Voltage, VIH
2.1
−
−
V
Input Low Voltage, VIL
−
−
0.8
V
Hysteresis
−
500
−
mV
Input High Voltage, VIH
2.1
−
−
V
Input Low Voltage, VIL
−
−
0.8
V
–1.0
−
−
mA
−
−
1.0
mA
−
20
−
pF
10
−
100
kHz
−
50
−
ns
OPEN-DRAIN SERIAL DATA BUS OUTPUT (SDA)
SERIAL BUS DIGITAL INPUTS (SCL, SDA)
DIGITAL INPUT LOGIC LEVELS (RESET, GPIO1−6, FAULT1/2, TACH1/2, PRESENT1/2)
DIGITAL INPUT CURRENT
Input High Current, IIH
VIN = VCC
Input Low Current, IIL
VIN = 0
Input Capacitance, CIN
SERIAL BUS TIMING (Note 5)
Clock Frequency, fSCLK
See Figure 2 for All Parameters.
Glitch Immunity, tSW
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ADM1029
Table 4. ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VCC = VMIN to VMAX, unless otherwise noted. (Note 1 and 2))
Parameter
Test Conditions/Comments
Min
Typ
Max
Unit
Bus Free Time, tBUF
4.7
−
−
ms
Start Setup Time, tSU; STA
4.7
−
−
ms
Start Hold Time, tHD; STA
4.0
−
−
ms
Stop Condition Setup Time, tSU; STO
4.0
−
−
ms
SCL Low Time, tLOW
1.3
−
−
ms
SCL High Time, tHIGH
4.0
−
50
ms
SCL, SDA Rise Time, tR
−
−
1,000
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 (Note 5)
1. All voltages are measured with respect to GND, unless otherwise specified.
2. Typicals are at TA = 25C and represent the most likely parametric norm. Shutdown current typ is measured with VCC = 3.3 V.
3. Total unadjusted error (TUE) includes offset, gain, and linearity errors of the ADC, multiplexer.
4. The total fan count is based on two pulses per revolution of the fan tachometer output.
5. 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.
NOTE: Specifications subject to change without notice.
tF
t LOW
t HD; STA
tR
SCL
t HD; STA
t HIGH
t HD; DAT
t SU; STA
t SU; DAT
t SU; STO
SDA
P
t BUF
S
S
P
Figure 2. Serial Bus Timing Diagram
15
110
100
10
90
5
80
DXP TO GND
READING
REMOTE TEMPERATURE ERROR (C)
TYPICAL PERFORMANCE CHARACTERISTICS
0
DXP TO VCC (3.3 V)
−5
−10
60
50
40
30
20
−15
−20
70
0
3.3
10
30
10
0
100
0
10 20
30 40 50 60
70 80
90 100 110
MEASURED TEMPERATURE
LEAKAGE RESISTANCE (MW)
Figure 3. Remote Temperature Error vs. PC Board
Track Resistance
Figure 4. Pentium) III Temperature Measurement
vs. ADM1029 Reading
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ADM1029
4.5
4.0
REMOTE TEMPERATURE ERROR (C)
REMOTE TEMPERATURE ERROR (C)
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 250 mV p-p
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
VIN = 100 mV p-p
−0.5
−1.0
0
1
4
8
12 16
20 50 100 200 300 400 500 600
1
0
−1
−2
−3
−4
−5
−6
−7
−8
−9
−10
−11
−12
−13
−14
−15
−16
1.0
2.2
FREQUENCY (MHz)
10
10.0
22.0
47.0
80
9
7
6
VCC = 5 V
70
VIN = 100 mV p-p
VIN = 60 mV p-p
VIN = 40 mV p-p
8
5
4
3
2
1
60
50
40
30
VCC = 3.3 V
20
10
0
0
0 0.4 0.8 10 50 100 150 200 250 300 350 400 450 500 550 600
0
1
5
10
25
FREQUENCY (MHz)
50
75
100
250
500
750 1000
SCLK FREQUENCY (kHz)
Figure 7. Remote Temperature Error vs.
Common-mode Noise Frequency
Figure 8. Standby Current vs. Clock Frequency
10
13
LOCAL TEMPERATURE ERROR (C)
REMOTE TEMPERATURE ERROR (C)
4.7
Figure 6. Remote Temperature Error vs.
Capacitance between D+ and D−
SUPPLY CURRENT (mA)
REMOTE TEMPERATURE ERROR (C)
Figure 5. Remote Temperature Error vs. Power
Supply Noise Frequency
−1
3.3
DXP − DXN CAPACITANCE (nF)
12
11
VIN = 40 mV p-p
10
9
8
VIN = 30 mV p-p
VIN = 20 mV p-p
7
6
5
4
3
2
1
0
−1
0
1
4
8 12 16 20 50 100
200
300
400
500
9
VIN = 250 mV p-p
8
7
6
VIN = 100 mV p-p
5
4
3
2
1
0
−1
0
600
FREQUENCY (MHz)
1
4
8
12
16
20
50 100 200 300 400 500 600
FREQUENCY (MHz)
Figure 9. Remote Temperature Error vs.
Differential-mode Noise Frequency
Figure 10. Local Sensor Temperature Error vs.
Power Supply Noise Frequency
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ADM1029
TYPICAL PERFORMANCE CHARACTERISTICS
120
110
32
100
26
24
22
TEMPERATURE (C)
SUPPLY CURRENT (mA)
30
28
20
18
16
14
12
10
8
6
4
2
0
90
80
70
60
50
40
30
20
1.0
1.4
1.8
2.2
2.6
3.0
3.4
3.8
4.2
10
0
4.6
0
1
2
3
SUPPLY VOLTAGE (V)
ERROR (C)
1.65
1.60
1.55
1.50
1.45
1.40
1.35
1.30
0.10
0.00
−0.10
−0.20
−0.30
−0.40
−0.50
−0.60
−0.70
−0.80
−0.90
−1.00
−1.10
−1.20
2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0
0
20
40
SUPPLY VOLTAGE (V)
7
8
9
60
80
85
10
100 105 120
TEMPERATURE (C)
Figure 13. Supply Current vs. Supply Voltage
ERROR (C)
SUPPLY CURRENT (mA)
1.75
1.70
0
6
Figure 12. ADM1029 Response to Thermal Shock
1.80
0.05
0.00
−0.05
−0.10
−0.15
−0.20
−0.25
−0.30
−0.35
−0.40
−0.45
−0.50
−0.55
−0.60
5
TIME (Seconds)
Figure 11. Standby Supply Current vs. Supply
Voltage
1.25
1.20
1.15
1.10
1.05
1.00
4
20
40
Figure 14. Remote Temperature Error
60
80
85
100 105 120
TEMPERATURE (C)
Figure 15. Local Temperature Error
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ADM1029
Functional Description
voltage on Pin 18 (TMIN/INSTALL), which controls the
automatic fan speed control function, and also tells the
ADM1029 how many fans should be installed, as described
later.
If several ADM1029s are used in a system, their ADD
inputs can tap off a single potential divider, as shown in
Figure 17.
Serial Bus Interface
Control of the ADM1029 is carried out via the serial bus.
The ADM1029 is connected to this bus as a slave device,
under the control of a master device.
The ADM1029 has a 7-bit serial bus address. The four
MSBs of the address are set to 0101. The three LSBs can be
set by the user to give a total of eight different addresses,
allowing up to eight ADM1029s to be connected to a single
serial bus segment.
To minimize device pin count and size, the three LSBs are
set using a single pin (ADD, Pin 15). This is an 8-level input
whose input voltage is set by a potential divider. The voltage
on ADD is sampled immediately after power-up and
digitized by the on-chip ADC to determine the value of the
3 LSBs. Since ADD is sampled only at power-up, any
changes made while power is on will have no effect.
VCC
ADD
ADDRESS XXXX111
1.5 kW
ADD
ADDRESS XXXX110
1 kW
ADD
ADDRESS XXXX101
ADM1029#1
ADM1029#2
ADM1029#3
1 kW
ADD
ADDRESS XXXX100
VCC
ADM1029#4
1 kW
ADD
ADDRESS XXXX011
R1
ADM1029#5
1 kW
ADD
ADD
ADDRESS XXXX010
ADM1029
ADM1029#6
1 kW
R2
ADD
ADDRESS XXXX001
ADM1029#7
1.5 kW
GND
ADD
ADDRESS XXXX000
ADM1029#8
Figure 16. Setting the Serial Address
GND
Table 5 shows resistor values for setting the 3 LSBs of the
serial bus address. The same principle is used to set the
Figure 17. Setting Address of up to Eight ADM1029s
Table 5. RESISTOR RATIOS FOR SETTING SERIAL BUS ADDRESS
3 MSBs of ADC
Ideal Ratio
R2/(R1 + R2)
R1 (kW)
R2 (kW)
Actual
R2/(R1 + R2)
Error (%)
Address
111
N/A
0

1
0
0101111
110
0.8125
18
82
0.82
+0.75
0101110
101
0.6875
22
47
0.6812
−0.63
0101101
100
0.5625
12
15
0.5556
−0.69
0101100
011
0.4375
15
12
0.4444
+0.69
0101011
010
0.3125
47
22
0.3188
+0.63
0101010
001
0.1875
82
18
0.18
−0.75
0101001
000
N/A

0
0
0
0101000
data transfer, i.e., whether data will be written to
or read from the slave device.
The peripheral whose address corresponds to the
transmitted address responds by pulling the data
line low during the low period before the ninth
clock pulse, known as the Acknowledge Bit. All
other devices on the bus now remain idle while the
selected device waits for data to be read from or
written to it. If the R/W bit is a 0, the master will
The serial bus 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 an address/data stream will follow. All slave
peripherals connected to the serial bus respond to
the START condition, and shift in the next eight
bits, consisting of a 7-bit address (MSB first) plus
an R/W bit, which determines the direction of the
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ADM1029
the master will pull the data line high during the
tenth clock pulse to assert a STOP condition. In
READ mode, the master device will override the
acknowledge bit by pulling the data line high
during the low period before the ninth clock pulse.
This is known as No Acknowledge. The master
will then take the data line low during the low
period before the tenth clock pulse, high during the
tenth clock pulse to assert a STOP condition.
write to the slave device. If the R/W bit is a 1 the
master will read from the slave device.
2. Data is sent over the serial bus in sequences of
nine clock pulses, eight bits of data followed by an
acknowledge bit from the slave device. Transitions
on the data line must occur during the low period
of the clock signal and remain stable during the
high period, as a low-to-high transition when the
clock is high may be interpreted as a STOP signal.
The number of data bytes that can be transmitted
over the serial bus in a single READ or WRITE
operation is limited only by what the master and
slave devices can handle.
3. When all data bytes have been read or written,
stop conditions are established. In WRITE mode,
Any number of bytes of data may be transferred over the
serial bus in one operation, but it is not possible to mix read
and write in one operation, because the type of operation is
determined at the beginning and cannot subsequently be
changed without starting a new operation.
1
9
1
9
SCL
SDA
0
1
0
A2
1
A0
A1
D6
D7
R/W
START BY
MASTER
D4
D5
D2
D3
D1
D0
ACK. BY
ADM1029
FRAME 1
SERIAL BUS ADDRESS BYTE
ACK. BY
ADM1029
FRAME 2
ADDRESS POINTER REGISTER BYTE
1
9
SCL (CONTINUED)
D7
SDA (CONTINUED)
D4
D5
D6
D2
D3
D1
D0
ACK. BY
ADM1029
FRAME 3
DATA BYTE
STOP BY
MASTER
Figure 18. Writing a Register Address to the Address Pointer Register,
then Writing Data to the Selected Register
1
9
9
1
SCL
SDA
0
1
0
A2
1
A1
A0
START BY
MASTER
D7
R/W
D6
D4
D5
D3
D2
D1
D0
ACK. BY
ADM1029
ACK. BY
ADM1029
FRAME 1
SERIAL BUS ADDRESS BYTE
STOP BY
MASTER
FRAME 2
ADDRESS POINTER REGISTER BYTE
Figure 19. Writing to the Address Pointer Register Only
9
1
9
1
SCL
SDA
START BY
MASTER
0
1
0
1
A2
A1
A0
FRAME 1
SERIAL BUS ADDRESS BYTE
R/W
D7
D6
ACK. BY
ADM1029
D5
D4
D3
D2
FRAME 2
DATA BYTE FROM ADM1029
Figure 20. Reading Data from a Previously Selected Register
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9
D1
D0
STOP BY
NO ACK.
BY MASTER MASTER
ADM1029
In the case of the ADM1029, write operations contain
either one or two bytes, and read operations contain one
byte, and perform the following functions:
To write data to one of the device data registers or read
data from it, the Address Pointer Register must be set so that
the correct data register is addressed, data can be written into
that register or read from it. The first byte of a write
operation always contains an address that is stored in the
Address Pointer Register. If data is to be written to the
device, the write operation contains a second data byte that
is written to the register selected by the address pointer
register.
This is illustrated in Figure 18. The device address is sent
over the bus followed by R/W set to 0. This is followed by
two data bytes. The first data byte is the address of the
internal data register to be written to, which is stored in the
Address Pointer Register. The second data byte is the data to
be written to the internal data register.
When reading data from a register there are two
possibilities:
1. If the ADM1029’s Address Pointer Register value
is unknown or not the desired value, it is first
necessary to set it to the correct value before data
can be read from the desired data register. This is
done by performing a write to the ADM1029 as
before, but only the data byte containing the
register address is sent, as data is not to be written
to the register. This is shown in Figure 19.
A read operation is then performed consisting of
the serial bus address, R/W bit set to 1, followed
by the data byte read from the data register. This is
shown in Figure 20.
2. If the Address Pointer Register is known to be
already at the desired address, data can be read
from the corresponding data register without first
writing to the Address Pointer Register, so
Figure 19 can be omitted.
back to the host processor, so the device asserting INT can
be identified immediately.
If more than one device is asserting INT, all devices will
try to respond with their slave address, but an arbitration
process ensures that only the lowest address will be received
by the host.
After sending its slave address, the first device will then
clear its INT output. The host can then check if the INT is
still low and send the general call again if necessary until all
devices asserting INT have responded.
The ARA function can be disabled by setting Bit 2 of the
Configuration Register (address 01h).
Temperature Measurement System
Local Temperature Measurement
The ADM1029 contains an on-chip bandgap temperature
sensor, whose output is digitized by the on-chip ADC. The
temperature data is stored in the Local Temp Value Register
(address A0h). As both positive and negative temperatures
can be measured, the temperature data is stored in two’s
complement format, as shown in Table 6. Theoretically, the
temperature sensor and ADC can measure temperatures
from –128C to +127C with a resolution of 1C, but
temperatures outside the operating temperature range of the
device cannot be measured by the internal sensor.
Remote Temperature Measurement
The ADM1029 can measure the temperature of one or two
remote diode-connected transistors, connected to Pins 13
and 14 and/or 16 and 17. The data from the temperature
measurements is stored in the Remote 1 and Remote 2 Temp
Value Registers (addresses A1h and A2h).
If two remote temperature measurements are not required,
Pins 16 and 17 can be reconfigured as general-purpose logic
I/O pins, as explained later.
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. The absolute
value of VBE varies from device to device and individual
calibration is required to null this out so, unfortunately, the
technique is unsuitable for mass production.
The technique used in the ADM1029 is to measure the
change in VBE when the device is operated at two different
currents.
This is given by:
NOTE: although it is possible to read a data byte from a data
register without first writing to the Address Pointer Register,
if the Address Pointer Register is already at the correct
value, it is not possible to write data to a register without
writing to the Address Pointer Register, because the first
data byte of a write is always written to the Address Pointer
Register.
Alert Response Address
The ADM1029 has an interrupt (INT) output that is
asserted low when a fault condition occurs. Several INT
outputs can be wire OR’d to a common interrupt line. When
the host processor receives an interrupt request, it would
normally need to read the interrupt status register of each
device to identify which device had made the interrupt
request. However, the ADM1029 supports the optional
Alert Response Address function of the SMBus protocol.
When the host processor receives an interrupt request it can
send a general call address (0001100) over the bus. The
device asserting INT will then send its own slave address
DV BE + KTńq
ln(N)
(eq. 1)
where:
K is Boltzmann’s constant
q is charge on the carrier
T is absolute temperature in Kelvins
N is ratio of the two currents
Figure 21 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,
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10
ADM1029
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.
provided for temperature monitoring on some
microprocessors, but it could equally well be a discrete
transistor.
If a discrete transistor is used, the collector will not be
grounded, and should be linked to the base. If a PNP
I
NI
VDD
IBIAS
VOUT+
D+
REMOTE
SENSING
TRANSISTOR
To ADC
D−
BIAS
DIODE
VOUT−
LOW-PASS FILTER
fC = 65 kHz
Figure 21. Signal Conditioning for Remote Diode Temperature Sensors
Temperature Limits
To prevent ground noise interfering with the
measurement, the more negative terminal of the sensor is not
referenced to ground, but biased above ground by an internal
diode at the D– input. If the sensor is used in a noisy
environment, a capacitor of value up to 1000 pF may be
placed between the D+/D– pins.
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
two’s complement format. To further reduce the effects of
noise, digital filtering is performed by averaging the results
of 16 measurement cycles. An external temperature
measurement takes nominally 9.6 ms.
The results of external temperature measurements are
stored in 8-bit, two’s complement format, as illustrated in
Table 6.
The contents of the Local and Remote Temperature Value
Registers (addresses A0h to A2h) are compared to the
contents of the High and Low Limit Registers at addresses
90h to 92h and 98h to 9Ah. How the ADM1029 responds to
overtemperature/undertemperature conditions depends on
the status of the Temperature Fault Action Registers
(addresses 40h to 42h). The response of CFAULT, INT, and
fan-speed-to-temperature events depends on the setting of
these registers, as explained later.
Table 6. TEMPERATURE DATA FORMAT
Offset Registers
Digital noise and other error sources can cause offset
errors in the temperature measurement, particularly on the
remote sensors. The ADM1029 offers a way to minimize
these effects. The offsets on the three temperature channels
can be measured during system characterization and stored
as two’s complement values in three offset registers at
addresses 30h to 32h. The offset values are automatically
added to, or subtracted from, the temperature values,
depending on whether the two’s complement number
corresponds to a positive or negative offset. Offset values
from –15C to +15C are allowed.
