MAXIM MAX6664AEE

19-2865; Rev 1; 12/03
Temperature Monitors and
PWM Fan Controllers
Internal watchdog set points are provided for both local
and remote temperatures. There are two comparison
set points for local temperatures and two for remote
temperatures. When a set point is crossed, the
MAX6653/MAX6663/MAX6664 assert either the INT or
THERM outputs. These outputs can be used as interrupts, clock throttle signals, or overtemperature shutdown signals. Two pins on the MAX6653 control the
power-up values of the comparison set points, providing fail-safe protection even when the system is unable
to program the trip temperatures. The MAX6653 has
two additional shutdown outputs, SDR and SDL, that
are triggered when the remote or local temperatures
exceed the programmed shutdown set points. The INT
output for the MAX6653/MAX6663 and THERM outputs
for the MAX6653/MAX6663/MAX6664 can also function
as inputs if either is pulled low to force the fan to full
speed, unless this function is masked by the user.
The MAX6653/MAX6663/MAX6664 are available in
16-pin QSOP packages and operate over the -40°C to
+125°C temperature range.
Features
♦ Remote-Junction Temperature Sensor Within
±1°C Accuracy (+60°C to +100°C)
♦ ACPI-Compatible Programmable Temperature
Alarms
♦ 0.125°C Resolution Local and Remote-Junction
Temperature Measurement
♦ Programmable Temperature Offset for System
Calibration
♦ SMBus 2-Wire Serial Interface with Timeout
♦ Automatic or Manual Fan-Speed Control
♦ PWM Fan Control Output
♦ Fan-Speed Monitoring and Watchdog
♦ Fan Fault and Failure Indicators
♦ Compatible with 2-Wire or 3-Wire Fans
(Tachometer Output)
♦ +3V to +5.5V Supply Range
♦ Additional Shutdown Set Point (MAX6653)
♦ Controlled PWM Rise/Fall Times
Ordering Information
PART
TEMP RANGE
MAX6653AEE
-40°C to +125°C
16 QSOP
MAX6663AEE
-40°C to +125°C
16 QSOP
MAX6664AEE
-40°C to +125°C
16 QSOP
Applications
Personal Computers
Servers
Workstations
Telecom Equipment
Networking Equipment
Test Equipment
Industrial Controls
Pin Configurations
TOP VIEW
PWM_OUT 1
16 SMBCLK
TACH/AIN 2
15 SMBDATA
CRT0 3
CRT1 4
14 INT
MAX6653
13 ADD
GND 5
12 SDR
VCC 6
11 SDL
THERM 7
10 DXP
FAN_FAULT 8
Typical Operating Circuits appear at end of data sheet.
Functional Diagram appears at end of data sheet.
PIN-PACKAGE
9
DXN
QSOP
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX6653/MAX6663/MAX6664
General Description
The MAX6653/MAX6663/MAX6664 are ACPI-compliant
local and remote-junction temperature sensors and fan
controllers. These devices measure their own die temperature, as well as the temperature of a remote-PN
junction and control the speed of a DC cooling fan
based on the measured temperature. Remote temperature measurement accuracy is ±1°C from +60°C to
+100°C. Temperature measurement resolution is
0.125°C for both local and remote temperatures.
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
ABSOLUTE MAXIMUM RATINGS
All Voltages Are Referenced to GND
TACH/AIN ..............................................................-0.3V to +5.5V
VCC ...........................................................................-0.3V to +6V
DXP, ADD, CRIT0, CRIT1........................-0.3V to + (VCC + 0.3V)
DXN .......................................................................-0.3V to +0.8V
SMBDATA, SMBCLK, INT, THERM,
FAN_FAULT, SDL, SDR............................................-0.3V to +6V
SMBDATA, INT, THERM, FAN_FAULT,
PWM_OUT Current..............................................-1mA to +50mA
DXN Current .......................................................................±1mA
ESD Protection (all pins, Human Body Model) ..................2000V
Continuous Power Dissipation (TA = +70°C)
16-Pin QSOP (derate 8.3 mW/°C above +70°C)..........667mW
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +165°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC = +3.0V to +5.5V, TA = 0°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25°C.) (Note1)
PARAMETER
Operating Supply Voltage Range
SYMBOL
Standby Current
Operating Current
Average Operating Current
External Temperature Error
Internal Temperature Error
CONDITIONS
VCC
SMBDAT = SMBCLK = 1, register 00h = 00h
IS
TACHOMETER Conversion Cycle
Time
2
UNITS
5.5
V
10
µA
0.5
1
mA
Conversion rate = 4Hz (default)
150
300
µA
VCC = +3.3V, TA = 0°C to +100°C,
+60°C ≤ TR ≤ +100°C
±1
VCC = +3.3V, 0°C ≤ TR ≤ +100°C
±3
VCC = +3.3V, -25°C ≤ TR ≤ +125°C
±4
VCC = +3.3V, 0°C ≤ TA ≤ +100°C
±2
VCC = +3.3V, -40°C ≤ TA ≤ +125°C
±4
0.125
°C
°C
°C
11
Bits
(Note 2)
6
%
255
Divisor = 1, fan count = 153
4400
Divisor = 2, fan count = 153
2200
Divisor = 4, fan count = 153
1100
Divisor = 8, fan count = 153
Internal Clock Frequency
MAX
SMBDAT = SMBCLK = 1
Fan TACHOMETER Full-Scale
Count
TACHOMETER Nominal Input
RPM
TYP
3.0
Temperature Resolution
(Internal and External)
Fan TACHOMETER Accuracy
MIN
RPM
550
254
270
637
_______________________________________________________________________________________
286
kHz
ms
Temperature Monitors and
PWM Fan Controllers
MAX6653/MAX6663/MAX6664
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.0V to +5.5V, TA = 0°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25°C.) (Note1)
PARAMETER
SYMBOL
CONDITIONS
MIN
Temperature Conversion Time
TYP
MAX
250
Conversion Rate Timing Error
Remote-Diode Sourcing Current
UNITS
ms
(Note 2)
25
25
High level
80
100
120
Low level
8
10
12
%
µA
DXN Source Voltage
0.7
V
TACHOMETER Input Hysteresis
100
mV
Output Low Voltage (Sink Current)
VOL
SDL, SDR, THERM, FAN_FAULT, SMBDATA,
PWM_OUT, VCC = +3V, IOUT = 6mA,
INT, VCC = +3V, IOUT = 4mA
Output High Leakage Current
IOH
INT, SDL, SDR, THERM, FAN_FAULT,
SMBDATA, PWM_OUT
Logic Low Input Voltage
VIL
SMBDATA, SMBCLK, INT, THERM, TACH/AIN
VIH
SMBDATA, SMBCLK, INT,
THERM, TACH/AIN
Logic High Input Voltage
Input Leakage Current
Input Capacitance
ILEAK
3.0V
2.2
5.5V
2.6
0.4
V
1
µA
0.8
V
V
SMBDATA, SMBCLK, INT, THERM;
VIN = VCC or GND
±1
CIN
5
µA
pF
SMBus TIMING
Serial Clock Frequency
fSCLK
(Note 2)
10
100
kHz
Clock Low Period
tLOW
10% to 10% (Note 2)
4
µs
Clock High Period
tHIGH
90% to 90% (Note 2)
4.7
µs
Bus Free Time Between Stop and
Start Condition
tBUF
(Note 2)
4.7
µs
SMBus Start Condition Setup
Time
tSU:STA
90% of SMBCLK to 90% of SMBDATA (Note 2)
4.7
µs
Start Condition Hold Time
tHD:STO
10% of SMBDATA to 10% of SMBCLK (Note 2)
4
µs
Stop Condition Setup Time
tSU:STO
90% of SMBCLK to 10% of SMBDATA (Note 2)
4
µs
Data Setup Time
tSU:DAT
10% of SMBDATA to 10% of SMBCLK (Note 2)
250
ns
Data Hold Time
tHD:DAT
10% of SMBCLK to 10% of SMBDATA (Note 2)
300
SMBus Fall Time
tF
(Note 2)
300
ns
SMBus Rise Time
tR
(Note 2)
1000
ns
45
ms
SMBus Timeout
29
ns
37
+85oC.