The default value in the offset registers is zero, so if no
offsets are programmed, the temperature measurements are
unaltered.
Temperature
Digital Output
−128C
1000 0000
−125C
1000 0011
−100C
1001 1100
−75C
1011 0101
−50C
1100 1110
−25C
1110 0111
0C
0000 0000
+10C
0000 1010
+25C
0001 1001
+50C
0011 0010
+75C
0100 1011
+100C
0110 0100
+125C
0111 1101
+127C
0111 1111
Layout Considerations
Digital boards can be electrically noisy environments, and
care must be taken to protect the analog inputs from noise,
particularly when measuring the very small voltages from a
remote diode sensor. The following precautions should be
taken:
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ADM1029
Temperature-related Registers
1. Place the ADM1029 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.
2. 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.
3. Use wide tracks to minimize inductance and
reduce noise pickup. Ten mil track minimum
width and spacing is recommended.
GND
D+
D−
GND
Table 7 is a list of registers on the ADM1029 that are
specific to temperature measurement and control.
Table 7. TEMPERATURE-SPECIFIC REGISTERS
Address
Description
0x06
Temp Devices Installed
0x30
Local Temp Offset
0x31
Remote 1 Temp Offset
0x32
Remote 2 Temp Offset
0x40
Local Temp Fault Action
0x41
Remote 1 Temp Fault Action
10 MIL
0x42
Remote 2 Temp Fault Action
10 MIL
0x48
Local Temp Cooling Action
10 MIL
0x49
Remote 1 Temp Cooling Action
10 MIL
0x4A
Remote 2 Temp Cooling Action
10 MIL
0x80
Local Temp TMIN
10 MIL
0x81
Remote 1 Temp TMIN
10 MIL
0x82
Remote 2 Temp TMIN
0x88
Local Temp TRANGE/THYST
0x89
Remote 1 Temp TRANGE/THYST
0x8A
Remote 2 Temp TRANGE/THYST
0x90
Local Temp High Limit
0x91
Remote 1 Temp High Limit
0x92
Remote 2 Temp High Limit
0x98
Local Temp Low Limit
0x99
Remote 1 Temp Low Limit
0x9A
Remote 2 Temp Low Limit
0xA0
Local Temp Value
0xA1
Remote 1 Temp Value
0xA2
Remote 2 Temp Value
Figure 22. Arrangement of Signal Tracks
4. Try to minimize the number of copper/solder
joints, which can cause thermocouple effects.
Where copper/solder joints are used, make sure
that they are in both the D+ and D– path and at the
same temperature.
Thermocouple effects should not be a major
problem as 1C corresponds to about 240 mV, and
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.
5. Place 0.1 mF bypass and 1000 pF input filter
capacitors close to the ADM1029.
6. If the distance to the remote sensor is more than
8 inches, the use of twisted pair cable is
recommended. This will work up to about
6 to 12 feet.
7. For really 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
ADM1029. Leave the remote end of the shield
unconnected to avoid ground loops.
The flowchart in Figure 23 shows how to configure the
ADM1029 to measure temperature. It also shows how to
configure the ADM1029’s behavior for out-of-limit
temperature measurements.
Fan Interfacing
The ADM1029 can be interfaced to many types of fan. It
can be used to control the speed of a simple two-wire fan. It
can measure the speed of a fan with a tach output, and it can
accept a logic input from fans with a FAULT output. By
means of a shorting link in the fan connector it can also
determine if a fan is present or not and if fans have been
hot-swapped.
The ADM1029 can control or monitor one or two fans.
Bits 0 and 1 of the Fans Supported In System Register (03h)
tell the ADM1029 how many fans it should be
controlling/monitoring.
In the following descriptions “installed” means that the
corresponding bit of register 03h is set and the ADM1029
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. 1 W series
resistance introduces about 0.5C error.
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ADM1029
asserting INT or CFAULT, but will still be reflected in the
corresponding Fan Status Register.
Setting Bit 0 indicates that Fan 1 is installed and is set to
1 at power-up by default. Setting Bit 1 indicates that Fan 2
is installed and depends on the state of Pin 18
(TMIN/INSTALL) at power-up.
expects to see a fan interfaced to it. It does not necessarily
mean that the fan is actually, physically, connected.
If a fan is installed, events such as a fault output and
hot-swapping of the fan can cause INT and CFAULT to be
asserted, unless they are masked for that particular event. If
a fan is not installed, but is still physically connected to the
ADM1029, these events will be ignored with respect to
DEFAULTS
LOCAL = 605C
REMOTE 1 = 705C
REMOTE 2 = 705C
CONFIGURE
TEMPERATURE LOW
LIMITS
LOCAL (REG 0X98)
REMOTE 1 (REG 0X99)
REMOTE 2 (REG 0X9A)
DEFAULTS
LOCAL = 805C
REMOTE 1 = 1005C
REMOTE 2 = 1005C
CONFIGURE
TEMPERATURE HIGH
LIMITS
LOCAL (REG 0X90)
REMOTE 1 (REG 0X91)
REMOTE 2 (REG 0X92)
BIT 0 = 1
BIT 1 = 1
BIT 2 = 1
BIT 3 = 0
BIT 3 = 1
BIT 4 = 1
BIT 5 = 1
BIT 6 = 1
BIT 7
7
ASSERT CFAULT ON OVER-TEMPERATURE
RUN FAN(S) ALARM SPEED ON OVER-TEMPERATURE
ASSERT INT ON OVER-TEMPERATURE
ALARM BELOW LOW TEMP LIMIT
ALARM ABOVE LOW TEMP LIMIT
ASSERT CFAULT WHEN LOW TEMP LIMIT CROSSED
RUN FAN ALARM SPEED ON UNDER-TEMPERATURE
ASSERT INT ON UNDER-TEMPERATURE
LATCHES A TEMPERATURE OUT-OF-LIMIT EVENT
6
5
4
3
2
1
0
IS
TEMPERATURE
>
HIGH LIMIT?
CONFIGURE
TEMPERATURE FAULT
ACTION
LOCAL (REG 0X40)
REMOTE 1 (REG 0X41)
REMOTE 2 (REG 0X42)
IS
TEMPERATURE
>
HIGH LIMIT?
YES
CFAULT
FANS RUN
ALARM SPEED
IS
TEMPERATURE
>
HIGH LIMIT?
CONFIGURE
TEMPERATURE COOLING
ACTION
LOCAL (REG 0X48)
REMOTE 1 (REG 0X49)
REMOTE 2 (REG 0X4A)
DEFAULTS
LOCAL = 05C
REMOTE 1 = 05C
REMOTE 2 = 05C
YES
YES
ALARM ABOVE
OR BELOW LOW
TEMP LIMIT?
CONFIGURE
TEMPERATURE OFFSETS
LOCAL (REG 0X30)
REMOTE 1 (REG 0X31)
REMOTE 2 (REG 0X32)
INT
0 = ALARM BELOW TEMP LIMIT
1 = ALARM ABOVE TEMP LIMIT
LOW TEMP LIMT
CROSSED?
MEASURE
TEMPERATURE
LOCAL (REG 0XA0)
REMOTE 1 (REG 0XA1)
REMOTE 2 (REG 0XA2)
CFAULT
YES
LOW TEMP LIMT
CROSSED?
YES
FANS RUN ALARM SPEED
LOW TEMP LIMT
CROSSED?
YES
INT
AUTOMATIC FAN SPEED CONTROL (SEE TABLE 15 LATER)
BIT 0 = 1
BIT 1 = 1
X
FAN 1 RUNS AT ALARM SPEED FOR OUT-OF-LIMIT TEMPERATURE EVENTS;
OTHERWISE, FAN 1 RUNS AT SPEED DETERMINED BY AUTOMATIC FAN CONTROL
FAN 2 RUNS AT ALARM SPEED FOR OUT-OF-LIMIT TEMPERATURE EVENTS;
OTHERWISE, FAN 2 RUNS AT SPEED DETERMINED BY AUTOMATIC FAN CONTROL
X
X
X
X
X
1
0
Figure 23. Temperature Sensing Flowchart
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ADM1029
by gating an onchip oscillator into the input of an 8-bit
counter.
The fan speed measuring circuit is initialized on the first
rising edge of a fan tach pulse after monitoring is enabled by
setting Bit 4 of the Configuration Register. It then starts
counting on the rising edge of the second tach pulse and
counts for four fan tach periods, until the rising edge of the
sixth tach pulse, or until the counter overranges if the fan
tach period is too long.
After the speed of the first fan has been measured, the
speed of the second fan (if installed) will be measured in the
same way. The measurement cycle will repeat until
monitoring is disabled. The fan speed measurements are
stored in the Fan Tach Value registers at addresses 70h and
71h.
If both fans are installed, Fan 1 will be measured first. If
only one fan is installed, the ADM1029 will still try to
measure both fans, starting with Fan 1, but the measurement
on the noninstalled fan will time out when the Fan Tach
Value count overranges.
The fan speed count is given by:
If two fans are installed, Bit 0 would be 1 by default and
Pin 18 would be tied high* to set Bit 1. If only one fan is
installed, it would normally be Fan 1 and Pin 18 would be
tied low* to clear Bit 1. However, both of these bits can be
modified by writing to the register, so it is possible to have
Fan 2 installed and not Fan 1, or even have no fans installed.
* Note that Pin 18 also sets TMIN for automatic fan speed control. If
this function is used, Pin 18 would be set to some other level
according to Table 13.
FAULT Inputs/Outputs
The ADM1029 can be used with fans that have a fault
output which indicates if the fan has stalled or failed. If one
or both of the FAULT inputs (Pin 2 or Pin 23) goes low, both
INT and CFAULT will be asserted.
Events on the fault inputs are also reflected in Bits 2 and
3 of the corresponding Fan Status Registers at addresses 10h
and 11h. Bit 2 reflects the inverse state of the FAULT pin (0
if FAULT is high, 1 if FAULT is low), while Bit 3 is latched
high if a FAULT input goes low. It must be cleared by writing
a zero to it.
If the fan(s) being used do not have a FAULT output, the
FAULT input(s) on the ADM1029 should be pulled high to
VCC.
The FAULT pins can also be configured as open-drain
outputs by setting Bit 5 of the corresponding Fan Fault
Action Register (18h or 19h). If a FAULT pin is configured
as an output, it will still function as an input. This means that
when a fault input occurs it will be latched low by the fault
output, even if the fault input is removed. The fault output
can be used to drive a fan failure indicator such as an LED.
If the FAULT pin is used as an output, any input to the
FAULT pin should also be open-drain. This will avoid the
fault input trying to source a high current into the FAULT pin
if the fault input goes high while the fault output is low.
Count + f
4
(eq. 2)
60ńRńN
where:
f is oscillator frequency in Hz
factor 4 is because 4 tach periods are counted
factor 60 is to convert minutes to seconds
R = fan speed in RPM
N is number of tach pulses per revolution
The frequency of the oscillator can be adjusted to suit the
expected frequency range of the fan tach pulses, which
depends on the fan speed and the number of tach pulses
produced for each revolution of the fan, which is either 1, 2,
or 4. The oscillator frequency is set by Bits 7 and 6 of the Fan
Configuration Registers (68h for Fan 1 and 69h for Fan 2).
Fan Present Inputs
The fan PRESENT signal is implemented by a shorting
link to ground in the fan connector. When the fan is plugged
in, the corresponding PRESENT input (Pin 4 or Pin 21) on
the ADM1029 is pulled low. If the fan is unplugged, the
PRESENT input will be pulled high. INT and CFAULT will
be asserted (unless masked) and the event will be reflected
in Bits 0 and Bit 1 of the corresponding Fan Status Register.
Appearance or disappearance of a PRESENT input signal
during normal operation signals to the ADM1029 that a fan
has been hot-plugged or unplugged. INT and CFAULT will
be asserted (unless masked). When a fan is hot-plugged,
Bit 7 of the corresponding Fan Status Register will be set
and a Fan Free Wheel Test commences automatically.
Table 8. OSCILLATOR FREQUENCIES
Bit 7
Bit 6
Oscillator Frequency (Hz)
0
0
Measurement Disabled
0
1
470
1
0
940
1
1
1880
CLOCK
CONFIG
REG. BIT 4
FAN 1
TACH
Fan Speed Measurement
FAN 2
TACH
The fan counter does not count the fan tach output pulses
directly, because at low fan speeds it would take several
seconds to accumulate a reasonably large and accurate
count. Instead, the period of the fan revolution is measured
START OF
MONITORING
CYCLE
FAN 1
MEASUREMENT
PERIOD
FAN 2
MEASUREMENT
PERIOD
Figure 24. Fan Speed Measurement
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ADM1029
Fan Speed Limits
Figures 25 a to 28 show circuits for most common fan tach
outputs.
If the fan tach output has a resistive pull-up to VCC, it can
be connected directly to the fan input, as shown in Figure 25.
Fans generally do not overspeed 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 Tach Limit
Registers for the fans. These registers are at address 78h for
Fan 1 and 79h for Fan 2. It should be noted that, since fan
period rather than speed is being measured, the fan speed
count will be larger the slower the fan speed. Therefore a fan
failure fault will occur when the measurement exceeds the
limit value.
For the most accurate fan failure indication, the oscillator
frequency should be chosen to give as large a limit value as
possible without the counter overranging. A count close to
¾ full-scale or 191 is the optimum value.
For example, if a fan produces two tach pulses per
revolution and the fan failure speed is to be 600 rpm, the
oscillator frequency should be set to 940 Hz. This will give
a count at the fail speed of:
940
4
60ń600ń2 + 188
12 V
PULL-UP
4.7 kW
TYP
TACH1
OR TACH 2
TACH
OUTPUT
FAN SPEED
COUNTER
Figure 25. Fan with Tach Pull-up to +VCC
If the fan output has a resistive pull-up to 12 V (or other
voltage greater than 6.5 V), the fan output can be clamped
with a Zener diode, as shown in Figure 26. The Zener
voltage should be chosen so that it is greater than VIH but less
than 6.5 V, allowing for the voltage tolerance of the Zener.
A value of between 3 V and 5 V is suitable.
(eq. 3)
If the oscillator frequency were only 470 Hz, the count
would be 94, while an oscillator frequency of 1880 Hz
cannot be used because the count would be 376 and the
counter would overrange.
12 V
VCC
PULL-UP
4.7 kW
TYP
Fan Monitoring Cycle Time
Five complete tach periods are required to carry out a fan
speed measurement Therefore, if the start of a fan
measurement just misses a rising edge, the measurement can
take almost six tach periods for each fan.
The worst-case monitoring cycle time is when both fans
are under speed and the fan speed counter counts up to its
maximum value. The actual count takes 256 oscillator
pulses over four tach periods, plus a further two tach periods
or 128 oscillator pulses before the count starts. The total
monitoring cycle time is therefore:
t MEAS + 384ńf OSC(FAN 1) ) 384ńf OSC(FAN 2)
VCC
TACH
OUTPUT
TACH1
OR
TACH 2
FAN SPEED
COUNTER
ZD1*
ZENER
* Choose ZD1 Voltage Approx. 0.8  VCC
Figure 26. Fan with Tach. Pull-up to Voltage > 6.5 V
(e.g., 12 V) Clamped with Zener Diode
If the fan has a strong pull-up (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 27. Alternatively, a
resistive attenuator may be used, as shown in Figure 28.
R1 and R2 should be chosen such that:
(eq. 4)
In order to read a valid result from the Fan Tach Value
Registers, the total monitoring time allowed after starting
the monitoring cycle should be greater than this.
2 V t V PULLUP
Tach Signal Conditioning
R2ń(R PULLUP ) R1 ) R2) t 5 V (eq. 5)
The fan inputs have an input resistance of nominally
160 kW to ground, so this should be taken into account when
calculating resistor values.
With a pull-up voltage of 12 V and pull-up resistor less
than 1 kW, suitable values for R1 and R2 would be 100 kW
and 47 kW. This will give a high input voltage of 3.83 V.
Signal conditioning in the ADM1029 accommodates the
slow rise and fall times typical of fan tachometer outputs.
The maximum input signal range is 0 V to 5 V, even if VCC
is less than 5 V. In the event that these inputs are supplied
from fan outputs that exceed 0 V to 5 V, either resistive
attenuation of the fan signal or diode clamping must be
included to keep inputs within an acceptable range.
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ADM1029
12 V
at which a fan will run in automatic control mode. These bits
should be set to 05h. This corresponds to 33% PWM
duty-cycle, which is the lowest speed at which most fans will
run reliably.
Fan(s) will run at minimum speed if there is no fault
condition, automatic fan speed is disabled, and there are no
other overriding conditions.
VCC
TACH
OUTPUT
PULL-UP
TYP < 1 kW
OR TOTEM-POLE
R1
10 kW
TACH1
OR
TACH 2
FAN SPEED
COUNTER
ZD1*
ZENER
Alarm Speed
Alarm speed is set by the four MSBs of the Fan 1 and
Fan 2 Minimum/Alarm Speed Registers (addresses 60h,
61h). Fan(s) will run at alarm speed if any of the following
conditions occurs, assuming the condition has not been
masked out using the Fan Event Mask Registers:
 Setting Bit 0 of register 07h forces Fan 1 to run at alarm
speed (Set Fan x Alarm Speed Register).
 Setting Bit 1 of register 07h forces Fan 2 to run at alarm
speed (Set Fan x Alarm Speed Register).
If monitoring is disabled by clearing Bit 4 of the
Configuration Register, all fans controlled by the
ADM1029 will run at alarm speed.
 When a GPIO pin is configured as an input by setting
Bit 0 of the corresponding GPIO Behavior Register,
and Bit 4 of the GPIO Behavior Register is also set, all
fans controlled by the ADM1029 will go to alarm speed
when the logic input is asserted (high or low, depending
on the polarity bit, Bit 1 of the corresponding GPIO
Behavior Register).
 If Bit 7 of a Fan Fault Action Register is set
(18h − Fan 1, 19h − Fan 2) the corresponding fan will
go to alarm speed when CFAULT is pulled low by an
external source.
 If a tach measurement exceeds the set limit, all fans
controlled by the ADM1029 will run at alarm speed.
 If a fan fault input pin is asserted (low), all fans
controlled by the ADM1029 will run at alarm speed.