Note 1: Tested at
Values through the temperature range are guaranteed by design.
Note 2: Not production tested, guaranteed by design.
_______________________________________________________________________________________
3
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
4.0
3.5
3.0
1.5
TEMPERATURE ERROR (°C)
400
350
300
250
200
150
100
2.5
0
3.5
4.0
4.5
5.0
-0.5
-1.0
1
2
3
4
-40 -25 -10 5 20 35 50 65 80 95 110 125
CONVERSION RATE (Hz)
REMOTE-DIODE TEMPERATURE (°C)
LOCAL TEMPERATURE ERROR
vs. DIE TEMPERATURE
REMOTE TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
LOCAL TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
1.0
0.5
0
-0.5
-1.0
250mVP-P
8
7
6
5
4
3
100mVP-P
2
-1.5
1
-2.0
0
0.01
0.1
1
10
6
20mVP-P
2
0
100mVP-P
5
20mVP-P
3
2
COMMON-MODE NOISE FREQUENCY (MHz)
100
10
100
1
0
-1
-2
-3
-4
0
10
1
MAX6653 toc09
30mVP-P
4
0.1
TEMPERATURE ERROR
vs. DXP-DXN CAPACITANCE
MAX6653 toc08
7
6
0.01
POWER-SUPPLY NOISE FREQUENCY (MHz)
1
1
1
0
0.001
TEMPERATURE ERROR (°C)
8
0.1
2
100
8
TEMPERATURE ERROR (°C)
40mVP-P
0.01
3
TEMPERATURE ERROR
vs. DIFFERENTIAL-MODE NOISE FREQUENCY
MAX6653 toc07
12
-2
0.0001 0.001
4
POWER-SUPPLY NOISE FREQUENCY (MHz)
TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCY
4
250mVP-P
5
-2
DIE TEMPERATURE (°C)
10
6
-1
0.001
-40 -25 -10 5 20 35 50 65 80 95 110 125
7
MAX6653 toc06
9
REMOTE TEMPERATURE ERROR (°C)
1.5
10
MAX6653 toc05
MAX6653 toc04
LOCAL TEMPERATURE ERROR (°C)
0
SUPPLY VOLTAGE (V)
2.0
4
0.5
-2.0
0
5.5
REMOTE TEMPERATURE ERROR (°C)
3.0
1.0
-1.5
50
2.0
MAX6653 toc03
450
SUPPLY CURRENT (µA)
4.5
2.0
MAX6653 toc02
500
MAX6653 toc01
5.0
STANDBY SUPPLY CURRENT (µA)
REMOTE TEMPERATURE ERROR
vs. REMOTE-DIODE TEMPERATURE
AVERAGE OPERATING SUPPLY CURRENT
vs. CONVERSION RATE
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
TEMPERATURE ERROR (°C)
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
-5
0.01
0.1
1
10
100
DIFFERENTIAL-MODE NOISE FREQUENCY (MHz)
1
10
DXP-DXN CAPACITANCE (nF)
_______________________________________________________________________________________
100
Temperature Monitors and
PWM Fan Controllers
PIN
MAX6653
QSOP
MAX6663/
MAX6664
QSOP
NAME
1
1
PWM_OUT
Digital Output (Open Drain). Pulse-width modulated output to external power transistor.
Requires a pullup resistor (10kΩ typ).
2
2
TACH/AIN
Digital/Analog Input. Fan tachometer input. May be reprogrammed as an analog input to
measure speed of a 2-wire fan. See Figure 5.
3
—
CRIT0
Input. Used in conjunction with CRIT1 to set THERM and SHUTDOWN default set points
(see Table 1).
4
—
CRIT1
Input. Used in conjunction with CRIT0 to set THERM and SHUTDOWN default set points
(see Table 1).
—
3, 4
N.C.
No Connection. Not internally connected.
5
5
GND
Ground
6
6
VCC
Power Supply. Bypass with a 0.01µF capacitor to GND.
FUNCTION
Digital I/O (Open Drain). An active-low thermal-overload output to indicate that the
overtemperature set point has been exceeded. Also acts as an input to provide external
fan control. When this pin is pulled low by an external signal, a status bit is set and the
fan speed is forced full-on. Requires a pullup resistor (10kΩ typ).
7
7
THERM
8
8
FAN_FAULT
9
9
DXN
Combined Current Sink and A/D Negative Input. DXN is internally biased to a diode
voltage above ground.
10
10
DXP
Combined Current Source and A/D Positive Input for the Remote-Diode Channel. Do not
leave DXP floating; connect DXP to DXN if no remote diode is used. Place a 2200pF
capacitor between DXP and DXN for noise filtering.
11
—
SDL
An Active-Low Open-Drain Output. It indicates that local temperature is above the
shutdown set point. Normally used to directly deactivate the CPU power supply.
12
—
SDR
An Active-Low Open-Drain Output. It indicates that remote temperature is above the
shutdown set point. Normally used to directly deactivate the CPU power supply.
—
11, 12
N.C.
Internal Connection. Leave floating or connect to GND.
13
13
ADD
Three-State Logic Input. Sets the 2 lower bits of the device SMBus address (Table 2).
ADD is not an ordinary logic input pin; ADD should be connected to VCC, GND, or float.
Digital Output (Open Drain). Can be programmed as an interrupt output for
temperature/fan speed interrupts. Requires a pullup resistor (10kΩ typ). For the
MAX6653/MAX6663, it can be used also as an input. If pulled low, fan speed is forced to
maximum unless masked.
14
14
INT
15
15
SMBDATA
16
16
SMBCLK
—
12
N.C.
Digital Output (Active Low, Open Drain). Signals a fan fault. Requires a pullup resistor
(10kΩ typ).
SMBus Serial-Data Input/Output (Open Drain). Requires a pullup resistor (10kΩ typ).
SMBus Serial-Clock Input. Requires a pullup resistor (10kΩ typ).
Internal Connection. Leave floating or connect to GND.
_______________________________________________________________________________________
5
MAX6653/MAX6663/MAX6664
Pin Description
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
Table 1. MAX6653 Power-Up Set-Point Decoding
CRIT1
CRIT0
GND
GND
THERM SET POINT (°C)
LOCAL
REMOTE
LOCAL
Open
85
55
110
80
GND
90
60
115
85
GND
VCC
95
65
120
90
Open
Open
100
70
125
95
Open
GND
105
75
125
95
Open
VCC
110
80
125
95
VCC
Open
115
85
125
95
VCC
GND
120
90
125
95
VCC
VCC
125
95
125
95
Detailed Description
The MAX6653/MAX6663/MAX6664 are local/remote
temperature monitors and fan controllers for microprocessor-based systems. These devices communicate with the system through a serial SMBus interface.
The serial bus controller features a hard-wired address
pin for device selection, an input line for a serial clock,
and a serial line for reading and writing addresses and
data (see Functional Diagram).
The MAX6653/MAX6663/MAX6664 fan control section
can operate in three modes. In the automatic fan-control
mode, the fan’s power-supply voltage is automatically
adjusted based on temperature. The control algorithm
parameters are programmable to allow optimization to
the characteristics of the fan and the system. RPM select
mode forces the fan speed to a programmed tachometer value. PWM duty cycle select mode allows user
selection of the PWM duty cycle. PWM rise and fall times
are limited to maximize fan reliability.
To ensure overall system reliability, the MAX6653/
MAX6663/MAX6664 feature an SMBus timeout so that
the MAX6653/MAX6663/MAX6664 can never “lock” the
SMBus. Furthermore, the availability of hard-wired
default values for critical temperature set points
ensures the MAX6653 controls critical temperature
events properly even if the SMBus is “locked” by some
other device on the bus.
SMBus Digital Interface
From a software perspective, the MAX6653/MAX6663/
MAX6664 appear as a set of byte-wide registers. These
devices use a standard SMBus 2-wire/I2C-compatible
serial interface to access the internal registers. The
MAX6653/MAX6663/MAX6664 slave address can be
set to three different values by the input pin ADD
6
SHUTDOWN SET POINT (°C)
REMOTE
(Table 2) and, therefore, a maximum of three MAX6653/
MAX6663/MAX6664 devices can share the same bus.
The MAX6653/MAX6663/MAX6664 employ four standard SMBus protocols: Write Byte, Read Byte, Send
Byte, and Receive Byte (Figures 1, 2, and 3). The shorter Receive Byte protocol allows quicker transfers, provided that the correct data register was previously
selected by a Read Byte instruction. Use caution with
the shorter protocols in multimaster systems, since a
second master could overwrite the command byte without informing the first master.
Alert Response Address
The MAX6653/MAX6663/MAX6664 respond to the
SMBus alert response address, an event which typically occurs after an SMBus host master detects an INT
interrupt signal going active (referred to as ALERT in
SMBus nomenclature). When the host master puts the
alert response address (0001 1001) on the bus, all
devices with an active INT output respond by putting
their own address onto the bus. The alert response can
activate several different slave devices simultaneously,
similar to the I2C general call. If more than one slave
attempts to respond, bus arbitration rules apply, and
the device with the lowest address code wins. The
master then services the devices from the lowest
address up.
Table 2. MAX6653/MAX6663/MAX6664
Slave Address Decoding
ADD PIN
ADDRESS
GND
0101 100
No connect
0101 110
VCC
0101 101
_______________________________________________________________________________________
Temperature Monitors and
PWM Fan Controllers
MAX6653/MAX6663/MAX6664
Write Byte Format
S
ADDRESS
WR
ACK
COMMAND
7 bits
ACK
DATA
8 bits
Slave Address: equivalent to chip-select line of
a 3-wire interface
ACK
P
8 bits
Command Byte: selects which
register you are writing to
Data Byte: data goes into the register
set by the co mma nd byte ( to se t
thresholds, configuration masks, and
sampling rate)
Read Byte Format
S
WR
ADDRESS
ACK
COMMAND
7 bits
ACK
S
Slave Address: equivalent to chip-select line
ADDRESS
RD
ACK
DATA
7 bits
Command Byte: selects
which register you are
reading from
P
Data Byte: reads from
the register set by the
command byte
Receive Byte Format
WR
ACK
COMMAND
7 bits
ACK
P
S
ADDRESS
8 bits
RD
ACK
DATA
7 bits
P
///
8 bits
Data Byte: reads data from
the register commanded
by the last read byte or
write byte transmission;
also used for SMBus alert
response return address
Data Byte: writes data to the
register commanded by the
last read byte or write byte
transmission
S = Start condition
P = Stop condition
///
8 bits
Slave Address: repeated
due to change in dataflow direction
Send Byte Format
S
ADDRESS
8 bits
Shaded = Slave transmission
/ / / = Not acknowledged
Figure 1. SMBus Protocols
A
tLOW
B
tHIGH
C
D
E
F
G
H
I
J
K
L
M
SMBCLK
SMBDATA
tSU:STA
tHD:STA
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
E = SLAVE PULLS SMBDATA LINE LOW
tSU:DAT
tHD:DAT
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE
H = LSB OF DATA CLOCKED INTO SLAVE
I = MASTER PULLS DATA LINE LOW
tSU:STO tBUF
J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION, DATA EXECUTED BY SLAVE
M = NEW START CONDITION
Figure 2. SMBus Write Timing Diagram
_______________________________________________________________________________________
7
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
A
tLOW
B
tHIGH
C
D
E
F
G
H
I
J
K
L
M
SMBCLK
SMBDATA
tSU:STA
tHD:STA
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
E = SLAVE PULLS SMBDATA LINE LOW
tSU:DAT
tHD:DAT
tSU:STO tBUF
J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLEAR PULSE
L = STOP CONDITION, EXECUTED BY SLAVE
M = NEW START CONDITION
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO MASTER
H = LSB OF DATA CLOCKED INTO MASTER
I = MASTER PULLS DATA LINE LOW
Figure 3. SMBus Read Timing Diagram
The MAX6663 resets its INT output and some of the
status bits in the status register after responding to an
alert response address; however, if the error condition
that caused the interrupt is still present, INT is reasserted on the next monitoring cycle. INT is maskable to
allow full control of ALERT conditions.