 If Bit 1 of a Temp. Fault Action Register is set
(40h − Local Sensor, 41h − Remote 1, 42h − Remote 2),
all fans controlled by the ADM1029 will go to alarm
speed if the corresponding temperature high limit is
exceeded.
 If Bit 5 of a Temp. Fault Action Register is set, all fans
controlled by the ADM1029 will go to alarm speed if a
temperature input crosses the corresponding
temperature low limit, the direction depending on the
setting of Bit 3 of the Temp. Control register.
(0 = alarm when input goes below low limit, 1 = alarm
when input goes above low limit).
 If Bit 1 of an AIN Behavior Register is set
(50h − AIN0, 51h − AIN1), all fans controlled by the
ADM1029 will go to alarm speed if the corresponding
AIN high limit is exceeded.
 If Bit 5 of an AIN Behavior Register is set, all fans
controlled by the ADM1029 will go to alarm speed if
* Choose ZD1 Voltage Approx. 0.8  VCC
Figure 27. Fan with Strong Tach. Pull-up to > VCC or
Totem-pole Output, Clamped with Zener and Resistor
12 V
VCC
< 1 kW
TACH
OUTPUT
TACH1
OR
TACH 2
R1*
FAN SPEED
COUNTER
R2*
* See Text
Figure 28. Fan with Strong Tach. Pull-up to > VCC or
Totem-pole Output, Attenuated with R1/R2
Fan Speed Control
Fan speed is controlled using pulsewidth modulation
(PWM). The PWM outputs (Pins 1 and 24) give a pulse
output with a programmable frequency (default 250 Hz) and
a duty-cycle defined by the contents of the relevant fan speed
register, or by the automatic fan speed control when this
mode is enabled. The speed at which a fan runs is determined
by fault conditions and the settings of various control and
mask registers.
A fan can only be driven if it is defined as being supported
by the controller in register 02h. The ADM1029 supports up
to two fans, so Bits 0 and 1 of this register are permanently
set. This register is read-only.
A fan will only be driven if it is defined as being supported
by the system in register 03h. If Bit 0 of this register is set,
it indicates that Fan 1 is installed. This is the power-on
default. If Bit 1 is set, it indicates that Fan 2 is installed. This
bit is set by the state of Pin 18 at power-up. This register is
read/write and the default/power-on setting can be
overwritten. If a fan is not supported in register 03h it will
not be driven, even if it is physically installed.
The PWM outputs are open-drain outputs. They require
pull-up resistors and must be amplified and buffered to drive
the fans.
Minimum Speed
The normal operating fan speed is set by the four LSBs of
the Fan 1 and Fan 2 Minimum/Alarm Speed Registers
(addresses 60h, 61h). These bits also set the minimum speed
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ADM1029

Fan 1 and Fan 2 speed. Similarly, Bits 0 and 1 of register 21h
enable (bit set) or mask (bit clear) the effect of a Fan 2 Fault
on Fan 1 and Fan 2 speed.
Registers 38h to 3Eh are GPIO X Event Mask Registers.
Bits 0 and 1 of these registers enable or mask the effect of a
GPIO assertion on Fan 1 and Fan 2 speed.
an analog input crosses the corresponding AIN low
limit, the direction depending on the setting of Bit 3 of
the AIN control register. (0 = alarm when input goes
below low limit, 1 = alarm when input goes above low
limit).
If a thermal override occurs while the ADM1029 is in
sleep mode, all fans controlled by the ADM1029 will
run at alarm speed.
NOTE:
Hot-plug Speed
Hot-plug speed is set by the four LSBs of the Fan 1 and
Fan 2 Configuration Registers (addresses 68h and 69h). The
PWM frequency is set by Bits 4 and 5 of these registers,
while Bits 6 and 7 set the number of pulses per revolution for
fan speed measurement.
Fan(s) will run at hot-plug speed if any of the following
conditions occur, assuming the condition has not been
masked using the Fan Event Mask Registers:
 If a fan is unplugged, the other fan (if any) controlled
by the ADM1029 will run at hot-plug speed.
 Setting Bit 0 of register 08h forces Fan 1 to run at
hot-plug speed (Set Fan x Hot-plug Speed).
 Setting Bit 1 of register 08h forces Fan 2 to run at
hot-plug speed (Set Fan x Hot-plug Speed).
 When a GPIO pin is configured as an input by setting
Bit 0 of the corresponding GPIO Behavior Register,
and Bit 5 of the GPIO Behavior Register is also set, all
fans controlled by the ADM1029 will go to hot-plug
speed when the logic input is asserted (high or low,
depending on the polarity bit, Bit 1 of the
corresponding GPIO Behavior Register).
 If Bit 6 of a Fan Fault Action Register is set (18h for
Fan 1, 19h for Fan 2) the corresponding fan will go to
hot-plug speed when CFAULT is pulled low by an
external source.
Registers 48h to 4Ah are Temp. Cooling Action Registers.
Bits 0 and 1 of these registers enable or mask the effect of
Local, Remote 1, and Remote 2 temperature faults on
Fan 1 and Fan 2 speed. These registers also determine
which temperature channel controls each fan in automatic
fan speed control mode, as described later.
Registers 58h and 59h are AIN Event Mask Registers.
Bits 0 and 1 of these registers enable or mask the effect of an
AIN out-of-limit event on Fan 1 and Fan 2 speed.
Modes of Operation
The ADM1029 has three different modes of operation.
These modes determine the behavior of the system.
1. PWM Duty Cycle Select Mode (directly sets fan speed
under software control)
2. Thermal Trip Mode
3. Automatic Fan Speed Control Mode
PWM Duty Cycle Select Mode
The ADM1029 may be operated under software control
by clearing bits <1:0> of the three Temp Cooling Action
Registers (Reg 0x48, 0x49, 0x4A). Once under Software
Control, each fan speed may be controlled by programming
values of PWM Duty Cycle in to the device. Values of PWM
Duty Cycle between 0% to 100% may be written to the four
LSBs of the Fan 1 and Fan 2 Minimum/Alarm Speed
Registers (addresses 60h, 61h). to control the speed of each
fan. Table 9 shows the relationship between hex values
written to the Minimum/Alarm Speed Registers and PWM
duty cycle obtained.
Table 9. PWM DUTY CYCLE SELECT MODE
NOTE: if operating conditions and register settings are such that
both alarm speed and hot-plug speed would be triggered,
which one takes priority is determined by Bit 5 of the Fan 1
and Fan 2 Status Registers (addresses 10h and 11h). If this
bit is set, hot-plug speed takes priority. If it is cleared, alarm
speed takes priority.
Full Speed
Fans will run at full speed if the corresponding bits in the
Set Fan x Full Speed Register (address 09h) are set: Bit 0 for
Fan 1 and Bit 1 for Fan 2.
Hex Value
PWM Duty Cycle
00
0%
01
7%
02
14%
03
20%
04
27%
05
33% Recommended
06
40%
Fan Mask Registers
07
47%
The effect of various conditions on fan speed can be
enabled or disabled by mask registers. In all these registers,
setting Bit 0 of the register enables Fan 1 to go to alarm
speed or hot-plug speed if the corresponding event occurs,
while setting Bit 1 enables Fan 2. Clearing these bits masks
the effect of the corresponding event on fan speed.
Registers 20h and 21h are Fan Event Mask Registers.
Bits 0 and 1 of register 20h enable (bit set) or mask (bit clear)
the effect of a Fan 1 fault (underspeed or fault input) on
08
53%
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09
60%
0A
67%
0B
73%
0C
80%
0D
87%
0E
93%
0F
100% (Default)
ADM1029
2. Missing Fan. If a fan is missing, i.e., has been
unplugged, the Missing Latch bit (Bit 1 of
Fan x Status Registers) is set.
3. Hotplugged Fan. If a new fan is inserted into the
system, Bit 7 (Hotplug Latch bit) of the
Fan x Status Register is set.
4. FAULT Asserted. If the fan becomes stuck and its
FAULT output asserts low, Bit 2 (Fault Latch bit)
of the Fan x Status register is set.
5. TACH Failure. If the fan runs underspeed or
becomes stuck, then Bit 6 (Tach Fault Latch Bit)
of the Fan x Status Register is set.
It is recommended that the minimum PWM duty cycle be
set to 33% (0x05). This has been determined to be the lowest
PWM duty cycle that most fans will run reliably at. Note that
the PWM duty cycle values programmed in to these registers
also define the PWM duty cycle that the fans will turn on at,
in Automatic Fan Speed Control Mode. It is recommended
that after power-up, the PWM duty cycle is set to 33% before
enabling Automatic Fan Speed Control.
Thermal Trip Mode
The ADM1029 can thermally trip the fan(s) for simple
on/off fan control, or 2-speed fan control. For example, a fan
can be programmed to run at 33% duty cycle. If the
temperature exceeds the high temperature limit set for that
temperature channel, the fan can automatically trip and run
at Alarm Speed. The fan will continue to run at Alarm Speed
even if the temperature error condition subsides, until the
Latch Temp Fault bit (Bit 7 of the Temp x Fault Action Reg)
is cleared in software by writing a 0 to it. To configure Fan 1
normally, run at 33% but to thermally trip to Alarm Speed
for a Remote 2 measured temperature of 70C, set up the
following registers:
1. Configure the normal PWM duty cycle for Fan 1
to 33%.
Automatic Fan Speed Control
The ADM1029 has a local temperature channel and two
remote temperature channels, which may be connected to an
on-chip diode-connected transistor on a CPU or a
general-purpose discrete transistor. These three temperature
channels may be used as the basis for an automatic fan speed
control loop to drive fans using Pulsewidth Modulation
(PWM).
How Does The Control Loop Work?
The Automatic Fan Speed Control Loop is shown in
Figure 29.
Fan 1 MinimumńAlarm Speed Reg (0x60) + 0xF5
SPIN UP FOR 2 SECONDS
2. Set the Remote 2 High Temperature Limit = 70C.
MAX
Remote 2 Temp High Limit Reg (0x92) + 0x46
FAN SPEED
3. Configure Alarm Speed on Overtemperature
function for Remote 2 Temperature channel.
Set Bit 1 of Temp 2 Fault Action Reg (0x42)
4. Enable Fan 1 to be controlled by Remote 2
Temperature.
MIN
Set Bit 0 of Temp 2 Cooling Action Reg (0x4A)
Once the fan thermally trips to Alarm Speed, it will
continue to run at Alarm Speed until the temperature drops
below the High Temperature Limit and the Latch Temp Fault
bit (Bit 7 of the Temp 2 Fault Action Reg) is cleared to 0.
TMIN
TMAX = TMIN + TRANGE
TEMPERATURE
Figure 29. Automatic Fan Speed Control
In order for the fan speed control loop to work, certain
loop parameters need to be programmed in to the device:
1. TMIN. This is the temperature at which a fan
should switch on and run at minimum speed. The
fan will only turn on once the temperature being
measured rises above the TMIN value programmed.
The fan will spin up for a predetermined time
(default = 2 secs). See Fan Spin-up section for
more details.
2. TRANGE. This will be the temperature range over
which the ADM1029 will automatically adjust fan
speed. As the temperature increases beyond TMIN,
the PWM duty cycle will be increased accordingly.
Event Latch Bits
Certain events that occur will cause latch bits to be set in
various registers on the ADM1029. Once a latch bit is set, it
will need to be cleared by software for the system to return
to normal operation. To detect if a latch bit has been set, the
INT pin can be used to signal a latch event to the system
supervisor. Alternatively, the Status Registers can be polled
periodically, and any latch bits that are set can be cleared.
The events that cause latch bits to be set are:
1. Thermal Events. If the fan is run at Alarm Speed
on Overtemperature or Undertemperature, this will
set the Latch Temp Fault bit (Bit 7 of the
Temp x Fault Action Registers 0x40–0x42).
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ADM1029
The TRANGE parameter actually defines the fan
speed versus temperature slope of the control loop.
3. TMAX. This is defined as the temperature at which
a fan will be at its maximum speed. At this
temperature, the PWM duty cycle driving the fan
will be 100%. TMAX is given by TMIN + TRANGE.
Since this parameter is the sum of the TMIN and
TRANGE parameters, it does not need to be
programmed into a register on-chip.
4. Programmable hysteresis is included in the control
loop to prevent the fans continuously switching on
and off if the temperature is close to TMIN. The
fans will continue to run until such time as the
temperature drops below TMIN–THYST. The four
MSBs of the TRANGE/THYST registers (Registers
0x88, 0x89, 0x8A) contain a temperature
hysteresis value that can be programmed from
0001 to 1111. This allows a temperature hysteresis
range from 1C to 15C for each temperature
measurement channel.
100
A
47
40
33
0 5 10
TMIN
20
40
60
PWM DUTY CYCLE (%)
B
C
60
53
A − TRANGE = 40C
B − TRANGE = 40C
C − TRANGE = 40C
47
0 5 10
20
40
60
80
TMAX = TMIN + TRANGE
Fan Spin-up
As previously mentioned, once the temperature being
measured exceeds the TMIN value programmed, the fan will
turn on at minimum speed (default = 33% duty cycle).
However, the problem with fans being driven by PWM is
that 33% duty cycle is not enough to reliably start the fan
spinning. The solution is to spin the fan up for a
predetermined time, and once the fan has spun up, its
running speed may be reduced in line with the temperature
being measured.
The ADM1029 allows fan spin-up times between 1/64
second and 16 seconds. The Fan Spin-up Register (Register
0x0C) allows the spin-up time for the fans to be
programmed. Bit 3 of this register, when set, disables fan
spin-up for both fans.
A − TRANGE = 5C
B − TRANGE = 10C
C − TRANGE = 20C
D − TRANGE = 40C
E − TRANGE = 80C
53
A
66
Figure 31. Effect of Increasing TMIN Value on Control
Loop
66
60
73
TEMPERATURE (C)
E
73
80
TMIN
D
80
87
33
B
87
93
40
C
93
PWM DUTY CYCLE (%)
100
80
TMAX = TMIN + TRANGE
Table 10. FAN SPIN-UP TIMES
TEMPERATURE (C)
Figure 30. PWM Duty Cycle vs. Temperature Slopes
(TRANGE)
Figure 30 shows the different control slopes determined
by the TRANGE value chosen, and programmed in to the
ADM1029. TMIN was set to 0C to start all slopes from the
same point. It can be seen how changing the TRANGE value
affects the PWM Duty Cycle vs. Temperature Slope.
Figure 31 shows how for a given TRANGE, changing the
TMIN value affects the loop. Increasing the TMIN value will
increase the TMAX (temperature at which the fan runs full
speed) value, since TMAX = TMIN + TRANGE. Note,
however, that the PWM Duty Cycle versus Temperature
slope remains exactly the same. Changing the TMIN value
merely shifts the control slope.
Bits 2:0
Spin-up Times
(Fan Spin-up Register)
000
16 Seconds
001
8 Seconds
010
4 Seconds
011
2 Seconds (Default)
100
1 Second
101
1/4 Second
110
1/16 Second
111
1/64 Second
Once the Automatic Fan Speed Control Loop parameters
have been chosen, the ADM1029 device may be
programmed. The ADM1029 is placed into Automatic Fan
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ADM1029
Speed Control Mode by writing to the three Temperature
Cooling Action Registers (Registers 0x48, 0x49, 0x4A).
The device powers up in Automatic Fan Speed Control
Mode by default, as long as the TMIN/Install pin (Pin 18)
does not have the disable option selected (TMIN/Install pin
tied low or high). The default setting is that both fans will run
at the fastest speed calculated by all three temperature
channels. The control mode offers flexibility in that the user
can decide which temperature channel/channels control
each fan (five options).
PWM DUTY CYCLE (%)
100
1
80
73
66
60
53
47
33
Temperature Cooling Action
0
Bit 0 Register 0x48 and Bit 1 Register 0x48 = 1
Local Temp Controls Fan 1 and/or Fan 2
3
Bit 0 Register 0x49 and Bit 1 Register 0x49 =
Remote Temp 1 Controls Fan 1 and/or Fan 2
4
Bit 0 Register 0x4A and Bit 1 Register 0x4A =
Remote Temp 2 Controls Fan 1 and/or Fan 2
5
Bits 0, 1 Reg 0x48, 0x49, 0x4A = 1 Max Speed
Calculated by Local and Remote Temperature
Channels Controls Fans 1 and/or 2
87
TRANGE = 40C
Programming the Automatic Fan Speed Control Loop
73
1. Program a value for TMIN
2. Program a value for the slope TRANGE
3. TMAX = TMIN + TRANGE
4. Program a value for Fan Spin-up Time
5. Program the desired Automatic Fan Speed Control
Mode Behavior, i.e., which temperature channel
controls each fan
66
60
53
47
40
33
40
80
The local temperature’s TMAX will thus be 60C.
Figure 33 shows the control loop for the Remote 1
Temperature channel. Its TMIN value has been set to 0C,
while its TRANGE = 80C. Therefore, the Remote 1
Temperature’s TMAX value will be 80C.
If both temperature channels measure 40C, both control
loops will calculate a PWM duty cycle of 66%. Therefore,
the fans will be driven at 66% duty cycle.
If both temperature channels measure 20C, the local
channel will calculate 33% PWM duty cycle, while the
Remote 1 channel will calculate 50% PWM duty cycle.
Thus, the fans will be driven at 50% PWM duty cycle.
Consider the local temperature measuring 60C, while the
Remote 1 temperature is measuring 70C. The PWM duty
cycle calculated by the local temperature control loop will
be 100% (since the temperature = TMAX). The PWM duty
cycle calculated by the Remote 1 temperature control loop
at 70C will be approximately 90%. So the fans will run full
speed (100% duty cycle). Remember that the fan speed will
be based on the fastest speed calculated, and is not
necessarily based on the highest temperature measured.
Depending on the control loop parameters programmed, a
lower temperature on one channel may actually calculate a
faster speed than a higher temperature on another channel.
93
20
70
TMAX = TMIN + TRANGE
Figure 33. Max Speed Calculated by Remote
Temperature Control Loop Drive Fan
100
0
TMIN
40
REMOTE TEMPERATURE (C)
When Option 5 is chosen, this offers increased flexibility.
The Local and Remote temperature channels can have
independently programmed control loops with different
control parameters. Whichever control loop calculates the
fastest fan speed based on the temperature being measured,
drives both fans.