Temperature Measurement
The MAX6653/MAX6663/MAX6664 contain on-chip temperature sensors to sense their own die (local) temperatures. These devices can also measure remote
temperatures such as the die temperature of CPUs or
other ICs having on-chip temperature-sensing diodes, or
discrete diode-connected transistors as shown in the
Typical Operating Circuits. For best accuracy, the discrete diode-connected transistor should be a small-signal
device with its collector and base connected together.
The on-chip ADC converts the sensed temperature and
outputs the temperature data in the format shown in
Tables 3 and 4. The temperature measurement resolution
is 0.125°C for both local and remote temperatures. The
temperature accuracy is within ±1°C for remote temperature measurements from +60°C to +100°C.
The Local Temperature Offset (0Dh) and Remote
Temperature Offset (0Eh) registers allow the measured
temperature to be increased or decreased by a fixed
value to compensate for errors due to variations in diode
resistance and ideality factor (see the Remote Diode
Considerations section). The reported temperature is the
measured temperature plus the correction value. Both the
measured temperature and the reported value are limited
by the sensor’s temperature range. For example, if a
remote thermal diode is being measured and its temperature is 135°C, the measured temperature is the maximum
8
value of 127.875°C. If the remote offset value is set to 10°C, the reported value is 117.875°C, not 125°C.
The temperature conversion rate is programmable using
bits [4:2] of the fan filter register (23h) as shown in Table 5.
The DXN input is biased at 0.65V above ground by an
internal diode to set up the analog-to-digital inputs for a
differential measurement. The worst-case DXP-DXN differential input voltage range is from 0.25V to 0.95V.
Excess resistance in series with the remote diode causes about 0.5°C error per ohm. Likewise, a 200µV offset
voltage forced on DXP-DXN causes about 1°C error.
High-frequency EMI is best filtered at DXP and DXN with
an external 2200pF capacitor. This value can be
increased to about 3300pF, including cable capacitance.
Capacitance higher than 3300pF introduces errors due to
the rise time of the switched current source.
Table 3. Temperature Data High Byte Format
TEMP (°C)
DIGITAL
OUTPUT (°C)
DIGITAL OUTPUT
(BINARY)
130.00
+127
0111 1111
127.00
+127
0111 1111
126.00
+126
0111 1110
25.25
+25
0001 1001
0.50
0
0000 0000
0.00
0
0000 0000
-1
—
1111 1111
-125
—
1000 0011
-128
—
1000 0000
Diode fault
(short or open)
—
1000 0000
_______________________________________________________________________________________
Temperature Monitors and
PWM Fan Controllers
MAX6653/MAX6663/MAX6664
Table 4. Temperature Data Low Byte Format Structure: LLLXXRRR*
FRACTIONAL TEMPERATURE (°C)
DIGITAL OUTPUT (LOCAL)
DIGITAL OUTPUT (REMOTE)
0.000
000X XXXX
XXX XX 000
0.125
001X XXXX
XXX XX 001
0.25
010X XXXX
XXX XX 010
0.375
011X XXXX
XXX XX 011
XXX XX 100
0.5
100X XXXX
0.625
101X XXXX
XXX XX 101
0.75
110X XXXX
XXX XX 110
0.875
111X XXXX
XXX XX 111
*Where: LLL = local fractional temperature bits, XX = don’t care, RRR = remote fractional temperature bits.
Table 5. Temperature Conversion Rate Setting (Fan Filter Register (23h)—POR = 111)
BIT 4
BIT 3
BIT2
CONVERSION RATE (Hz)
CONVERSION TIME (s)
0
0
0
0.0625
16
0
0
1
0.125
8
4
0
1
0
0.25
0
1
1
0.5
2
1
0
0
1
1
1
0
1
2
0.5
1
1
0
4
0.25
1
1
1
4
0.25
Table 6. Threshold Limit Registers
NAME
ADDRESS
R/W
MAX6653 POR VALUE
MAX6663/MAX6664 POR STATE
DESCRIPTION
Local temp high limit
LTH
14h
R/W
Set by CRIT0 and CRIT1
0011 1100
LTL
15h
R/W
Set by CRIT0 and CRIT1
0000 0000
Local temp low limit
LTHER
16h
R/W
Set by CRIT0 and CRIT1
0100 0110
Local temp THERM limit
RTH
18h
R/W
Set by CRIT0 and CRIT1
0101 0000
Remote temp high limit
RTL
19h
R/W
Set by CRIT0 and CRIT1
0000 0000
Remote temp low limit
RTHER
1Ah
R/W
Set by CRIT0 and CRIT1
0110 0100
Remote temp THERM limit
LTSD
1Bh
R/W
Set by CRIT0 and CRIT1
N/A
Local temp shutdown limit
(MAX6653 only)
RTSD
1Ch
R/W
Set by CRIT0 and CRIT1
N/A
Remote temp shutdown limit
(MAX6653 only)
Temperature Comparison
and Interrupt System
At the end of each conversion cycle, the converted
temperature data are compared to various set-point
thresholds to control the INT, THERM, SDL, and SDR
outputs. All temperature threshold limits are stored in
the threshold limit registers (Table 6) and can be
changed through the SMBus digital interface.
THERM is an active-low thermal-overload output indicating that the THERM overtemperature set point is exceeded. With the THERM threshold set to an appropriate value,
the THERM output can be used to control clock throttling.
When this pin is pulled low by an external signal, a status
bit (bit 7, status register 2) is set, and the fan speed is
unconditionally forced to full-on speed. The only way to
reset the status bit is to read status register 2. Connect a
10kΩ pullup resistor between THERM and VCC.
_______________________________________________________________________________________
9
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
INT is an open-drain digital output that reports the status of temperature interrupt limits and fan out-of-limit
conditions. Set bit 1 of configuration register 1 (00h) to
1 to enable INT output or reset this bit to zero to disable
the INT output function. Status register 1 contains status information for the conditions that cause INT to
assert. Reading status register 1 resets INT, but INT is
reasserted if the fault condition still exists. Connect a
10kΩ pullup resistor between INT and VCC.
SDL and SDR are open-drain digital outputs on the
MAX6653 that can be used to shut the system down
based on the local (die) temperature of the MAX6653 or
the temperature of the remote sensor, respectively. The
trip thresholds for SDL and SDR are normally set above
the THERM and INT limits. Their power-up values are
set by the CRIT1 and CRIT0 pins, as shown in Table 1.
Fan-Speed Control
The MAX6653/MAX6663/MAX6664 fan-control section
can operate in one of three modes depending on the setting of bit 7 to bit 5 of configuration register 1 (00h).