Figures 32 and 33 show how the fan’s PWM duty cycle is
determined by two independent control loops. This is the
type of Automode Fan Behavior seen when Bits 0 and 1 of
all three Temperature Cooling Action Registers = 11.
Figure 32 shows the control loop for the Local Temperature
channel. Its TMIN value has been programmed to 20C, and
its TRANGE value is 40C.
80
20
TMIN
Bit 0 Register 0x49 and/or Bit 1 Reg 0x4A =
Remote Temp 1 Controls Fan 1, Remote Temp 2
Controls Fan 2
2
PWM DUTY CYCLE (%)
87
40
Table 11. AUTOMATIC MODE FAN BEHAVIOR
Option
93
60
TMAX = TMIN + TRANGE
Other Control Loop Parameters?
LOCAL TEMPERATURE (C)
Having programmed all the above loop parameters, are
there any other parameters to worry about?
Figure 32. Max Speed Calculated by Local
Temperature Control Loop Drive Fan
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ADM1029
TMIN was defined as being the temperature at which a fan
switched on and ran at minimum speed. This minimum
speed should be set to 33%. If the minimum PWM duty cycle
is programmed to 33%, the fan control loops will operate as
previously described.
It should be noted, however, that changing the minimum
PWM duty cycle affects the control loop behavior.
will actually reach full speed at a much lower temperature,
28C. Case 3 shows that when the minimum PWM duty
cycle was increased to 73%, the temperature at which the fan
ran full speed was 16C. So the effect of increasing the
minimum PWM duty cycle, with a fixed TMIN and fixed
TRANGE, is that the fan will actually reach full speed (TMAX)
at a lower temperature than TMIN + TRANGE. How can
TMAX be calculated?
In Automatic Fan Speed Control Mode, the registers
holding the minimum PWM duty cycle at TMIN, are the
Minimum/Alarm Speed Registers (addresses 60h, 61h).
Table 12 shows the relationship between the decimal values
written to the Minimum/Alarm Speed Registers and PWM
duty cycle obtained.
PWM DUTY CYCLE (%)
100
93
87
80
3
73
66
TRANGE = 40C
2
60
The temperature at which each fan will run full speed
(100% duty cycle) is given by:
1
53
47
T MAX + T MIN ) ((Max DC * Min DC)
40
33
0
16
28
40
where:
TMAX
TMIN
Max DC
Min DC
60
TMIN
TEMPERATURE (C)
Figure 34. Effect of Changing Minimum Duty Cycle
on Control Loop with TMIN and TRANGE Values
PWM Duty Cycle
00
0%
01
7%
02
14%
03
20%
04
27%
05
33% Recommended
06
40%
07
47%
08
53%
09
60%
10 (0x0A)
67%
11 (0x0B)
73%
12 (0x0C)
= Temperature at which fan runs full speed
= Temperature at which fan will turn on
= Maximum Duty Cycle (100%) = 15 decimal
= Duty Cycle at TMIN, programmed into
Fan Speed Config Register
(default = 33% = 5 decimal)
= PWM Duty Cycle versus Temperature Slope
TRANGE
Example 1
TMIN
= 0C, TRANGE = 40C
Min DC = 53% = 8 decimal (Table 12)
Calculate TMAX
Table 12. PWM DUTY CYCLE SELECT MODE
Decimal Value
T RANGEń10) (eq. 6)
T MAX + T MIN ) ((Max DC * Min DC)
T RANGEń10)
T MAX + 0 ) ((100% DC * 53% DC)
40ń10)
T MAX + 0 ) ((15 * 8)
4) + 28
TMAX =285C. (As seen on Slope 2 of Figure 34)
Example 2
TMIN
= 0C, TRANGE = 40C
Min DC = 73% = 11 decimal (Table 12)
Calculate TMAX
T MAX + T MIN ) ((Max DC * Min DC)
T RANGEń10)
80%
T MAX + 0 ) ((100% DC * 73% DC)
40ń10)
87%
T MAX + 0 ) ((15 * 11)
14 (0x0E)
93%
15 (0x0F)
100% (Default)
TMAX =165C. (As seen on Slope 3 of Figure 34)
Example 3
TMIN
= 0C, TRANGE = 40C
Min DC = 33% = 5 decimal (Table 12)
Calculate TMAX
13 (0x0D)
(eq. 7)
* Bits <3:0> set the Minimum PWM duty cycle for Automatic Mode.
Bits <7:4> set the Alarm Speed PWM duty cycle.
Slope 1 of Figure 34 shows TMIN set to 0C and the
TRANGE chosen is 40C. In this case, the fan’s PWM duty
cycle will vary over the range 33% to 100%. The fan will run
full speed at 40C. If the minimum PWM duty cycle at which
the fan runs at TMIN is changed, its effect can be seen on
Slopes 2 and 3. Take Case 2, where the minimum PWM duty
cycle is reprogrammed from 33% (default) to 53%. The fan
T MAX + T MIN ) ((Max DC * Min DC)
T RANGEń10)
T MAX + 0 ) ((100% DC * 33% DC)
40ń10)
T MAX + 0 ) ((15 * 5)
4) + 40
TMAX =405C. (As seen on Slope 1 of Figure 34)
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(eq. 8)
4) + 16
(eq. 9)
ADM1029
TEMP COOLING ACTION (CONFIGURE REG 0X48 FOR LOCAL
TEMP, REG 0X49 FOR REMOTE 1 TEMP AND REG 0X4A FOR
REMOTE 2 TEMP)
PROGRAM FAN
MINIMUM DUTY CYCLE
FAN 1 (REG 0X60)
FAN 2 (REG 0X61)
CONFIGURE TEMP
COOLING ACTION
LOCAL TEMP (REG 0X48)
REMOTE 1 TEMP (REG 0X49)
REMOTE 2 TEMP (REG 0X4A)
OPTION 1
BIT 0 (REG 0X49) AND/OR BIT 1 (REG 0X4A) = 1
REMOTE 1 TEMP CONTROLS FAN 1
REMOTE 2 TEMP CONTROLS FAN 2
OPTION 2
BIT 0 (REG 0X48) AND BIT 1 (REG 0X48) = 1
LOCAL TEMP CONTROLS FAN 1 AND/OR FAN 2
OPTION 3
BIT 0 (REG 0X49) AND BIT 1 (REG 0X49) = 1
REMOTE 1 TEMP CONTROLS FAN 1 AND/OR FAN 2
OPTION 4
BIT 0 (REG 0X4A) AND BIT 1 (REG 0X4A) = 1
REMOTE 2 TEMP CONTROLS FAN 1 AND/OR FAN 2
OPTION 5
BIT 0, 1 (REG 0X48, 0X49, 0X4A) = 1
FAN 1 AND/OR FAN 2 RUNS AT FASTEST SPEED
CALCULATED BY ALL TEMPERATURE CHANNELS
PROGRAM FAN START
TEMPERATURE, TMIN
LOCAL TEMP (REG 0X80)
REMOTE 1 TEMP (REG 0X81)
REMOTE 2 TEMP (REG 0X82)
REMOTE 1
TEMPERATURE
PROGRAM TEMP-TO-FAN
SPEED CONTROL SLOPE,
TRANGE
FAN 1
FAN 1
ADM1029
ADM1029
LOCAL TEMP
LOCAL TEMP (REG 0X88)
REMOTE 1 TEMP (REG 0X89)
REMOTE 2 TEMP (REG 0X8A)
REMOTE 2
TEMPERATURE
CONFIGURE CONTROL
LOOP HYSTERESIS
LOCAL TEMP (REG 0X88)
REMOTE 1 TEMP (REG 0X89)
REMOTE 2 TEMP (REG 0X8A)
OPTION 1
FAN 2
REMOTE 1
TEMPERATURE
CONFIGURE FAN
SPIN-UP TIME
FAN 1
OPTION 2
FAN 2
REMOTE 1
TEMPERATURE
ADM1029
FAN 1
ADM1029
(REGISTER 0X0C)
CONFIGURE PWM DRIVE
FREQUENCY
FAN 1 (REG 0X68)
FAN 2 (REG 0X69)
REMOTE 2
TEMPERATURE
REMOTE 2
TEMPERATURE
OPTION 3
FAN 2
REMOTE 1
TEMPERATURE
OPTION 4
FAN 2
FAN 1
CONFIGURE TACH
OSCILLATOR FREQUENCY
FAN 1 (REG 0X68)
FAN 2 (REG 0X69)
ADM1029
LOCAL TEMP
MEASURE
FAN SPEED
FAN 1 (REG 0X70)
FAN 2 (REG 0X71)
REMOTE 2
TEMPERATURE
OPTION 5
Figure 35. Configuring Automatic Fan Speed Control
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FAN 2
ADM1029
Table 13. RESISTOR RATIOS FOR SETTING TMIN AND NUMBER OF FANS INSTALLED USING TMIN/INSTALL PIN
(PIN 18)
3 MSBs of
ADC
Ideal Ratio
R2/(R1 + R2)
R1 (kW)
R2 (kW)
Actual
R2/(R1 + R2)
Error (%)
TMIN
Fans Installed
111
N/A
0

1
0
Disabled
2
110
0.8125
18
82
0.82
0.75
48C
2
101
0.6875
22
47
0.6812
−0.63
40C
2
100
0.5625
12
15
0.5556
−0.69
32C
2
011
0.4375
15
12
0.4444
0.69
32C
1
010
0.3125
47
22
0.3188
0.63
40C
1
001
0.1875
82
18
0.18
−0.75
48C
1
000
N/A

0
0
0
Disabled
1
Fan-related Registers
In this case, since the Minimum Duty Cycle is the default
33%, the equation for TMAX reduces to:
T MAX + T MIN ) ((Max DC * Min DC)
T MAX + T MIN ) ((15 * 5)
T MAX + T MIN ) (10
Table 14 is a list of registers on the ADM1029 that are
specific to fan speed measurement and control:
T RANGEń10)
T RANGEń10)
T RANGEń10)
Table 14. TEMPERATURE-SPECIFIC REGISTERS
(eq. 10)
Address
T MAX + T MIN ) T RANGE
Enabling Automatic Fan Speed Control Using
TMIN/INSTALL Pin (Pin 18)
Automatic fan control can also be enabled in hardware by
Pin 18 (TMIN/INSTALL). This is an 8-level input with
multiple functions, which is sampled only at power-up.
If only one fan is installed, the voltage on Pin 18 should
be kept at less than VCC/2, which clears Bit 1 of register 03h.
Within this voltage range, four voltage levels define the
minimum temperature at which the fan will operate in
automatic speed control mode.
If two fans are installed, the voltage on Pin 18 should be
between VCC/2 and VCC, which sets Bit 1 of register 03h.
Within this voltage range, four voltage levels define the
minimum temperature at which the fans will operate in
automatic speed control mode.
Resistor values for setting the voltage on Pin 18 are given
in Table 13. If automatic fan speed control is not used,
Pin 18 can simply be strapped to ground (one fan) or VCC
(two fans), depending on how many fans are installed.
Under this condition, the fans will run full speed until the
device is written to by software to change fan speed.
When automatic fan speed control is enabled at power-up
by the TMIN/INSTALL pin, Bit 4 of the Configuration
register is set to enable monitoring, and Bits 0 and 1 of all
Temp. Cooling Action Registers are set, so any temperature
channel will automatically control all fans that are installed.
NOTE:
Description
0x02
Fans Supported By Controller
0x03
Fans Supported In System
0x07
Set Fan x Alarm Speed
0x08
Set Fan x Hot-Plug Speed
0x09
Set Fan x Full Speed
0x10
Fan 1 Status
0x11
Fan 2 Status
0x18
Fan 1 Fault Action
0x19
Fan 2 Fault Action
0x20
Fan 1 Event Mask
0x21
Fan 2 Event Mask
0x48
Local Temp Cooling Action
0x49
Remote 1 Cooling Action
0x4A
Remote 2 Cooling Action
0x60
Fan 1 Minimum/Alarm Speed
0x61
Fan 2 Minimum/Alarm Speed
0x68
Fan 1 Configuration
0x69
Fan 2 Configuration
0x70
Fan 1 Tach Value
0x71
Fan 2 Tach Value
0x78
Fan 1 Tach High Limit
0x79
Fan 2 Tach High Limit
Fan Configuration Registers
Registers 0x68 and 0x69 are the Fan 1 and Fan 2
Configuration Registers. These allow the PWM output
frequencies to be selected for each fan. The default PWM
drive frequency is 250 Hz. Bits <7:6> adjust the fan tach
oscillator frequency for fan tach measurements. Bits <3:0>
allow the Hot Plug PWM duty cycle value for each fan to be
programmed.
Figures 36 and 37 show how to configure the fans to
handle thermal or fault events.
if automatic fan speed control is enabled and an event
occurs that would cause a fan to go to alarm or hot-plug
speed (e.g., temperature fault), that event will override the
automatic fan speed control. If the event affects only one
fan, the other fan will remain under automatic control.
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ADM1029
FAN FAULT ACTION (CONFIGURE REG 0X18 FOR FAN 1, REG 0X19 FOR FAN 2)
SET FAN 1 = 33%
SET FAN 2 = 33%
DEFAULT
FAN 1 = 100%
FAN 2 = 100%
DEFAULT
FAN 1 = 100%
FAN 2 = 100%
CONFIGURE FAN
NORMAL SPEED
FAN 1 (REG 0X60)
FAN 2 (REG 0X61)
CONFIGURE FAN
ALARM SPEED
BIT 0 = 1
BIT 1 = 1
BIT 2 = 1
BIT 3 = 1
BIT 4 = 1
BIT 5 = 1
BIT 6 = 1
BIT 7 = 1
ASSERT CFAULT ON FAN FAULT (TACH FAILURE OR FAULT ASSERTION)
ASSERT INT ON FAN FAULT (TACH FAILURE OR FAULT ASSERTION)
ASSERT CFAULT IF FAN HOT UNPLUGGED
ASSERT INT IF FAN HOT UNPLUGGED
THERMAL OVERRIDE IF IN SLEEP MODE (FAN RUNS AT ALARM SPEED)
DRIVE FAULT LOW IF A FAN FAULT IS DETECTED
IF CFAULT PULLED LOW EXTERNALLY, RUN FAN AT HOT-PLUG SPEED
IF CFAULT PULLED LOW ESTERNALLY, RUN FAN AT ALLARM SPEED
7
6
5
4
3
2
1
FAN 1 (REG 0X60)
FAN 2 (REG 0X61)
0
FAN TACH
FAILURE OR
FAULT PIN
LOW?
FAN TACH
FAILURE OR
FAULT PIN
LOW?
CONFIGURE FAN
HOT-PLUG SPEED
FAN 1 (REG 0X68)
FAN 2 (REG 0X69)
HAS A FAN
BEEN HOT
UNPLUGGED?
CONFIGURE FAN FAULT
ACTION
HAS A FAN
BEEN HOT
UNPLUGGED?
FAN 1 (REG 0X18)
FAN 2 (REG 0X19)
OVERTEMPERATURE
DETECTED IN
SLEEP MODE?
CONFIGURE FAN FAULT
MASK REGISTERS
FAN TACH
FAILURE OR
FAULT PIN
LOW?
FAN 1 (REG 0X20)
FAN 2 (REG 0X21)
HAS CFAULT
BEEN PULLED
LOW?
HAS CFAULT
BEEN PULLED
LOW?
CFAULT
YES
INT
YES
CFAULT
YES
INT
YES
FAN RUNS AT ALARM SPEED
YES
YES
FAN RUNS AT HOT-PLUG SPEED
YES
FAN RUNS AT ALARM SPEED
YES
FAN TACH
FAILURE OR
FAULT PIN
LOW?
BIT 0 = 1
RUN FAN 1 AT ALARM SPEED
IF FAN FAULT IS DETECTED
BIT 1 = 1
RUN FAN 2 AT ALARM SPEED
IF FAN FAULT IS DETECTED
BIT 2 − 7
DON’T CARE
FAN FAULT MASK (CONFIGURE REG 0X20 FOR
FAN 1, REG 0X21 FOR FAN 2)
Figure 36. Fan Configuration Flowchart
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FAN TACH
FAILURE OR
FAULT PIN
LOW?
FAN 1 RUNS ALARM SPEED
YES
FAN 2 RUNS ALARM SPEED
YES
ADM1029
GPIO EVENT MASK (CONFIGURE REG 0X38
FOR GPIO0, REG 0X39 FOR GPIO1…REG 0X3E
FOR GPIO6)
BIT 0 = 1
FAN 1 RUNS AT ALARM OR
HOT-PLUG SPEED IF GPIO PIN
IS ASSERTED
BIT 1 = 1
FAN 2 RUNS AT ALARM OR
HOT-PLUG SPEED IF GPIO PIN
IS ASSERTED
BIT 2−7
DON’T CARE
IS GPIO PIN
ASSERTED?
YES
FAN RUNS AT ALARM
OR HOT-PLUG SPEED
CONFIGURE GPIO EVENT
MASK REGISTERS
(REG 0X38 − 0X3E)
CONFIGURE TEMP
COOLING ACTION
PROGRAM FAN START
TEMPERATURE, TMIN
LOCAL TEMP (REG 0X80)
REMOTE 1 TEMP (REG 0X81)
REMOTE 2 TEMP (REG 0X82)
LOCAL TEMP (REG 0X48)
REMOTE 1 TEMP (REG 0X49)
REMOTE 2 TEMP (REG 0X4A)
CONFIGURE AIN EVENT
MASK REGISTERS
PROGRAM TEMP-TO-FAN
SPEED CONTROL SLOPE,
TRANGE
LOCAL TEMP (REG 0X88)
REMOTE 1 TEMP (REG 0X89)
REMOTE 2 TEMP (REG 0X8A)
AUTOMATIC FAN
SPEED CONTROL
CONFIGURATION
(REFER TO AUTOMATIC FAN SPEED
CONTROL FLOWCHART)
AIN1 (REG 0X58)
AIN2 (REG 0X59)
CONFIGURE CONTROL
LOOP HYSTERESIS
CONFIGURE FAN
SPIN-UP TIME
LOCAL TEMP (REG 0X88)
REMOTE 1 TEMP (REG 0X89)
REMOTE 2 TEMP (REG 0X8A)
REGISTER 0X0C
CONFIGURE PWM DRIVE
FREQUENCY
FAN 1 (REG 0X68)
FAN 2 (REG 0X69)
CONFIGURE TACH
OSCILLATOR FREQUENCY
AIN EVENT MASK (CONFIGURE REG 0X58 FOR AIN 0,
REG 0X59 FOR AIN 1)
BIT 0 = 1
FAN 1 RUNS AT ALARM SPEED
IF AIN OUT-OF-LIMIT EVENT OCCURS
BIT 1 = 1
FAN 2 RUNS AT ALARM SPEED
IF AIN OUT-OF-LIMIT EVENT OCCURS
BIT 2 − 7
DON’T CARE
IS AIN PIN
ASSERTED?