Regardless of the mode of operation, the PWM output frequency is programmable, and the fan speed is measured
with the result stored in the fan-speed register (08h).
PWM Output Frequency
The PWM output frequency is programmed by bit 5, bit
4, and bit 3 of the fan characteristics register (20h),
regardless of the mode of operation. See Table 7.
Fan-Control Mode
The mode of fan-speed control operation is set by bit 7,
bit 6, and bit 5 in configuration register 1 (00h), as
shown in Table 8.
PWM Duty-Cycle Fan-Control Mode
Bits [3:0] of the fan-speed configuration register set the
PWM duty cycle. See Table 9 for more details.
RPM Select Fan-Control Mode
In RPM select mode, the MAX6653/MAX6663/MAX6664
adjust their PWM output duty cycle to match a selected
fan speed measured by a tachometer count value. Before
selecting this mode by setting bits [7:5] of configuration
register 1 (00h) to 0x1, the desired tachometer count
value should be written to the fan tachometer high-limit
register (10h). In this mode, the MAX6653/MAX6663/
MAX6664 are not able to detect underspeed fan faults
because the fan tachometer high-limit register (10h) functions as the target tachometer count.
The MAX6653/MAX6663/MAX6664 detect fan stall
faults by comparing the fan-speed reading to the fullscale constant of 254 (FEh). Therefore, the
MAX6653/MAX6663/MAX6664 signal a fan fault when
the fan-speed reading is 255 (FFh). Note that the RPM
mode cannot be used for speeds below 10% of the
fan’s maximum speed. It is important to verify that a fan
works properly at lower RPM values if a low-RPM operation in this mode is desired.
Table 7. Setting PWM Output Frequency
FAN CHARACTERISTICS REGISTER
(20H) POR = 011
BIT 5
BIT 4
BIT 3
PWM
FREQUENCY
(Hz)
0
0
0
11.7
0
0
1
15.6
0
1
0
23.4
0
1
1
31.25
1
0
0
37.5
1
0
1
46.9
1
1
0
62.5
1
1
1
93.5
Table 8. Setting the Fan-Speed Control Mode (Default = 100)
Bits [7:5]
MODE OF OPERATION
0x0
PWM duty-cycle mode
10
DESCRIPTION
Directly program the PWM duty cycle by writing to bits [3:0] of the fan-speed
configuration register (22h).
0x1
RPM select mode
Program the desired fan speed by writing to the fan tachometer high-limit register
(10h). This value should be written after selecting the RPM mode. The
MAX6653/MAX6663/MAX6664 then adjust the PWM duty cycle to cause the fan to
spin at the programmed speed.
100
Automatic mode
PWM duty cycle is automatically controlled by the remote temperature.
111
Automatic mode
PWM duty cycle is automatically controlled by both the remote and the local
temperatures. See the Automatic Fan-Control Mode section.
______________________________________________________________________________________
Temperature Monitors and
PWM Fan Controllers
BITS [3:0] OF FAN-SPEED
CONFIGURATION REGISTER (22h)
% DUTY
CYCLE (%)
BIT 3
BIT 2
BIT 1
BIT 0
0
0
0
0
0
0
0
1
7
0
0
1
0
14
0
0
1
1
20
0
1
0
0
27
0
1
0
1
33
0
1
1
0
40
0
1
1
1
47
1
0
0
0
53
1
0
0
1
60
1
0
1
0
67
1
0
1
1
73
1
1
0
0
80
1
1
0
1
87
1
1
1
0
93
1
1
1
1
100
0
Automatic Fan-Control Mode
Automatic fan-speed control is selected by setting bits
[7:5] of configuration register 1 (00h) to 100 (to control
speed based on the remote temperature) or 101 (to
control speed based on both remote and local temperature). Program a threshold, or starting temperature
TMIN, and the desired temperature range, TRANGE, into
the local temp TMIN/TRANGE register (24h) for local
temperature and into the remote temp TMIN/TRANGE
register (25h) for remote temperature (Tables 10 and
11). If the fan control responds to both local and remote
temperatures, the higher PWM duty cycle has priority.
Table 10. TRANGE Fan-Control Temperature
Range Bits [2:0] TMIN/TRANGE Registers
(24h and 25h)—POR = 001
BIT 2
BIT 1
BIT 0
TEMPERATURE
RANGE (°C)
0
0
0
5
0
0
1
10
0
1
0
20
0
1
1
40
1
0
0
80
When the temperature exceeds T MIN , the fan is
enabled at a minimum duty cycle programmed in bits
[3:0] of the fan-speed configuration register (22h). The
duty cycle increases in proportion to the temperature
difference and reaches 100% at a temperature equal to
(TMIN + TRANGE). A hysteresis of 5°C is built into the
TMIN set point to prevent the fan from starting and stopping when the temperature is at the set point.
Spin-Up
To ensure proper fan startup, the MAX6653/MAX6663/
MAX6664 can be set to drive the fan to 100% duty
cycle for a short period on startup, and then revert to
the correct duty cycle. The spin-up time is programmed
by bits [2:0] in the fan characteristics register (20h).
The spin-up feature can be disabled by setting bit 7 of
the fan-filter register (23h) to 1; POR value is zero.
Table 12 shows programming of the spin-up time.
Fan-Filter Mode
When the MAX6653/MAX6663/MAX6664 are used for
automatic fan-speed control, the fan-filter mode helps
minimize the audible effects of varying fan speeds. The
fan-filter mode limits the rate at which fan speed can
change. Each time a new temperature measurement is
made, the fan-filter mode allows the PWM duty cycle to
increment by a selectable amount. The duty cycle can
change by 1/240, 2/240, 4/240, or 8/240 (0.416%,
0.833%, 1.667%, or 3.333%) of the PWM period after
each temperature-monitoring cycle. This prevents sudden changes in fan speed, even when temperature
changes suddenly.
The filter mode is set by bit 0 of the fan-filter register
(23h). To enable the fan-filter mode, write a 1 to this bit.
Bits [6:5] of the same register control the size of the
PWM steps.
Note that the rate of change depends on both the value
selected by the fan-filter bits and on the temperature
Table 11.TMIN Fan-Control Start
Temperature; Bits [7:3] TMIN/TRANGE
Registers (24h—POR = 01000 and
25h—POR = 01100
BIT 7
BIT 6
BIT5
BIT 4
MSB = +64°C
BIT3
LSB = +4°C
Min threshold = 0°C
Max threshold = +127°C
LSB/step size = +4°C
POR = +48°C or 01100b
______________________________________________________________________________________
11
MAX6653/MAX6663/MAX6664
Table 9. Setting PWM Duty Cycle
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
Table 12. Spin-Up Time; Bits [2:0] Fan
Characteristics Register (20h)—POR = 101
BIT 2
BIT 1
BIT 0
SPIN-UP
TIME (s)
0
0
0
0.2
0
0
1
0.4
0
1
0
0.6
0
1
1
0.8
1
0
0
1
1
0
1
2
1
1
0
4
1
1
1
8
Table 13. Fan Filter Ramp Rate; Bits [6:5]
Fan Filter Register (23h)—POR = 10;
BIT 6
BIT 5
RAMP RATE
(x100% / 240)
RAMP RATE
(% DUTY CYCLE)
0
0
1
0.416
0
1
2
0.833
1
0
4
1.667
1
1
8
3.333
measurement rate, which is controlled by bits [4:2] of
the fan-filter register (23h). Table 5 shows the effect of
the temperature measurement rate control bits. As an
example, assume that the temperature measurement
rate is 2Hz, or 0.5s per monitoring cycle, and the fan-filter rate is 0.416% per monitoring cycle. For the fan drive
to change from 50% to 100% requires 50% / 0.416% =
120 temperature monitoring cycles. Thus, for a temperature-monitoring cycle of 0.5s, the time required for the
drive to change from 50% to 100% is 60s.
clock frequency into a fan-speed counter. The measurement is initialized on the starting edge of a PWM
output if fan-speed measurement is enabled by setting
bit 2 of configuration register 2 (01h) to 1. Counting
begins on the leading edge of the second tachometer
pulse and lasts for two tachometer periods or until the
counter overranges (255). The measurement repeats
unless monitoring is disabled by resetting bit 2 in the
configuration register 2 (01h). The measured result is
stored in the fan-speed reading register (08h).
The fan-speed count is given by:
The fan-speed count is given675
by:,000
Count =
RPM × N
where RPM = fan speed in RPM.
N determines the speed range and is programmed by
bits [7:6] in the fan characteristics register (20h) as
shown in Table 14. When the speed falls below the value
in the speed range column, a fan failure is detected.
The TACH/AIN input can be either a digital signal (from
the fan’s tachometer output) or an analog signal,
depending on the setting of bit 2 of the configuration
register 1 (00h). The default setting is zero, which sets
up TACH/AIN as a digital input. For the analog input
(Figure 4), the detected voltage threshold is typically at
250mV, which is appropriate for sensing the voltage of
a sense resistor connected to the ground lead of a 2wire fan. The AIN input only responds to pulse widths
greater than 10µs.
TACH
INPUT
0.1µF
VREF 1
Fan-Speed Measurement
The fan speed is measured by using the relatively slow
tachometer signal from the fan to gate an 11.25kHz
FF
100Ω
VREF 2
MAX6653
MAX6663
MAX6664
CLK
Figure 4. Simplified Tachometer Analog Input Structure
Table 14. N Factor for Speed-Range Adjustment (Assuming Two Tachometer Pulses
per Revolution)
FAN CHARACTERISTICS REGISTER (20h) POR = 01
12
N
SPEED RANGE (FAIL SPEED)
(RPM)
0
1
2647
0
1
2
1324
1
0
4
662
1
1
8
331
BIT 7
BIT 6
0
______________________________________________________________________________________
Temperature Monitors and
PWM Fan Controllers
Fan-Fault Detection
The FAN_FAULT output is used to indicate fan slow
down or failure. POR disables the FAN_FAULT output
on the MAX6653/MAX6663. POR enables FAN_FAULT
output on the MAX6664. If FAN_FAULT is not enabled,
writing a logic 1 to bit 4 of configuration register 1 (00h)
enables the FAN_FAULT output pin. Either underspeed or stalled fans are detected as fan faults.
FAN_FAULT is asserted low only when five consecutive
interrupts are generated by the MAX6653/MAX6663/
MAX6664s’ INT due to fan faults. The MAX6653/
MAX6664 apply 100% duty cycle for the duration of the
spin-up time once an INT is asserted. The MAX6663
goes to 100% duty cycle for the duration of the spin-up
time once INT is asserted and status register 1 is read.
Fan-fault detection works by comparing the value of the
fan tachometer high-limit register (10h) with the value of
the fan-speed reading register (08h), which contains the
value of the most recent fan-speed measurement. Note
that the value of the fan-speed reading register (08h)
must exceed the value of the fan tachometer high limit
(10h) by 1 in order to qualify as a fault. The fault generates an interrupt signal by asserting the INT output, but
does not cause the FAN_FAULT output to assert until five
consecutive failures have been detected. The fan runs at
100% duty cycle when five consecutive failures have
been detected, whether FAN_FAULT is enabled or not.
As an example of the function of the fan-fault detection,
assume a fan is stalled or under speed. The MAX6663 initially indicates the failure by generating an interrupt on the
INT pin. The fan fault bit (bit 1) of interrupt status register
1 (02h) is also set to 1. Once the processor has acknowledged the INT by reading status register 1, the INT is
cleared. PWM_OUT is then brought high for a 2s (fan
5V
3.3V
2-WIRE
FAN
100Ω
(TYP)
PWM_OUT
MAX6653
MAX6663
MAX6664
N
NDT3055L
C1
TACH/AIN
2Ω
RSENSE
Figure 5. Using the MAX6653/MAX6663/MAX6664 with a
2-Wire Fan
spin-up default, Table 12) spin-up period to restart the
fan. Subsequent fan failures cause INT to be reasserted
and PWM_OUT to be brought high (following a status
register 1 read) for a spin-up period each time to restart
the fan. Once the fifth tachometer failure occurs, the
FAN_FAULT is asserted to indicate a critical fan failure.
A MAX6653/MAX6664 example is somewhat simpler.
Again assume the fan is stalled or under speed. The
MAX6653/MAX6664 initially indicate the failure by generating an interrupt on the INT pin. The fan fault bit of the
interrupt status register is set to 1. PWM_OUT goes high
for the programmed spin-up time (2s default) to restart
the fan. Each subsequent fan failure causes another spinup. Once the fifth tachometer failure occurs, the
FAN_FAULT output is asserted (if enabled) and the PWM
output is driven to 100%.
When the FAN_FAULT output is disabled (register 00h,
bit 4), spin-ups are still attempted whenever the tach
count is greater than the value in the fan tachometer
high-limit register (10h). If fan faults and their associated spin-ups are not desired, the fan tachometer highlimit register (10h) to FF. This prevents the tach count
from ever exceeding the limit and faults are not detected. Simply disabling the tachometer input (register 01h,
bit 2) leaves the fan fault function enabled and can
result in fan faults.
______________________________________________________________________________________
13
MAX6653/MAX6663/MAX6664
Figure 5 shows a schematic using a current-sensing
resistor and a coupling capacitor to derive the
tachometer information from the power-supply current
of a 2-wire fan. This circuit allows the speed of a 2-wire
fan to be measured even though the fan has no
tachometer signal output. The sensing resistor,
RSENSE, converts the fan commutation pulses into a
voltage and this voltage is AC-coupled into the
TACH/AIN input through coupling capacitor C1. The
value of RSENSE is on the order of 1Ω to 5Ω, depending
on the fan, and the value of the coupling capacitor C1
is 0.01µF. When using this method, set bit 2 of configuration register 1 to 1.