FAN 1 (REG 0X68)
FAN 2 (REG 0X69)
MEASURE
FAN SPEED
FAN 1 (REG 0X70)
FAN 2 (REG 0X71)
Figure 37. Fan Configuration Flowchart (Continued)
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YES
FAN RUNS AT ALARM
OR HOT-PLUG SPEED
ADM1029
Reset Input
Pin 12 is an active-low system RESET input. Taking this
pin low will generate a system reset, which will reset all
registers to their default values.

Analog Inputs
Pins 19 and 20 of the ADM1029 are dual-function pins.
They may be configured as general-purpose logic I/O pins
by setting Bits 0, 1 of the GPIO Present/AIN Register
(address 05h) or as 0 V to 2.5 V analog inputs by clearing
these bits.
In the analog input mode, Pins 19 and 20 have an input
range of 0 V to 2.5 V. By suitable input scaling, the analog
input may be configured to measure other voltage ranges
such as system power supply voltages. If more than one
ADM1029 is used in a system, several such voltages may be
monitored.
The measured values of AIN0 and AIN1 are stored in the
AIN0 and AIN1 Value Registers (addresses B8h and B9h)
and are compared to high and low limits stored in the AIN0
and AIN1 High and Low Limit Registers (addresses A8h,
A9h and B0h, B1h).
The response of the ADM1029 to an out-of-limit
measurement on AIN0 or AIN1 depends on the status of the
AIN0 and AIN1 Behavior Registers (Registers 50h, 51h).
The response of CFAULT, INT, and fan speed to temperature
events depends on the setting of these registers, as detailed
in the register tables later in this data sheet. Figure 38 shows
how the AIN pins can be configured to respond to different
events.




INT will be asserted if the corresponding temperature
high limit is exceeded
If Bit 6 of a Temp. Fault Action Register is set, INT
will be asserted if a temperature input crosses the
corresponding temperature low limit, the direction
depending on the setting of Bit 3 of the Temp. Fault
Action register. (0 = INT when temperature goes below
low limit, 1 = INT when temperature goes above low
limit)
If Bit 1 of a Fan Fault Action Register (18h or 19h) is
set, INT will be asserted when a tach measurement for
the corresponding fan exceeds the set limit
If Bit 1 of a Fan Fault Action Register (18h or 19h) is
set, INT will be asserted when the fan fault input pin
for the corresponding fan is asserted (low)
If Bit 2 of an AIN Behavior Register is set
(50h − AIN0, 51h − AIN1), INT will be asserted if the
corresponding AIN high limit is exceeded
If Bit 6 of an AIN Behavior Register is set, INT will be
asserted if the corresponding analog input crosses its
AIN low limit, the direction depending on the setting of
Bit 3 of the AIN Behavior register. (0 = INT when input
goes below low limit, 1 = INT when input goes above
low limit)
Fan Free-Wheeling Test
The Fan Free-Wheeling Test is used to diagnose fans
connected to the ADM1029 to ensure that they are operating
correctly. Large fans tightly coupled in a duct can affect each
other’s airflow. If one fan has failed it may not be apparent,
as the other fan moving can suck air through the faulty fan
causing it to spin. The ADM1029 will spin each fan up
separately with the other powered down and measure the fan
speed of both. When it tries to spin the failed fan with the
working fan off, the fan speed measurement will fail, and the
faulty fan will be detected. The Fan Free-Wheel Test can be
invoked at any time in software by setting Bit 3 of the
Configuration Register (Reg. 0x01). The Fan Free-Wheel
Test normally takes about 10 seconds. Once the Fan
Free-Wheel test has completed, Bit 3 will automatically
clear to 0.
Analog Monitoring Cycle
The ADM1029 performs a sequential “round-robin,”
monitoring cycle on all analog inputs and temperature inputs
that are enabled. A conversion on AIN0 or AIN1 typically
takes 11.6 ms, while an external temperature conversion
takes 185.6 ms.
Interrupt (INT) Output
The INT output is an open-drain output with selectable
polarity, intended to communicate fault conditions to the
host processor. The polarity is set to active low by clearing
Bit 7 of the Configuration Register (address 01h) or to active
high by setting this bit.
INT can be asserted if any of the following conditions
occur:
 A hot-plug event
 Setting Bit 6 of the Configuration Register
(address 01h) forces INT to be asserted
 When a GPIO pin is configured as an input by setting
Bit 0 of the corresponding GPIO Behavior Register and
Bit 3 of the GPIO Behavior Register is also set, INT
will be asserted when the logic input is asserted (high
or low, depending on the polarity bit, Bit 1 of the
corresponding GPIO Behavior Register)
 If Bit 2 of a Temp. Fault Action Register is set
(40h − Local Sensor, 41h − Remote 1, 42h − Remote 2),
Automatic Fan Free-Wheel Test
Whenever a fan is hot-plugged, the Fan Free-Wheel Test
is automatically invoked. Bit 3 gets set high automatically
and once the test has completed, self-clears to 0. If 2 fans are
installed in the system, the Fan Free-Wheel Test is invoked
by removing the suspect fan and hotplugging a new one.
When the suspect fan (e.g., Fan 1) is removed, the Missing
bit (Bit 0) and Missing Latch bit (Bit 1) of the Fan 1 Status
Register are set. Fan 2 will then automatically run at
HotPlug Speed. If the faulty fan is replaced, the HotPlug
Latch bit (Bit 7) is set and the Missing bit (Bit 0) self-clears.
(However, the Missing Latch bit remains set.) Fan 2 will
return to its previous value automatically and the Fan
Free-Wheel Test is invoked. Fan 1 is run at 100% while
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ADM1029
before a subsequent Fan Free-Wheel Test can occur.
Otherwise, subsequent fan removals and insertions are
ignored.
Fan 2 is turned off. Fan 2 is then run at 100% with Fan 1
turned off. Both fans are then spun-up for the Fan Spin-up
time. Note that the Hotplug Latch bit and Missing Latch bit
remains set (Bits 7 and 1). These need to be cleared to 0
ENABLE PINS FOR AIN
FUNCTION
(REGISTER 0X05)
AIN PINS ENABLE (REG 0X05)
BIT 0 = 0
BIT 1 = 0
BITS 2−7
PIN 19 CONFIGURATED AS AIN0
PIN 20 CONFIGURATED AS AIN1
RESERVED FOR OTHER FUNCITIONS
AIN PINS BEHAVIOR (REG 0X50 CONFIGURES AIN0, REG 0X51 CONFIGURES AIN1)
CONFIGURE AIN PINS
BEHAVIOR
AIN0 (REG 0X50)
AIN1 (REG 0X51)
BIT 0 = 0
BIT 1 = 1
BIT 2 = 1
BIT 3 = 0
BIT 3 = 1
BIT 4 = 1
BIT 5 = 1
BIT 6 = 1
CONFIGURE AIN EVENT
MASK
BIT 7 = 1
AIN0 (REG 0X58)
AIN1 (REG 0X59)
7
CFAULT ASSERTED IF AIN VALUE EXCEEDS AIN HIGH LIMIT
FANS RUN ALARM SPEED IF AIN VALUE EXCEEDS AIN HIGH LIMIT
INT ASSERTED IF AIN VALUE EXCEEDS AIN HIGH LIMIT
ALARM GENERATED (INT, CFAULT, OR ALARM SPEED) WHEN AIN GOES BELOW AIN LOW LIMIT
ALARM GENERATED (INT, CFAULT, OR ALARM SPEED) WHEN AIN GOES ABOVE AIN LOW LIMIT
CFAULT ASSERTED IF AIN VALUE EXCEEDS AIN LOW LIMIT. BIT 3 DECIDES WHETHER CFAULT
IS ASSERTED GOING ABOVE OR BELOW THE LOW LIMIT
FANS RUN ALARM SPEED IF AIN VALUE CROSSES THE AIN LOW LIMIT. BIT 3 DECIDES WHETHER
ALARM SPEED IS TRIGGERED GOING ABOVE OR BELOW THE LOW LIMIT
INT ASSERTED IF AIN VALUE CROSSES THE AIN LOW LIMIT. BIT 3 DECIDES WHETHER INT IS
ASSERTED GOING ABOVE OR BELOW THE LOW LIMIT
THIS BIT LATCHES AN OUT-OF-LIMIT AIN EVENT. CLEARED BY WRITING A ’0’
6
5
4
3
2
1
0
AIN EVENT MASK
(CONFIGURE REG 0X58 FOR
AIN0, REG 0X59 FOR AIN1)
BIT 0 = 1
RUN FAN 1 AT ALARM SPEED IF AIN
OUT-OF-LIMIT EVENT IS DETECTED
BIT 1 = 1
RUN FAN 2 AT ALARM SPEED IF AIN
OUT-OF-LIMIT EVENT IS DETECTED
BITS 2−7
IS AIN
VALUE >
AIN HIGH
LIMIT?
IS AIN
VALUE >
AIN HIGH
LIMIT?
RESERVED − READ BACK ZERO
CONFIGURE AIN
HIGH LIMITS
IS AIN
VALUE >
AIN HIGH
LIMIT?
AIN0 (REG 0XA8)
AIN1 (REG 0XA9)
YES
CFAULT
YES
FANS RUN ALARM SPEED
YES
INT
AIN ABOVE OR
BELOW LOW AIN
LIMIT?
CONFIGURE AIN
LOW LIMITS
0 = ALARM BELOW AIN LOW LIMIT
1 = ALARM ABOVE AIN LOW LIMIT
HAS AIN
VALUE EXCEEDED
AIN LOW
LIMIT?
AIN0 (REG 0XB0)
AIN1 (REG 0XB1)
YES
CFAULT
HAS AIN
VALUE EXCEEDED
AIN LOW
LIMIT?
MEASURE AIN
VOLTAGES
AIN0 (REG 0XB8)
AIN1 (REG 0XB9)
YES
FANS RUN ALARM SPEED
HAS AIN
VALUE EXCEEDED
AIN LOW
LIMIT?
YES
INT
YES
Figure 38. Configuring AIN0 and AIN1 Pins
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ADM1029
General Purpose Logic Input/Outputs
CFAULT Output
The ADM1029 has six dual-function pins (see Pin
Function Descriptions section) that may be configured as
general-purpose Logic I/O pins by setting the appropriate
bit(s) of the GPIO Present/AIN Register (address 05h) or as
their alternate functions by clearing these bits.
When configured as GPIO pins, each GPIO pin has a
Behavior Register associated with it (Registers 28h to 2Eh)
that may be used to configure the operation of the pin.
The GPIO pins may be configured as inputs or outputs.
When used as inputs, they may be configured to:
 Be Active High or Active Low
 Set/Clear a Bit in the Behavior Register when GP Input
Is Asserted/Deasserted
 Latch a Bit In the Behavior Register when GP Input Is
Asserted (Must Be Cleared by Software)
 Assert CFAULT when GP Input Asserted
 Assert INT when GP Input Asserted
 Set Fan(s) to Alarm Speed when GP Input Asserted
 Set Fan(s) to Hot-plug Speed when GP Input Asserted
The Cascade Fault output (CFAULT), is an open-drain,
active low output, intended to communicate fault conditions
to other ADM1029s in a system, without the intervention of
the host processor. The other ADM1029’s may then adjust
their fans’ speed to compensate, depending on the settings
of various registers.
CFAULT is asserted if any of the following conditions
occurs:
 A Hot-plug Event
 Setting Bit 5 of the Configuration Register (Address
01h) forces CFAULT to be asserted
 When a GPIO pin is configured as an input by setting
Bit 0 of the corresponding GPIO Behavior Register and
Bit 2 of the GPIO Behavior Register is also set,
CFAULT will be asserted when the logic input is
asserted (high or low depending on the polarity bit,
Bit 1 of the corresponding GPIO Behavior Register)
 If Bit 0 of a Temp. Fault Action Register is set
(40h − Local Sensor, 41h − Remote 1, 42h − Remote 2),
CFAULT will be asserted if the corresponding
temperature high limit is exceeded
 If Bit 4 of a Temp. Fault Action Register is set,
CFAULT will be asserted if a temperature input crosses
the corresponding temperature low limit, the direction
depending on the setting of Bit 3 of the Temp. Fault
Action Register. (0 = CFAULT when input goes below
low limit, 1 = CFAULT when input goes above low
limit)
 If Bit 0 of a Fan Fault Action Register (18h or 19h) is
set, CFAULT will be asserted when a tach measurement
for the corresponding fan exceeds the set limit
 If Bit 0 of a Fan Fault Action Register (18h or 19h) is
set, CFAULT will be asserted, when the fan fault input
pin for the corresponding fan is asserted (low)
 If Bit 0 of an AIN Behavior Register is set
(50h − AIN0, 51h − AIN1), CFAULT will be asserted if
the corresponding AIN high limit is exceeded
 If Bit 4 of an AIN Behavior Register is set, CFAULT
will be asserted if an analog input crosses the
corresponding AIN low limit, the direction depending
on the setting of Bit 3 of the AIN Behavior Register.
(0 = CFAULT when input goes below low limit,
1 = CFAULT when input goes above low limit).







When Used as Outputs, They May Be Configured to:
Be Active High or Low
Be Asserted If a High Temperature Limit Is Exceeded
Be Asserted If a Temperature Measurement Falls
Below a Low Limit
Be Asserted If a Fan Fault Is Detected
Be Asserted If a Fan Tach Limit Is Exceeded
Be Asserted If an AIN High Limit Is Exceeded
Be Asserted If an Analog Input Falls Below a Low
Limit
Figure 39 shows how to configure the GPIO pins to
handle different out-of-limit and fault events.
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ADM1029
GPIO PINS ENABLE (REG 0X05)
ENABLE PINS FOR GPIO
FUNCTION
(REGISTER 0X05)
CONFIGURE GPIO PINS
BEHAVIOR
BIT 0 = 1
BIT 1 = 1
BIT 2 = 1
BIT 3 = 1
BIT 4 = 1
BIT 5 = 1
BIT 6 = 1
BIT 7
PIN 19 CONFIGURATED AS GPIO0
PIN 20 CONFIGURATED AS GPIO1
PIN 11 CONFIGURATED AS GPIO2
PIN 13 CONFIGURATED AS GPIO3
PIN 14 CONFIGURATED AS GPIO4
PIN 16 CONFIGURATED AS GPIO5
PIN 17 CONFIGURATED AS GPIO6
RESERVED
GPIO PINS BEHAVIOR (REG 0X28 CONFIGURES GPIO0, REG 0X29 CONFIGURES GPIO1, ETC.)
BIT 0
GPIO0 (REG 0X28)
BIT 1
GPIO6 (REG 0X2E)
BIT 2 = 1
BIT 3 = 1
CONFIGURE GPIO EVENT
MASK
BIT 4 = 1
GPIO0 (REG 0X38)
BIT 5 = 1
GPIO6 (REG 0X3E)
BIT 6 = 1
BIT 7
SETS THE DIRECTION FOR GPIO PIN. A ’A’ CONFIGURES THE PIN AS AN OUTPUT, A ’1’ SETS
THE PIN UP AS AN INPUT
SETS THE POLARITY FOR GPIO PIN. A ’0’ MAKES THE PIN ACTIVE LOW, A ’1’ MAKES THE PIN
ACTIVE HIGH
IF GPIO PIN IS CONFIGURED AS AN INPUT, CFAULT IS ASSERTED WHEN GPIO IS ASSERTED.
IF GPIO PIN IS CONFIGURED AS AN OUTPUT, GPIO PIN WILL BE ASSERTED IF A HIGH
TEMPERATURE LIMIT IS EXCEEDED. THIS CAN BE USED TO SHUT DOWN THE SYSTEM IN AN
OVER-TEMPERATURE SITUATION
IF GPIO PIN IS CONFIGURED AS AN INPUT, INT IS ASSERTED WHEN GPIO IS ASSERTED. IF GPIO
PIN IS AN OUTPUT, GPIO IS ASSERTED IF A TEMPERATURE LOW LIMIT IS EXCEEDED.
IF GPIO PIN IS CONFIGURED AS AN INPUT, FANS GO TO ALARM SPEED IF GPIO SI ASSERTED.
IF GPIO PIN SI AN OUTPUT, GPIO IS ASSERTED IF A FAN GO TO HOT-PLUG SPEED IF GPIO IS
ASSERTED.
IF GPIO PIN IS CONFIGURED AS AN INPUT, FANS GO TO HOT-PLUG SPEED IF GPIO IS ASSERTED.
IF GPIO PIN IS AN OUTPUT, GPIO IS ASSERTED IF A FAN FAULT IS DETECTED (FAULT PIN)
IF GPIO PIN SI AN INPUT, THIS BIT REFLECTS THE STATE OF GPIO PIN. IF GPIO PIN IS AN OUTPUT,
GPIO IS ASSERTED IF AN AIN HIGH LIMIT IS EXCEEDED
IF GPIO PIN SI AN INPUT, THIS BIT LATCHES A GPIO ASSERTION EVENT. CLEARED BY WRITING
A ’0’. IF GPIO PIN IS AN INPUT, GPIO IS ASSERTED IF AN AIN LOW LIMIT IS EXCEEDED
BIT 0 = 1
RUN FAN 1 AT ALARM OR HOT-PLUG SPEED IF GPIO PIN IS ASSERTED
BIT 1 = 1
RUN FAN 2 AT ALARM OR HOT-PLUG SPEED IF GPIO PIN IS ASSERTED
BIT 2−7
RESERVED − READ BACK ZERO
GPIO EVENT MASK (CONFIGURE REG 0X38 FOR GPIO0, REG 0X39 FOR GPIO1…REG 0X3E
FOR GPIO6)
Figure 39. Configuring GPIO Pins
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IS GPIO
PIN ASSERTED?