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
Alarm Speed
memory buses, and ISA/PCI buses.
For the MAX6663, the alarm speed bit, bit 0 of status
register 1 (02h), indicates that the PWM duty cycle is
100%, excluding the case of fan spin-up. For the
MAX6653/MAX6664, this bit indicates that the THERM
output is low. Once this bit is set, the only way to clear it
is by reading status register 1. However, the bit does
not reassert on the next monitoring cycle if the condition still exists. It does assert if the condition is discontinued and then returns.
2) Do not route the DXP-DXN lines next to the deflection coils of a CRT. Also, do not route the traces
across fast digital signals, which can easily introduce 30°C error, even with good filtering.
3) Route the DXP and DXN traces in parallel and in
close proximity to each other, away from any higher
voltage traces, such as 12VDC. Leakage currents
from PC board contamination must be dealt with
carefully since a 20MΩ leakage path from DXP to
ground causes about 1°C error. If high-voltage traces
are unavoidable, connect guard traces to GND on
either side of the DXP-DXN traces (Figure 6).
Power-On Default Conditions
At power-up, the MAX6653/MAX6663/MAX6664 are
monitoring temperature to protect the system against
thermal damage. The PWM outputs are in known states.
Note that although the "Monitoring" bit (Configuration
register 1, Bit 0) is enabled, automatic fan speed control
does not begin until a 1 is rewritten to Bit 0.
Other default conditions as listed in the Register Summary
section.
4) The 10-mil widths and spacing recommended in
Figure 6 are not absolutely necessary, as they offer
only a minor improvement in leakage and noise over
narrow traces. Use wider traces when practical.
5) Add a 200Ω resistor in series with VCC for best
noise filtering (see Typical Operating Circuits).
After applying power to the MAX6653/MAX6663/
MAX6664, set the desired operating characteristics (fan
configuration, alarm thresholds, etc.). Write to
Configuration register 1 last. When a 1 is first written to
Bit 0 of this register, fan control will commence as
determined by the register contents.
GND
10 MILS
PC Board Layout
10 MILS
DXP
10 MILS
DXN
Follow these guidelines to reduce the measurement
error of the temperature sensors:
MINIMUM
1) Place the MAX6653/MAX6663/MAX6664 as close
as is practical to the remote diode. In noisy environments, such as a computer motherboard, this distance can be 4in to 8in (typ). This length can be
increased if the worst noise sources are avoided.
Noise sources include CRTs, clock generators,
10 MILS
GND
Figure 6. Recommended DXP/DXN PC Traces
Table 15. Power-On Default Conditions
MAX6653
MAX6663
MAX6664
Temperature Monitoring
Monitoring at 4Hz
Monitoring at 4Hz
Monitoring at 4Hz
PWM Output
Low
High
High
PWM Mode
PWM duty cycle control mode
PWM duty cycle control mode
Automatic fan speed control mode
Duty cycle setting (not
enabled until a 1 is written
to Bit 0 of Register 00h)
33%
100%
Automatic
PWM Polarity
Inverted
(100% duty cycle = output high)
Not Inverted
(100% duty cycle = output low)
Not Inverted
(100% duty cycle = output low)
14
______________________________________________________________________________________
Temperature Monitors and
PWM Fan Controllers
Addr(H)
READ/WRITE POR STATE
MAX6653
0000 1001
00
R/W
MAX6663
00000001
MAX6664
10010001
01
R/W
0111 1111
DESCRIPTION
Configuration register 1:
Bits [7:5]: Setting the fan-speed control mode:
Bit 7 = 1: Enables automatic fan-speed control mode.
Bits [6:5] = 00: Remote temperature controls the fan speed.
Bits [6:5] =11: Both remote and local temperature control the fan speed.
Bit 7 = 0, Enables PWM control mode or RPM control mode.
Bits [6:5] = X0: PWM duty cycle control mode.
Bits [6:5] = X1: RPM control mode.
Bit 4: FAN_FAULT output enable:
1: FAN_FAULT output enabled; 0: (default) FAN_FAULT output disabled.
Bit 3: Invert the PWM output:
0: (default) PWM active low; 1: (inverted) PWM active high.
Bit 2: TACHOMETER digital/analog input selection:
0: (default) TACHOMETER is a logic input; 1: TACHOMETER is an analog input.
Bit 1: INT output enable:
0: INT output disabled; 1: INT output enabled.
Bit 0: Monitoring:
0: sleep mode; 1: (default) active temperature monitoring and fan-speed control.
(Keep this bit set to 1 for MAX6663.) Although the default value of this bit is 1, fan
speed control for the MAX6653 and MAX6664 is inactive until a 1 is written
to this bit.
Configuration register 2:
Bit 7: Reset:
Setting this bit to 1 restores all registers to POR default states; self-clears to zero
after reset.
Bit 6: Unused.
Bit 5: Remote temperature enable:
0: interrupts disabled for remote channel; 1: interrupts enabled for remote
channel; defaults to 1 unless a diode fault is detected on power-up.
Bit 4: Local temperature enable:
0: interrupts disabled for local channel; 1: (default) interrupts enabled for local
channel.
Bit 3: INT input function mask:
0: enable INT input function; 1: (default) disable INT input function.
Bit 2: TACHOMETER input enable:
0: disable TACHOMETER input; 1: (default) enable the TACHOMETER input.
(Keep this bit set to 1 for MAX6663.)
Bit 1: SMBus timeout enable:
0: SMBus timeout disabled; 1: (default) SMBus timeout enabled.
Bit 0: PWM out enable:
0: PWM output disabled; 1: (default) PWM output enabled.
______________________________________________________________________________________
15
MAX6653/MAX6663/MAX6664
Register Summary
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
Register Summary (continued)
Addr(H)
02
03
16
READ/WRITE POR STATE
R
R
DESCRIPTION
0000 0000
Status register 1:
Bit 7: Local temp low:
1: Local temp low interrupt limit has been exceeded. This bit is cleared by
reading status register 1 for the MAX6653/MAX6663/MAX6664 or completing an
alert response protocol for the MAX6664. This bit is asserted on the next cycle if
the local temperature is still less than the limit.
Bit 6: Local temp high:
1: Local temp high interrupt limit has been exceeded. This bit is cleared by
reading status register 1 for the MAX6653/MAX6663/MAX6664 or completing an
alert response protocol for the MAX6664. This bit is asserted on the next cycle if
the local temperature is still greater than the limit.
Bit 5: Remote-diode error:
1: remote-diode short circuit or open circuit detected.