IS GPIO
PIN ASSERTED?
FAN 1 RUNS AT ALARM
OR HOT-PLUG SPEED
YES
FAN 2 RUNS AT ALARM
OR HOT-PLUG SPEED
YES
ADM1029
Table 15. REGISTER MAP
Address
Name
Default Value
00
Status Register
00h
01
Config Register
0000 0000
02
Fan Supported By Controller
03
Fans Supported In System
04
GPIOs Supported By Controller
05
Description
Contains the status of various fault conditions.
Configures the operation of the device.
03h
Contains the number of fans the device can support.
0000 00?1
Contains the number of fans actually supported by the device
in the application.
7Fh
Contains the number of GPIO pins the device can support.
GPIO Present/AIN
0????111
Used to configure GPIO pins as GPIO or as their alternate
analog input function.
06
Temp Devices Installed
0000 0??1
Contains number of temperature sensors installed.
07
Set Fan x Alarm Speed
00h
Writing to appropriate bit(s) makes fan(s) run at alarm speed.
08
Set Fan x Hot-plug Speed
00h
Writing to appropriate bit(s) makes fan(s) run at hot-plug
speed.
09
Set Fan x Full Speed
00h
Writing to appropriate bit(s) makes fan(s) run at full speed.
0B
S/W RESET
00h
Writing A6h to this register causes a software reset.
0C
Fan Spin-up
03h
Configures fan spin-up time.
0D
Manufacturer’s ID
41h
This register contains the manufacturer’s ID code for the
device.
0E
Major/Minor Revision
00h
Contains the manufacturer’s code for major and minor
revisions to the device in two nibbles.
0F
Manufacturer’s Test Register
00h
This register is used by the manufacturer for test purposes. It
should not be read from or written to in normal operation.
10
Fan 1 Status
0000 0?0?
Contains status information for Fan 1.
11
Fan 2 Status
0000 0?0?
Contains status information for Fan 2.
18
Fan 1 Fault Action
BFh
Sets operation of INT, CFAULT, etc., for Fan 1 fault.
19
Fan 2 Fault Action
BFh
Sets operation of INT, CFAULT, etc., for Fan 2 fault.
20
Fan 1 Event Mask
FFh
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to a fault or hot-plug event on Fan 1.
21
Fan 2 Event Mask
FFh
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to a fault or hot-plug event on Fan 2.
28
GPIO0 Behavior
00h
Configures the operation of GPIO0.
29
GPIO1 Behavior
00h
Configures the operation of GPIO1.
2A
GPIO2 Behavior
00h
Configures the operation of GPIO2.
2B
GPIO3 Behavior
00h
Configures the operation of GPIO3.
2C
GPIO4 Behavior
00h
Configures the operation of GPIO4.
2D
GPIO5 Behavior
00h
Configures the operation of GPIO5.
2E
GPIO6 Behavior
00h
Configures the operation of GPIO6.
30
Local Temperature Offset
00h
Offset register for local temperature measurement. The value
in this register is added to the local temperature value to
reduce system offset effects.
31
Remote 1 Temperature Offset
00h
Offset register for first remote temperature channel (D1). The
value in this register is added to the temperature value to
reduce system offset effects.
32
Remote 2 Temperature Offset
00h
Offset register for second remote temperature channel (D2).
The value in this register is added to the temperature value to
reduce system offset effects.
38
GPIO0 Event Mask
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to GPIO0 being asserted.
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ADM1029
Table 15. REGISTER MAP
Address
Name
Default Value
Description
39
GPIO1 Event Mask
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to GPIO1 being asserted.
3A
GPIO2 Event Mask
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to GPIO2 being asserted.
3B
GPIO3 Event Mask
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to GPIO3 being asserted.
3C
GPIO4 Event Mask
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to GPIO4 being asserted.
3D
GPIO5 Event Mask
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to GPIO5 being asserted.
3E
GPIO6 Event Mask
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to GPIO6 being asserted.
40
Local Temp Fault Action
08h
Configures the operation of INT, CFAULT, etc. for a Local
Temp fault (internal temperature sensor).
41
Remote 1 Temp Fault Action
08h
Configures the operation of INT, CFAULT, etc. for a Remote 1
Temp fault (D1 Temperature Sensor).
42
Remote 2 Temp Fault Action
08h
Configures the operation of INT, CFAULT, etc. for a Remote 2
Temp fault (D2 Temperature Sensor).
48
Local Temp Cooling Action
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to a Local Temp event (internal temperature sensor).
49
Remote 1 Temp Cooling Action
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to a Remote 1 Temp event (D1 temperature sensor).
4A
Remote 2 Temp Cooling Action
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to a Remote 2 Temp event (D2 temperature sensor).
50
AIN0 Behavior
00h
Configures the operation of INT, CFAULT, etc. for a fault on
Analog Channel 0.
51
AIN1 Behavior
00h
Configures the operation of INT, CFAULT, etc. for a fault on
Analog Channel 1.
58
AIN0 Event Mask
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to a fault on Channel 0.
59
AIN1 Event Mask
00h
Enables/disables Fan 1 and/or Fan 2 alarm/hot-plug speed in
response to a fault on Channel 1.
60
Fan 1 Minimum/Alarm Speed
FFh
Contains the Minimum/Alarm speeds for Fan 1.
61
Fan 2 Minimum/Alarm Speed
FFh
Contains the Minimum/Alarm speeds for Fan 2.
68
Fan 1 Configuration
2Fh
Configures hot-plug speed, PWM and tach frequency.
69
Fan 2 Configuration
2Fh
Configures hot-plug speed, PWM and tach frequency.
70
Fan 1 Tach Value
00h
Contains the measured value from the Fan 1 tachometer
output.
71
Fan 2 Tach Value
00h
Contains the measured value from the Fan 2 tachometer
output.
78
Fan 1 Tach High Limit
FFh
Contains the high limit for Fan 1 tachometer measurement.
79
Fan 2 Tach High Limit
FFh
Contains the high limit for Fan 2 tachometer measurement.
80
Local Temp TMIN
??h
Defines the starting temperature for the fan when controlled by
the local temperature channel, under Automatic Fan Speed
Control.
81
Remote 1 Temp TMIN
??h
Defines the starting temperature for the fan when controlled by
the Remote 1 temperature channel, under Automatic Fan
Speed Control. (D1 Temp Sensor).
82
Remote 2 Temp TMIN
??h
Defines the starting temperature for the fan when controlled by
the Remote 2 temperature channel, under Automatic Fan
Speed Control. (D2 Temp Sensor).
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ADM1029
Table 15. REGISTER MAP
Address
Name
Default Value
Description
88
Local Temp TRANGE/THYST
51h
This register programs the control range for the local
temperature control loop. It also defines the amount of
temperature hysteresis applied to the loop.
89
Remote 1 Temp TRANGE/THYST
51h
This register programs the control range for the Remote 1
temperature control loop. It also defines the amount of
temperature hysteresis applied to the loop.
8A
Remote 2 Temp TRANGE/THYST
51h
This register programs the control range for the Remote 2
temperature control loop. It also defines the amount of
temperature hysteresis applied to the loop.
90
Local Temp High Limit
50h (80C)
High limit for Local measurement (internal sensor).
91
Remote 1 Temp High Limit
64h (100C)
High limit for Remote 1 measurement (D1 Sensor).
92
Remote 2 Temp High Limit
64h (100C)
High limit for Remote 2 measurement (D2 Sensor).
98
Local Temp Low Limit
3Ch (60C)
Low limit for Local Temp measurement (internal sensor).
99
Remote 1 Temp Low Limit
46h (70C)
Low limit for Remote 1 measurement (D1 Sensor).
9A
Remote 2 Temp Low Limit
46h (70C)
Low limit for Remote 2 measurement (D2 Sensor).
A0
Local Temp Value
00h
Measured value from local temp sensor.
A1
Remote 1 Temp Value
00h
Measured value from D1 Remote Sensor.
A2
Remote 2 Temp Value
00h
Measured value from D2 Remote Sensor.
A8
AIN0 High Limit
FFh
High limit for measurement on analog Channel 0.
A9
AIN1 High Limit
FFh
High limit for measurement on analog Channel 1.
B0
AIN0 Low Limit
00h
Low limit for measurement on analog Channel 0.
B1
AIN1 Low Limit
00h
Low limit for measurement on analog Channel 1.
B8
AIN0 Measured Value
00h
Measured value of analog Channel 0.
B9
AIN1 Measured Value
00h
Measured value of analog Channel 1.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
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ADM1029
CONFIGURATION REGISTERS
Table 16. REGISTER 01H − CONFIG REGISTER (POWER-ON DEFAULT 000? 000?)
Bit
Name
R/W
Description
0
Install = ?
R/W
This bit reflects Bit 1 of Register 0x03 (Fans Supported In System).
1
Global INT mask = 0
R/W
Setting this bit to 1 will disable the INT output for all interrupt sources.
2
ARA Disable = 0
R/W
Setting this bit to 1 will disable the SMBus Alert Response Address
feature.
3
Perform Free-Wheel Test = 0
R/W
Setting this bit to 1 will initiate the Fan Free-Wheeling Test. While this test
is being performed normal monitoring of fan speeds, temperature and
voltages will be temporarily halted. This bit will automatically reset to 0
once the test is complete which will take about 10 seconds.
4
Start Monitoring = 0
R/W
Set to 1 to start round robin monitoring cycle of voltage temperature and
fan speeds, fault detection, etc. While this bit is 0, all fans will run at Alarm
Speed. This bit is set at power-up; otherwise, if automatic fan speed
control is enabled by Pin 18.
5
Force CFAULT = 0
R/W
Setting this bit to 1 forces CFAULT to be asserted (Low).
6
Force INT = 0
R/W
Setting this bit to 1 forces INT to be asserted (Polarity depends on Bit 7).
7
INT Polarity = 0
R/W
Polarity of INT when asserted. 1 means High and 0 means Low.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
Table 17. REGISTER 05H – GPIO PRESENT/AIN (POWER-ON DEFAULT 0????111)
Bit
Name
R/W
Description
0
GPIO 0 = 1
R/W
Indicates that GPIO0 is being used. Set to 1 on power-up, but can be
overwritten by software. Setting this bit to 0 means AIN0 is being used.
1
GPIO 1 = 1
R/W
Indicates that GPIO1 is being used. Set to 1 on power-up, but can be
overwritten by software. Setting this bit to 0 means AIN1 is being used.
2
GPIO 2 = 1
R/W
Indicates that GPIO2 is being used. Set to 1 on power-up, but can be
overwritten by software.
3
GPIO 3 = ?
R/W
Indicates that GPIO3 is being used. Setting this bit to 0 means TDM1 is
being used. The ADM1029 can detect on power-up if TDM1 is connected.
If so, this bit is set to 0, otherwise it is set to 1. The default setting can be
overwritten by software.
4
GPIO 4 = ?
R/W
Indicates that GPIO4 is being used. Setting this bit to 0 means TDM1 is
being used. The ADM1029 can detect on power-up if TDM1 is connected.
If so, this bit is set to 0, otherwise it is set to 1. The default setting can be
overwritten by software.
5
GPIO 5 = ?
R/W
Indicates that GPIO5 is being used. Setting this bit to 0 means TDM2 is
being used. The ADM1029 can detect on power-up if TDM2 is connected.
If so, this bit is set to 0, otherwise it is set to 1. The default setting can be
overwritten by software.
6
GPIO 6 = ?
R/W
Indicates that GPIO6 is being used. Setting this bit to 0 means TDM2 is
being used. The ADM1029 can detect on power-up if TDM2 is connected.
If so, this bit is set to 0, otherwise it is set to 1. The default setting can be
overwritten by software.
7
Reserved
R
Unused. Will read back 0.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
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ADM1029
Table 18. REGISTER 07H – SET FAN X* ALARM SPEED (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Fan 1 Alarm Speed = 0
R/W
When set to 1, Fan 1 will run at Alarm Speed.
1
Fan 2 Alarm Speed = 0
R/W
When set to 1, Fan 2 will run at Alarm Speed.
2
Reserved
R
Unused. Will read back 0.
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
* “x” denotes the fan number.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
Table 19. REGISTER 08H – SET FAN X* HOT-PLUG SPEED (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Fan 1 Hot-Plug Speed = 0
R/W
When set to 1, Fan 1 will run at Hot-Plug Speed.
1
Fan 2 Hot-Plug Speed = 0
R/W
When set to 1, Fan 2 will run at Hot-Plug Speed.
2
0
R
Unused. Will read back 0.
3
0
R
Unused. Will read back 0.
4
0
R
Unused. Will read back 0.
5
0
R
Unused. Will read back 0.
6
0
R
Unused. Will read back 0.
7
0
R
Unused. Will read back 0.
* “x” denotes the fan number.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
Table 20. REGISTER 09H – SET FAN X* FULL SPEED (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Fan 1 Full Speed = 0
R/W
When set to 1 Fan 1 will run at Full Speed.
1
Fan 2 Full Speed = 0
R/W
When set to 1 Fan 2 will run at Full Speed.
2
Reserved
R
Unused. Will read back 0.
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
* “x” denotes the fan number.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
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ADM1029
STATUS REGISTERS
Table 21. REGISTER 00H – STATUS REGISTER (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
This bit is set to 1 when the device is asserting INT low. This bit is the
logical OR of several bits in other registers and is cleared when these bits
are cleared.
0
INT
R
1
CFAULT_in
R
2
CFAULT_out
R
This bit is set to 1 when the device is asserting CFAULT low. This bit is the
logical OR of several bits in other registers and is cleared when these bits
are cleared.
3
In Alarm_speed
R
This bit is set to 1 when either fan is running at Alarm Speed. This bit is
the logical OR of several bits in other registers and is cleared when these
bits are cleared.
4
In Hot-Plug Speed
R
This bit is set to 1 when either fan is running at Hot-Plug Speed. This bit is
the logical OR of several bits in other registers and is cleared when these
bits are cleared.
5
GPIO/AIN Event
R
This bit is a logical OR of Bits 1, 3, 6, and 7 in the GPIO Behavior
Registers at 28h to 2Eh while they are configured as inputs, and Bit 7 in
the AIN Behavior Registers at 50h and 51h. It will be set when any of
these bits are set and cleared when all of these bits are cleared.
6
Hot Plug/Fan Fault
R
This bit is a logical OR of Bits 1, 3, 6, and 7 in the Fan Status Registers at
10h and 11h. It will be set when any of these bits are set and cleared
when all of these bits are cleared.
7
Thermal Event
R
This bit is a logical OR of Bit 7 in the Temp Fault Action Registers at 40h,
41h, and 42h. It will be set when any of these bits are set and cleared
when all of these bits are cleared.
This bit is set to 1 when the device is receiving CFAULT low from another
device.
Table 22. REGISTER 02H – FAN SUPPORTED BY CONTROLLER (POWER-ON DEFAULT 03H)
Bit
Name
R/W
Description
0
Fan 1 = 1
R
This bit set to 1 means the ADM1029 can support Fan 1.
1
Fan 2 = 1
R
This bit set to 1 means the ADM1029 can support Fan 2.
2
Reserved
R
Unused. Will read back 0.
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
Table 23. REGISTER 03H – FANS SUPPORTED IN SYSTEM (POWER-ON DEFAULT 0000 00?1)
Bit
Name
R/W
Description
0
Fan 1 = 1
R/W
Indicates that Fan 1 is being used. Set to 1 on Power-up, but can be overwritten by software.
1
Fan 2 = ?
R/W
Indicates that Fan 2 is being used. Set by Pin 18 (TMIN/INSTALL) on
Power-up, but can be overwritten by software.
2
Reserved
R
Unused. Will read back 0.
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
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ADM1029
Table 24. REGISTER 04H – GPIOS SUPPORTED BY CONTROLLER (POWER-ON DEFAULT 7FH)
Bit
Name
R/W
Description
0
GPIO 0 = 1 (Pin 19)
R
This bit set to 1 means the ADM1029 can support GPIO0, available on
Pin 19.
1
GPIO 1 = 1 (Pin 20)
R
This bit set to 1 means the ADM1029 can support GPIO1, available on
Pin 20.
2
GPIO 2 = 1 (Pin 11)
R
This bit set to 1 means the ADM1029 can support GPIO2, available on
Pin 11.
3
GPIO 3 = 1 (Pin 13)
R
This bit set to 1 means the ADM1029 can support GPIO3, available on
Pin 13.
4
GPIO 4 = 1 (Pin 14)
R
This bit set to 1 means the ADM1029 can support GPIO4, available on
Pin 14.
5
GPIO 5 = 1 (Pin 16)
R
This bit set to 1 means the ADM1029 can support GPIO5, available on
Pin 16.
6
GPIO 6 = 1 (Pin 17)
R
This bit set to 1 means the ADM1029 can support GPIO6, available on
Pin 17.
7
Reserved
R
Unused. Will read back 0.
Table 25. REGISTER 06H – TEMP DEVICES INSTALLED (POWER-ON DEFAULT 0000 0??1)
Bit
Name
R/W
Description
0
Local Temp = 1
R
This bit is permanently set to 1 since the local temperature sensor is always available.
1
Remote 1 Temp = ?
R
This bit is set to 1 if the Remote 1 temperature sensor (TDM1) is installed.
(Automatically detected on power-up.)
2
Remote 2 Temp = ?
R
This bit is set to 1 if the Remote 2 temperature sensor (TDM2) is installed.
(Automatically detected on power-up.)
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
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ADM1029
Table 26. REGISTER 10H, 11H – FAN X* STATUS (POWER-ON DEFAULT 0000 0?0?)
Bit
Name
0
Missing = x
1
Missing _L = 0
2
Fault_ = x
3
R/W
Description
R
Reflects the state of Pins 4/21. Low means Fan x* is installed, High
means it is missing. This bit will automatically return Low if a missing fan
is replaced.
R/W
This bit is edge-triggered and latches a Fan x* missing event on removal
of Fan x. This bit is cleared by writing a 0 to it.
R
Inverse of Pin 2/23. Low on pin means Fan x* has a fault (Pins 2/23 Low),
High on pin means it is OK. This bit will automatically return Low if Pins
2/23 goes high.
Fault_L_ = 0
R/W
This bit is edge-triggered and latches a Fan x* fault event on Pins 2/23.
This bit is cleared by writing a 0 to it. If the PRESENT pin for a fan input is
high (fan not installed) this bit will be cleared automatically.
4
Sleep = 0
R/W
When this bit is set, Fan x* will be stopped and no Fan x* faults will be
monitored. If Bit 4 in Fan x* Fault Action Register is set, Fan x* will go to
Alarm Speed if an overtemperature event is detected as per settings in the
Temp Fault Action Registers.
5
Hot Plug Priority
R/W
This bit indicates whether Fan x runs at Hot-Plug Speed (bit set to 1) or
Alarm Speed (bit set to 0) if both modes are triggered.
6
Tach_Fault_L
R/W
Latches a Fan x Tach Fault. This bit is cleared by writing a 0 to it. If the
PRESENT pin for a fan input is high (fan not installed), this bit will be
cleared automatically.
7
Hot_Plug_L
R/W
This bit is edge-triggered and latches a Fan x Hot-plug event which is the
insertion of Fan x. (Note difference to Bit 1.) This bit is cleared by writing a
0 to it. If a fan is Hot-plug installed, it will run at Normal Speed.
* “x” denotes the fan number. Register 10h is for Fan 1 and Register 11h is for Fan 2.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
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ADM1029
TEMPERATURE REGISTERS
Table 27. REGISTER 06H – TEMP DEVICES INSTALLED (POWER-ON DEFAULT 0000 0??1)
Bit
Name
R/W
Description
0
Local Temp = 1
R
This bit is permanently set to 1 since the local temperature sensor is
always available.
1
Remote 1 Temp = ?
R
This bit is set to 1 if the Remote 1 temperature sensor (TDM1) is installed.
(Automatically detected on power-up.)
2
Remote 2 Temp = ?
R
This bit is set to 1 if the Remote 2 temperature sensor (TDM2) is installed.
(Automatically detected on power-up.)
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
Table 28. REGISTER 30H, 31H, 32H – TEMP X* OFFSET REGISTERS (POWER-ON DEFAULT 00H)
Bit
<7:0>
Name
Offset
R/W
R/W
Description
This register contains an offset value that is automatically added to the
temperature value to reduce the effects of systemic offset errors.
* “x” denotes the number of the temperature channel. Register 30h is for Local temperature channel, 31h is for Remote 1 Temp (D1), 32h is for
Remote 2 Temp (D2).
Table 29. REGISTER 40H, 41H, 42H – TEMP X* FAULT ACTION (POWER-ON DEFAULT 08H)
Bit
Name
R/W
Description
0
Assert CFAULT on OT = 0
R/W
When this bit is set, CFAULT will be asserted when the Temp x*
temperature exceeds the Temp x* Temperature High Limit, not otherwise.
1
Alarm speed on OT = 0
R/W
When this bit is set, the fans(s) will go to alarm speed when the Temp x*
temperature exceeds the Temp x* Temperature High limit, not otherwise.
2
INT on OT = 0
R/W
When this bit is set, INT will be asserted when the Temp x* temperature
exceeds the Temp x* Temperature High Limit, not otherwise.
3
Alarm below low = 0
R/W
This bit indicates whether an alarm (INT, CFAULT, or Alarm Speed) is
asserted when temperature goes above or below the Low Limit.
1 = above, 0 = below. This bit is set to 1 at power-up if automatic fan
speed control is enabled by Pin 18, cleared otherwise.
4
Assert CFAULT on UT = 0
R/W
When this bit is set, CFAULT will be asserted when the Temp x*
temperature crosses the Temp x* Temperature Low Limit, not otherwise.
Bit 3 decides whether CFAULT is asserted for going above or below the
Low Limit. This bit is set to 1 if Automatic Fan Speed Control is enabled on
power-up.
5
Alarm speed on UT = 0
R/W
When this bit is set, the fans(s) will go to alarm speed when the Temp x*
temperature crosses the Temp x* Temperature Low Limit, not otherwise.
Bit 3 decides whether Alarm Speed is asserted for going above or below
the Low Limit.
6
INT on UT = 0
R/W
When this bit is set, INT will be asserted when the Temp x* temperature
crosses the Temp x* Temperature Low Limit, not otherwise. Bit 3 decides
whether INT is asserted for going above or below the Low Limit.
7
Latch Temp Fault = 0
R/W
This bit latches a temperature out-of-limit event (i.e., when the
temperature goes above the high limit or crosses the low limit) on the
Temp x* channel. This bit is cleared by writing a 0 to it.
* “x” denotes the number of the temperature channel. Register 40h is for the Local temperature channel, 41h is for Remote 1 Temp (D1), 42h
is for Remote 2 Temp (D2).
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ADM1029
Table 30. REGISTER 48H, 49H, 4AH – TEMP X* COOLING ACTION (POWER-ON DEFAULT 00H)
Bit
R/W
Description
0
Fan 1 = 0
Name
R/W
If a Temp x* out-of-limit event is generated such that fans should be
driven at Alarm Speed, Fan 1 will be set to this speed when this bit is set.
If no Temp x* out-of-limit event is present, Fan 1 will be set to the speed
determined by the automatic fan speed control circuit as a result of
temperature measurements on the Temp x* channel when this bit is set. If
this bit is not set, Temp x* temperature measurements will have no effect
on the speed of Fan 1.
1
Fan 2 = 0
R/W
If a Temp x* out-of-limit event is generated such that fans should be
driven at Alarm Speed, Fan 2 will be set to this speed when this bit is set.
If no Temp x* out-of-limit event is present, Fan 2 will be set to the speed
determined by the automatic fan speed control circuit as a result of
temperature measurements on the Temp x* channel when this bit is set. If
this bit is not set, Temp x temperature measurements have no effect on
the speed of Fan 2. While in theory it is possible, through setting of Bits 0
and 1 in registers 48h to 4Ah, to have any temperature channel controlling
any fan, in practice this is not feasible. A subset of possibilities only are
supported as follows:
Case 1: TDM1 controlling Fan 1
(Bit 0 in 49h set and/or
TDM2 controlling Fan 2
Bit 1 in 4Ah set, only)
Case 2: Local controlling Fan 1 and/or Fan 2 (Bits 0, 1 in 48h only set)
Case 3: TDM1 controlling Fan 1 and/or Fan 2 (Bits 0, 1 in 49h only set)
Case 4: TDM2 controlling Fan 1 and/or Fan 2 (Bits 0, 1 in 4Ah only set)
Case 5: Fan 1 and/or Fan 2 set to max speed (Bits 0, 1 in 48h, 49h,
(Default) determined by
temperature 4Ah all set)
measurements on all
three channels.
Other:
If Bits 0,1 in registers 48h, 49h, 4Ah are set inconsistent with
these cases, fans will run at the speeds determined by the
normal speed registers.
2
Reserved
R
Unused. Will read back 0.
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
* “x” denotes the number of the temperature channel. Register 48h is for the Local temperature channel. 49h is for Remote 1 Temp (D1), 4Ah
is for Remote 2 Temp (D2).
Table 31. REGISTER 80H, 81H, 82H – TEMP X* TMIN (POWER-ON DEFAULT 001??000)
Bit
<7:0>
Name
Temp x* TMIN
R/W
Description
R/W
This register contains the minimum temperature value for automatic fan
speed control based on the Temp x* temperature. On power-up Pin 18 is
sampled by the ADC to determine the default value for Temp x* TMIN. If
Pin 18 is strapped to GND or VCC, this register defaults to 32C, but
Automatic Fan Speed Control is disabled. There are eight strappable
options on Pin 18. These options are used to set Temp x* TMIN and the
Install bit in the Config Register (Reg 01h, Bit 0). The options are as
follows:
ADC MSBs R1
R2
Install
Temp x* TMIN
111
0

1
Disabled
101
18 kW
82 kW
1
48C
110
22 kW
47 kW
1
40C
100
12 kW
15 kW
1
32C
011
15 kW
12 kW
0
32C
010
47 kW
22 kW
0
40C
001
82 kW
18 kW
0
48C
000

0
0
Disabled
* “x” denotes the number of the temperature channel. Register 80h is for the Local temperature channel, 81h is for Remote 1 Temp (D1), 82h
is for Remote 2 Temp (D2).
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ADM1029
Table 32. REGISTER 88H, 89H, 8AH TEMP X* TRANGE/THYST (POWER-ON DEFAULT 51H)
Bit
Name
R/W
<3:0>
Temp x* TRANGE
R/W
Description
This nibble contains the temperature range over which automatic fan
speed control operates based on the Temp x* measured temperature.
Only a limited number of temperature ranges are supported as follows:
Bits <3:0>
0000
0001
0010
0011
0100
<7:4>
Temp x* THYST
R/W
TRANGE
5C
10C
20C
40C
80C
This nibble allows programmability of the Hysteresis level around the
temperature at which the fan being controlled by Temp x* will switch on in
automatic fan speed control mode. Values from 0C to 15C are possible.
If a value other than 0C is programmed as a Hysteresis value, the fan will
switch on when Temp x* goes above TMIN, but will remain on until
Temp x* falls below TMIN-THYST. Between TMIN-THYST and TMIN the fan
will run at the programmed minimum pulsewidth in the Fan x* Speed 1
register.
* “x” denotes the number of the temperature channel. Register 88h is for the Local temperature channel, 89h is for Remote 1 Temp (D1), 8Ah
is for Remote 2 Temp (D2).
Table 33. REGISTER 90H, 91H, 92H – TEMP X* HIGH LIMIT (POWER-ON DEFAULT 80C FOR LOCAL SENSOR,
100C FOR REMOTE SENSORS)
Bit
<7:0>
Name
Temp x* High Limit
R/W
R/W
Description
This register contains the high limit value for the Temp x* measurement.
* “x” denotes the number of the temperature channel. Register 90h is for the Local temperature channel. 91h is for Remote 1 Temp (D1), 92h
is for Remote 2 Temp (D2).
Table 34. REGISTER 98H, 99H, 9AH – TEMP X* LOW LIMIT (POWER-ON DEFAULT 60C FOR LOCAL SENSOR,
70C FOR REMOTE SENSORS)
Bit
<7:0>
Name
Temp x* Low Limit
R/W
R/W
Description
This register contains the low limit value for the Temp x* measurement.
* “x” denotes the number of the temperature channel. Register 98h is for the Local temperature channel. 99h is for Remote 1 Temp (D1), 9Ah
is for Remote 2 Temp (D2).
Table 35. REGISTER A0H, A1H, A2H – TEMP X* MEASURED VALUE (POWER−ON DEFAULT 00H)
Bit
<7:0>
Name
Temp x* Value
R/W
R
Description
This register contains the actual Temp x* measured value.
* “x” denotes the number of the temperature channel. Register A0h is for the Local temperature channel. A1h is for Remote 1 Temp (D1), A2h
is for Remote 2 Temp (D2).
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ADM1029
FAN REGISTERS
Table 36. REGISTER 02H – FAN SUPPORTED BY CONTROLLER (POWER-ON DEFAULT 03H)
Bit
Name
R/W
Description
0
Fan 1 = 1
R
This bit set to 1 means the ADM1029 can support Fan 1.
1
Fan 2 = 1
R
This bit set to 1 means the ADM1029 can support Fan 2.
2
Reserved
R
Unused. Will read back 0.
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
Table 37. REGISTER 03H – FANS SUPPORTED IN SYSTEM (POWER-ON DEFAULT 0000 00?1)
Bit
Name
R/W
Description
0
Fan 1 = 1
R/W
Indicates that Fan 1 is being used. Set to 1 on power-up, but can be
overwritten by software.
1
Fan 2 = ?
R/W
Indicates that Fan 2 is being used. Set by Pin 18 (TMIN/INSTALL) on
power-up, but can be overwritten by software.
2
Reserved
R
Unused. Will read back 0.
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
Table 38. REGISTER 07H – SET FAN X ALARM SPEED (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Fan 1 Alarm Speed = 0
R/W
When set to 1, Fan 1 will run at Alarm Speed.
1
Fan 2 Alarm Speed = 0
R/W
When set to 1, Fan 2 will run at Alarm Speed.
2
Reserved
R
Unused. Will read back 0.
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
Table 39. REGISTER 08H – SET FAN X HOT-PLUG SPEED (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Fan 1 Hot-Plug Speed = 0
R/W
When set to 1, Fan 1 will run at Hot-Plug Speed.
1
Fan 2 Hot-Plug Speed = 0
R/W
When set to 1, Fan 2 will run at Hot-Plug Speed.
2
0
R
Unused. Will read back 0.
3
0
R
Unused. Will read back 0.
4
0
R
Unused. Will read back 0.
5
0
R
Unused. Will read back 0.
6
0
R
Unused. Will read back 0.
7
0
R
Unused. Will read back 0.
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ADM1029
Table 40. REGISTER 09H – SET FAN X FULL SPEED (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Fan 1 Full Speed = 0
R/W
When set to 1 Fan 1 will run at Full Speed.
1
Fan 2 Full Speed = 0
R/W
When set to 1 Fan 2 will run at Full Speed.
2
Reserved
R
Unused. Will read back 0.
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
Table 41. REGISTER 0CH – FAN SPIN-UP REGISTER (POWER-ON DEFAULT 03H)
Bit
<7:4>
3
<2:0>
Name
Reserved
R/W
R
Description
Unused
Spin-up Disable
R/W
When this bit is set to 1, fan spin-up to full speed will be disabled.
Fan Spin-up Time
R/W
These bits select the spin-up time for the fans
000 = 16 seconds
001 = 8 seconds
010 = 4 seconds
011 = 2 seconds (Default)
100 = 1 second
101 = 1/4 second
110 = 1/16 second
111 = 1/64 second
Table 42. REGISTER 10H, 11H – FAN X* STATUS (POWER-ON DEFAULT 0000 0?0?)
Bit
<7:4>
Name
R/W
Description
Reserved
R
Unused
0
Missing = x
R
Reflects the state of Pins 4/21. Low means Fan x* is installed, High
means it is missing. This bit will automatically return Low if a missing fan
is replaced.
1
Missing _L = 0
R/W
This bit is edge-triggered and latches a Fan x* missing event on removal
of Fan x*. This bit is cleared by writing a 0 to it.
2
Fault_ = x
R
Inverse of Pin 2/23. Low on pin means Fan x* has a fault (Pins 2/23 Low),
High on pin means it is OK. This bit will automatically return Low if
Pin 2/23 goes high.
3
Fault_L_ = 0
R/W
This bit is edge-triggered and latches a Fan x* fault event on Pin 2/23.
This bit is cleared by writing a 0 to it. If the PRESENT pin for a fan input is
high (fan not installed) this bit will be cleared automatically.
4
Sleep = 0
R/W
When this bit is set, Fan x* will be stopped and no Fan x* faults will be
monitored. If Bit 4 in Fan x* Fault Action Register is set then Fan x* will
go to Alarm Speed if an overtemperature event is detected as per settings
in the Temp Fault Action Registers.
5
Hot Plug Priority
R/W
This bit indicates whether Fan x* runs at Hot-Plug Speed (bit set to 1) or
Alarm Speed (bit set to 0) if both modes are triggered.
6
Tach_Fault_L
R/W
Latches a Fan x* Tach fault. This bit is cleared by writing a 0 to it. If the
PRESENT pin for a fan input is high (fan not installed) this bit will be
cleared automatically.
7
Hot_Plug_L
R/W
This bit is edge-triggered and latches a Fan x* Hot-Plug event which is
the insertion of Fan x*. (Note difference to Bit 1) This bit is cleared by
writing a 0 to it. If a fan is Hot-Plug installed, it will run at Normal Speed.
* “x” denotes the fan number. Register 10h is for Fan 1 and Register 11h is for Fan 2.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
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ADM1029
Table 43. REGISTER 18H, 19H – FAN X* FAULT ACTION (POWER-ON DEFAULT BFH)
Bit
Name
R/W
Description
0
Assert CFAULT on Fault = 1
R/W
If this bit is set, CFAULT will be asserted when there is a fault (Tach or
Pins 2/23) on Fan x*.
1
Assert INT on Fault = 1
R/W
If this bit is set, INT will be asserted when there is a fault (Tach or
Pins 2/23) on Fan x*.
2
Assert CFAULT on Hot Unplug = 1
R/W
If this bit is set, CFAULT will be asserted when there is a hot unplug event
on Fan x*.
3
Assert INT on Hot Unplug = 1
R/W
If this bit is set, INT will be asserted when there is a hot unplug event on
Fan x*.
4
Thermal Override in Sleep = 1
R/W
If Bit 4 in Fan x* Status Register is set then Fan x* will go to Alarm
Speed if an overtemperature event is detected as per settings in Temp x*
Fault Action Registers, while this bit is set.
5
Drive Fault_ on Fault_L = 1
R/W
If Bit 3 or Bit 6 of Reg 10 is set, drive Pins 2, 23 low if a fault is generated.
6
Hot−Plug Speed on CFAULT in = 0
R/W
When this bit is set, Fan x* will go to Hot-Plug Speed when CFAULT is
pulled low externally.
7
Alarm on CFAULT = 1
R/W
When this bit is set, Fan x* will go to Alarm Speed when CFAULT is
pulled low externally.
* “x” denotes the fan number. Register 18h is for Fan 1 and Register 19h is for Fan 2.
Table 44. REGISTER 20H, 21H – FAN X* EVENT MASK (POWER-ON DEFAULT FFH)
Bit
Name
R/W
Description
0
Fan 1 = 1
R/W
If a fault (Tach or Pins 2/23) is detected on Fan x*, Fan 1 will be driven to
Alarm Speed when this bit is set.
1
Fan 2 = 1
R/W
If a fault (Tach or Pins 2/23) is detected on Fan x*, Fan 2 will be driven to
Alarm Speed when this bit is set.
2
Reserved
R
Unused. Will read back 1.
3
Reserved
R
Unused. Will read back 1.
4
Reserved
R
Unused. Will read back 1.
5
Reserved
R
Unused. Will read back 1.
6
Reserved
R
Unused. Will read back 1.
7
Reserved
R
Unused. Will read back 1.
* “x” denotes the fan number. Register 20h is for Fan 1 and Register 21h is for Fan 2.
Table 45. REGISTER 60H, 61H – FAN X* MINIMUM/ALARM SPEED (POWER-ON DEFAULT FFH)
Bit
Name
R/W
Description
3–0
Fan x Minimum Speed
R/W
This nibble contains the Normal speed value for Fan x*. When in
automatic fan this nibble will contain the minimum speed at which Fan x*
will run. The power-up default for the Min Speed should be 5hex which
corresponds to 33% PWM duty cycle.
7–4
Fan x Alarm Speed
R/W
This nibble contains the Alarm speed value for Fan x*.
* “x” denotes the fan number. Register 60h is for Fan 1 and 61h is for Fan 2.
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ADM1029
Table 46. REGISTER 68H, 69H – FAN X* CONFIGURATION (POWER-ON DEFAULT 2FH)
Bit
Name
R/W
Description
<3:0>
Fan x* Hot-Plug Speed
R/W
This nibble contains the Hot-plug speed value for Fan x*. This is the
speed the other fan(s) runs at if Fan x* is Hot-plug removed. If a fan is
Hot-plug installed, it will run at Normal Speed.
<5:4>
PWM Frequency
R/W
These bits allow programmability of the Nominal PWM Frequency for
Fan x*. The following options are supported:
Bits 5–4 PWM Freq
00
15.625 Hz
01
62.5 Hz
10
250 Hz (Default)
11
1000 Hz
<7:6>
Oscillator Frequency
R/W
These bits contain the oscillator frequency for the Fan x* tach
measurement. If set to 00, tach measurement is disabled for Fan x*.
Bit 7
Bit 6
Oscillator Frequency (Hz)
0
0
Measurement Disabled
0
1
470
1
0
940
1
1
1880
* “x” denotes the fan number. Register 68h is for Fan 1 and 69h is for Fan 2.
Table 47. REGISTER 70H, 71H – FAN X* TACH VALUE (POWER-ON DEFAULT 00H)
Bit
<7:0>
Name
Fan x* Tach Value
R/W
R
Description
This register contains the value of the Fan x* tachometer measurement.
* “x” denotes the fan number. Register 70h is for Fan 1 and 71h is for Fan 2.
Table 48. REGISTER 78H, 79H – FAN X* TACH HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
<7:0>
Name
Fan x* Tach High Limit
R/W
Description
R/W
This register contains the limit value for the Fan x* tachometer
measurement. Since the tachometer circuit counts between tach pulses, a
slow fan will result in a larger measured value, so exceeding the limit is
the way to detect a slow or stopped fan.
* “x” denotes the fan number. Register 78h is for Fan 1 and 79h is for Fan 2.
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ADM1029
GPIO REGISTERS
Table 49. REGISTER 04H – GPIOS SUPPORTED BY CONTROLLER (POWER-ON DEFAULT 7FH)
Bit
Name
R/W
Description
0
GPIO 0 = 1 (Pin 19)
R
This bit set to 1 means the ADM1029 can support GPIO0, available on Pin 19.
1
GPIO 1 = 1 (Pin 20)
R
This bit set to 1 means the ADM1029 can support GPIO1, available on Pin 20.
2
GPIO 2 = 1 (Pin 11)
R
This bit set to 1 means the ADM1029 can support GPIO2, available on Pin 11.
3
GPIO 3 = 1 (Pin 13)
R
This bit set to 1 means the ADM1029 can support GPIO3, available on Pin 13.
4
GPIO 4 = 1 (Pin 14)
R
This bit set to 1 means the ADM1029 can support GPIO4, available on Pin 14.
5
GPIO 5 = 1 (Pin 16)
R
This bit set to 1 means the ADM1029 can support GPIO5, available on Pin 16.
6
GPIO 6 = 1 (Pin 17)
R
This bit set to 1 means the ADM1029 can support GPIO6, available on Pin 17.
7
Reserved
R
Unused. Will read back 0.
Table 50. REGISTER 05H – GPIO PRESENT/AIN (POWER-ON DEFAULT 0????111)
Bit
Name
R/W
Description
0
GPIO 0 = 1
R/W
Indicates that GPIO0 is being used. Set to 1 on power-up, but can be
overwritten by software. Setting this bit to 0 means AIN0 is being used.
1
GPIO 1 = 1
R/W
Indicates that GPIO1 is being used. Set to 1 on power-up, but can be
overwritten by software. Setting this bit to 0 means AIN1 is being used.
2
GPIO 2 = 1
R/W
Indicates that GPIO2 is being used. Set to 1 on power-up, but can be
overwritten by software.
3
GPIO 3 = ?
R/W
Indicates that GPIO3 is being used. Setting this bit to 0 means TDM1 is being
used. The ADM1029 can detect on power-up if TDM1 is connected. If so then
this bit is set to 0, otherwise it is set to 1. The default setting can be overwritten
by software.
4
GPIO 4 = ?
R/W
Indicates that GPIO4 is being used. Setting this bit to 0 means TDM1 is being
used. The ADM1029 can detect on power-up if TDM1 is connected. If so then
this bit is set to 0, otherwise it is set to 1. The default setting can be overwritten
by software.
5
GPIO 5 = ?
R/W
Indicates that GPIO5 is being used. Setting this bit to 0 means TDM2 is being
used. The ADM1029 can detect on power-up if TDM2 is connected. If so then
this bit is set to 0, otherwise it is set to 1. The default setting can be overwritten
by software.
6
GPIO 6 = ?
R/W
Indicates that GPIO6 is being used. Setting this bit to 0 means TDM2 is being
used. The ADM1029 can detect on power-up if TDM2 is connected. If so then it
is set to 1. The default setting can be overwritten by software.
7
Reserved
R
Unused. Will read back 0.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
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ADM1029
Table 51. REGISTER 28H, 29H, 2AH, 2BH, 2CH, 2DH, 2EH – GPIOX* BEHAVIOR (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Direction = 0
R/W
This bit indicates the direction for GPIOx* pin. When set to 1 GPIOx* will
function as an input, when 0 GPIOx* will function as an output.
1
Polarity = 0
R/W
This bit indicates the polarity of the GPIOx* pin. When set to 1 GPIOx* will be
active high, when 0 GPIOx* will be active low.
2
Bit 2 = 0
R/W
If GPIOx* is configured as an input, CFAULT will be asserted if GPIOx* pin is
asserted while this bit is set. If GPIO2 is configured as an output, GPIO2 will be
asserted if a temperature High limit is exceeded while this bit is set. If automatic
fan speed control is enabled, this bit will be set by default. This can be used as
a SHUTDOWN signal for a catastrophic overtemperature event.
3
Bit 3 = 0
R/W
If GPIOx* is configured as an input, INT will be asserted if GPIOx* pin is
asserted while this bit is set. If GPIOx* is configured as an output, GPIOx* will
be asserted if a temperature Low limit is exceeded while this bit is set.
4
Bit 4 = 0
R/W
If GPIOx* is configured as an input, Fans will go to Alarm Speed if GPIOx* pin
is asserted while this bit is set. If GPIOx* is configured as an output, GPIOx*
will be asserted if a Fan Tach limit is exceeded while this bit is set.
5
Bit 5 = 0
R/W
If GPIOx* is configured as an input, Fans will go to Hot-plug Speed if GPIOx*
pin is asserted while this bit is set. If GPIOx* is configured as an output,
GPIOx* will be asserted if a Fan Fault (Pins 2/23) is detected while this bit is
set.
6
Bit 6 = 0
R
R/W
If GPIOx* is configured as an input, this bit will reflect state of GPIOx* pin.
If GPIOx* is configured as an output, GPIOx will be asserted if an AIN high
limit is exceeded while this bit is set.
7
Bit 7 = 0
R/W
If GPIOx* is configured as an input, this bit will latch a GPIOx* assertion
event. This bit is cleared by writing a 0 to it. If GPIOx* is configured as an
output, GPIOx* will be asserted if an AIN Low limit is exceeded while this bit is
set.
* “x”denotes the number of the GPIO pin. Register 28h controls GPIO0, 29h controls GPIO1, etc.
Table 52. REGISTER 38H, 39H, 3AH, 3BH, 3CH, 3DH, 3EH – GPIOX* EVENT MASK (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Fan 1 = 0
R/W
If GPIOx* is asserted such that fans should be driven at Alarm or Hot-plug
Speed, Fan 1 will be set to this speed when this bit is set.
1
Fan 2 = 0
R/W
If GPIOx* is asserted such that fans should be driven at Alarm or Hot-plug
Speed, Fan 2 will be set to this speed when this bit is set.
2
Reserved
R
Unused. Will read back 0.
3
Reserved
R
Unused. Will read back 0.
4
Reserved
R
Unused. Will read back 0.
5
Reserved
R
Unused. Will read back 0.
6
Reserved
R
Unused. Will read back 0.
7
Reserved
R
Unused. Will read back 0.
* “x” denotes the number of the GPIO pin. Register 38h is for GPIO0, 39h is for GPIO1 etc.
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ADM1029
AIN REGISTERS
Table 53. REGISTER 05H – GPIO PRESENT/AIN (POWER-ON DEFAULT 0????111)
Bit
Name
R/W
Description
0
GPIO 0 = 1
R/W
Indicates that GPIO0 is being used. Set to 1 on power-up, but can be
overwritten by software. Setting this bit to 0 means AIN0 is being used.
1
GPIO 1 = 1
R/W
Indicates that GPIO1 is being used. Set to 1 on power-up, but can be
overwritten by software. Setting this bit to 0 means AIN1 is being used.
2
GPIO 2 = 1
R/W
Indicates that GPIO2 is being used. Set to 1 on power-up, but can be
overwritten by software.
3
GPIO 3 = ?
R/W
Indicates that GPIO3 is being used. Setting this bit to 0 means TDM1
is being used. The ADM1029 can detect on power-up if TDM1 is
connected. If so, this bit is set to 0; otherwise it is set to 1. The default
setting can be overwritten by software.
4
GPIO 4 = ?
R/W
Indicates that GPIO4 is being used. Setting this bit to 0 means TDM1
is being used. The ADM1029 can detect on power-up if TDM1 is
connected. If so, this bit is set to 0; otherwise it is set to 1. The default
setting can be overwritten by software.
5
GPIO 5 = ?
R/W
Indicates that GPIO5 is being used. Setting this bit to 0 means TDM2
is being used. The ADM1029 can detect on power-up if TDM2 is
connected. If so, this bit is set to 0; otherwise it is set to 1. The default
setting can be overwritten by software.
6
GPIO 6 = ?
R/W
Indicates that GPIO6 is being used. Setting this bit to 0 means TDM2
is being used. The ADM1029 can detect on power-up if TDM2 is
connected. If so, this bit is set to 0; otherwise it is set to 1. The default
setting can be overwritten by software.
7
Reserved
R
Unused. Will read back 0.
NOTE: Question marks on this and following pages indicate bit settings that depend on the state of certain pins on power-up.
Table 54. REGISTER 50H, 51H – AINX* BEHAVIOR (POWER-ON DEFAULT 00H)
Bit
0
1
Name
Assert CFAULT on HI_LIM = 0
Alarm speed on HI_LIM = 0
R/W
Description
R/W
When this bit is set, CFAULT is asserted when AINx* exceeds the
AINx* high limit.
R/W
When this bit is set, the fans go to alarm speed when AINx* exceeds
the AINx* high limit.
When this bit is set, INT is asserted when AINx* exceeds the AINx*
high limit.
2
INT on HI_LIM = 0
R/W
3
Alarm below low = 0
R/W
This bit indicates whether an alarm (INT, CFAULT or Alarm Speed) is
asserted when AINx* goes above or below the Low Limit. 1 = above.
0 = below.
4
Assert CFAULT on LO_LIM = 0
R/W
When this bit is set, CFAULT is asserted when AINx* crosses the
AINx* low limit. Bit 3 decides whether CFAULT is asserted for going
above or below the Low Limit.
5
Alarm speed on LO_LIM = 0
R/W
When this bit is set, the fans go to alarm speed when AINx* crosses
the AINx* low limit. Bit 3 decides whether Alarm Speed is asserted for
going above or below the Low Limit.
6
INT on LO_LIM = 0
R/W
When this bit is set, INT is asserted when AINx* crosses the AINx*
low limit. Bit 3 decides whether INT is asserted for going above or below the Low Limit.
7
Latch AIN Fault = 0
R/W
This bit latches an out-of-limit event (i.e., when AINx* goes above the
high limit or crosses the low limit) on the AINx* channel. This bit is
cleared by writing a 0 to it.
* “x” denotes the number of the AIN channel. Register 50h controls AIN0 and 51h controls AIN1.
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ADM1029
Table 55. REGISTER 58H, 59H – AINX* EVENT MASK (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
0
Fan 1 = 0
R/W
If an AINx* out-of-limit event is generated such that fans should be driven at
Alarm Speed, Fan 1 will be set to this speed when this bit is set.
1
Fan 2 = 0
R/W
If an AINx* out-of-limit event is generated such that fans should be driven at
Alarm Speed, Fan 2 will be set to this speed when this bit is set.
2
Reserved
R/W
Undefined
3
Reserved
R/W
Undefined
4
Reserved
R/W
Undefined
5
Reserved
R/W
Undefined
6
Reserved
R/W
Undefined
7
Reserved
R/W
Undefined
* “x” denotes the number of the AIN channel. Register 58h is for AIN0 and 59h is for AIN1.
Table 56. REGISTER A8H, A9H – AINX* HIGH LIMIT (POWER-ON DEFAULT FFH)
Bit
<7:0>
Name
AINx* High Limit
R/W
R/W
Description
This register contains the high limit value for the AINx* analog input channel.
* “x” denotes the number of the AIN channel. Register A8h is for AIN0 and A9h is for AIN1.
Table 57. REGISTER B0H, B1H – AINX* LOW LIMIT (POWER-ON DEFAULT 00H)
Bit
<7:0>
Name
AINx* High Limit
R/W
R/W
Description
This register contains the high limit value for the AINx* analog input channel.
* “x” denotes the number of the AIN channel. Register B0h is for AIN0 and B1h is for AIN1.
Table 58. REGISTER B8H, B9H – AINX* MEASURED VALUE (POWER-ON DEFAULT 00H)
Bit
<7:0>
Name
AINx* Value
R/W
R
Description
This register contains the measured value of the AINx* analog input channel.
* “x” denotes the number of the AIN channel. Register B8h is for AIN0 and B9h is for AIN1.
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ADM1029
MISCELLANEOUS REGISTERS
Table 59. REGISTER 0BH – S/W RESET (POWER-ON DEFAULT 00H)
Bit
<7:0>
Name
R/W
S/W Reset
R/W
Description
Writing A6 hex to this register location causes a software reset identical to a
power-on reset. This register is self-clearing so reading from it after the
software reset has completed will result in 00 hex being read.
Table 60. REGISTER 0DH – MANUFACTURER’S ID (POWER-ON DEFAULT 41H)
Bit
Name
R/W
<7:0>
Manufacturer’s ID Code
R
Description
This register contains the manufacturer’s ID code for the device.
Table 61. REGISTER 0EH – REVISION (POWER-ON DEFAULT 00H)
Bit
Name
R/W
Description
<3:0>
Minor Revision Code
R
This nibble contains the manufacturer’s code for minor revisions to the device.
<7:4>
Minor Revision Code
R
This nibble contains the manufacturer’s code for major revisions to the device
which would likely require a S/W revision.
Table 62. REGISTER 0FH – MANUFACTURER’S TEST REGISTER (POWER-ON DEFAULT 00H)
Bit
<7:0>
Name
R/W
Manufacturer’s Test
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 63. ORDERING INFORMATION TABLE
Model*
Temperature Range
Package Type
Package Option
Shipping†
ADM1029ARQZ−R7
0C to 100C
24-lead QSOP
RQ−24
1,000 Tape & Reel
* Z = Pb-free part.
†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.
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ADM1029
PACKAGE DIMENSIONS
QSOP24 NB
CASE 492B−01
ISSUE A
2X
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME
Y14.5M, 1994.
2. CONTROLLING DIMENSION: MILLIMETERS.
3. DIMENSION b DOES NOT INCLUDE DAMBAR
PROTRUSION.
4. DIMENSION D DOES NOT INCLUDE MOLD FLASH,
PROTRUSIONS, OR GATE BURRS. MOLD FLASH,
PROTRUSIONS, OR GATE BURRS SHALL NOT
EXCEED 0.15 PER SIDE. DIMENSION E1 DOES NOT
INCLUDE INTERLEAD FLASH OR PROTRUSION.
INTERLEAD FLASH OR PROTRUSION SHALL NOT
EXCEED 0.15 PER SIDE. D AND E1 ARE
DETERMINED AT DATUM H.
5. DATUMS A AND B ARE DETERMINED AT DATUM H.
0.20 C D
D
24
A
D
C
13
GAUGE
PLANE
L2
E
E1
C
L
DETAIL A
2X
2X 12 TIPS
0.20 C D
1
e
12
24X
B
b
0.25
0.10 C
M
C A-B D
h x 45 _
A
0.10 C
24X
0.25 C D
A1
C
H
SEATING
PLANE
DETAIL A
M
DIM
A
A1
b
C
D
E
E1
e
h
L
L2
M
MILLIMETERS
MIN
MAX
1.35
1.75
0.10
0.25
0.20
0.30
0.19
0.25
8.65 BSC
6.00 BSC
3.90 BSC
0.635 BSC
0.22
0.50
0.40
1.27
0.25 BSC
0_
8_
SOLDERING FOOTPRINT
24X
24X
0.42
1.12
24
13
6.40
1
12
0.635
PITCH
DIMENSIONS: MILLIMETERS
Protected by U.S. Patent Numbers 6,255,973 and 6,188,189
Pentium is a registered trademark of Intel Corporation.
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
Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.
PUBLICATION ORDERING INFORMATION
LITERATURE FULFILLMENT:
Literature Distribution Center for ON Semiconductor
P.O. Box 5163, Denver, Colorado 80217 USA
Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada
Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada
Email: [email protected]
N. American Technical Support: 800−282−9855 Toll Free
USA/Canada
Europe, Middle East and Africa Technical Support:
Phone: 421 33 790 2910
Japan Customer Focus Center
Phone: 81−3−5817−1050
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50
ON Semiconductor Website: www.onsemi.com
Order Literature: http://www.onsemi.com/orderlit
For additional information, please contact your local
Sales Representative
ADM1029/D
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