Bit 4: Remote temp THERM:
1: Remote temp THERM limit has been exceeded. This bit is cleared by reading
status register 1.
Bit 3: Remote temp low:
1: Remote temp low interrupt limit has been exceeded. This bit is cleared by
reading status register 1 for the MAX6653/MAX6663/MAX6664 or completing an
alert response protocol for the MAX6664. This bit is asserted on the next cycle if
the remote temperature is still less than the limit.
Bit 2: Remote temp high:
1: Remote temp high interrupt limit has been exceeded. This bit is cleared by
reading status register 1 for the MAX6653/MAX6663/ MAX6664 or completing an
alert response protocol for the MAX6664. This bit is asserted on the next cycle if
the remote temperature is still greater than the limit.
Bit 1: Fan fault:
1: The fan is running under speed. This bit is cleared by reading status register 1
or completing an alert response protocol. This bit is asserted again on the next
cycle if the fan fault still exists.
Bit 0: Alarm speed:
For MAX6663, this bit is set to 1 when the PWM duty cycle = 100%. Once read,
this bit does not reassert on the next monitoring cycle, even if the condition still
exists. It is asserted again if the condition is discontinued and then returns. For
the MAX6653/MAX6664, this bit is set to 1 when the THERM output goes to low.
0000 0000
Status register 2:
Bit 7: THERM:
1: THERM has been pulled low externally. This bit clears on a read of status
register 2.
Bit 6: Local temp THERM:
1: Local temp THERM limit has been exceeded. This bit is cleared by reading
status register 2.
Bits [5:0]: Unused.
06
R
0000 0000
Extended bits of temperature data:
Bits [7:5]: Extended bits for local temperature data.
Bits [4:3]: Unused.
Bits [2:0]: Extended bits for remote temperature data.
08
R
1111 1111
Fan-speed reading register:
This register contains the fan-speed tachometer measurement.
______________________________________________________________________________________
Temperature Monitors and
PWM Fan Controllers
Addr(H)
READ/WRITE POR STATE
DESCRIPTION
0A
R
0001 1110
(30°C)
Local temperature data:
This register contains the 8 MSBs of the local temperature measurement.
0B
R
0001 1110
(30°C)
Remote temperature data:
This register contains the 8 MSBs of the local temperature measurement.
0000 0000
Local temperature offset:
Bit 7: Sign bit; when zero, the offset value in bits [3:0] is added to the measured local
temperature reading. When this bit is 1, the offset value in bits [3:0] is subtracted
from the local temperature reading.
Bits [6:4] Unused. This bits normally reads back zeros.
Bits [3:0] Offset value. This is added to or subtracted from the measured local
temperature reading.
0D
R/W
0E
R/W
0000 0000
Remote temperature offset:
Bit 7: Sign bit: When 0, the offset value in bits [3:0] is added to the measured remote
temperature reading. When this bit is 1, the offset value in bits [3:0] is subtracted
from the remote temperature reading.
Bits [6:4] Unused: These bits normally read back zeros.
Bits [3:0] Offset value: This is added to or subtracted from the measured remote
temperature reading.
10
R/W
1111 1111
Fan tachometer high-limit register:
Contains the limit of the fan-speed measurement. It detects a stalled fan if the
measured fan-speed data (reg_08h; proportional to fan period) is larger than the limit.
14
R/W
0011 1100
(60°C)
Local temp high limit:
Contains the local high-temperature interrupt limit.
15
R/W
0000 0000
(0°C)
Local temp low limit:
Contains the local low-temperature interrupt limit.
16
R/W
0100 0110
(70°C)
Local temp THERM limit:
Contains the local high-temperature limit for the THERM output. Default is +70°C for
the MAX6663/MAX6664; CRIT0 and CRIT1 determine the default value for the
MAX6653 (see Table 1).
18
R/W
0101 0000
(80°C)
Remote temp high limit:
Contains the remote high-temperature interrupt limit.
19
R/W
0000 0000
(0°C)
Remote temp low limit:
Contains the remote low-temperature interrupt limit.
1A
R/W
0110 0100
(100°C)
Remote temp THERM limit:
Contains the remote high-temperature limit for the THERM output. Default is +100°C
for the MAX6663/MAX6664; CRIT0 and CRIT1 determine the default value for the
MAX6653 (see Table 1).
1B
R/W
0101 1111
(95°C)
Local temp shutdown limit:
Contains the local high-temperature limit for the SDL output. CRIT0 and CRIT1
determine the default value for the MAX6653 (see Table 1).
1C
R/W
0111 1101
(125°C)
Remote temp shutdown limit:
Contains the remote high-temperature limit for the SDR output. CRIT0 and CRIT1
determine the default value for the MAX6653 (see Table 1).
______________________________________________________________________________________
17
MAX6653/MAX6663/MAX6664
Register Summary (continued)
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
Register Summary (continued)
Addr(H)
20
READ/WRITE POR STATE
R/W
0101 1101
MAX6653/
MAX6664
22
R/W
01010101
MAX6663
01011111
18
DESCRIPTION
Fan characteristics register:
Bits [7:6]: N factor:
These bits contain the N factor for the fan-speed range:
00 = 1 (fail speed =2647RPM)
01 = 2 (fail speed =1324RPM) (default)
10 = 4 (fail speed = 662RPM)
11 = 8 (fail speed = 331RPM)
Bits [5:3]: PWM frequency:
These bits contain the nominal PWM output frequency:
000 = 11.7Hz
001 = 15.6Hz
010 = 23.4Hz
011 = 31.25Hz (default)
100 = 37.5Hz
101 = 46.9Hz
110 = 62.5Hz
111 = 93.5Hz
Bits [2:0]: Spin-up:
These bits contain the fan spin-up time:
000 = 200ms
001 = 400ms
010 = 600ms
011 = 800ms
100 = 1s
101 = 2s (default)
110 = 4s
111 = 8s
Fan-speed configuration register:
Bits [7:4]: Unused.
Bits [3:0]: PWM duty cycle: These bits contain the PWM duty cycle for the PWM duty
cycle fan-control mode. They also contain the minimum duty cycle that is
applied to the fan:
0000 = 0% output
0001 = 7% output
0010 = 14% output
0011 = 20% output
0100 = 27% output
0101 = 33% output (default)
0110 = 40% output
0111 = 47% output
1000 = 53% output
1001 = 60% output
1010 = 67% output
1011 = 73% output
1100 = 80% output
1101 = 87% output
1110 = 93% output
1111 =100% output
______________________________________________________________________________________
Temperature Monitors and
PWM Fan Controllers
Addr(H)
READ/WRITE POR STATE
23
R/W
0101 1101
24
R/W
0100 0001
25
R/W
0110 0001
DESCRIPTION
Fan filter register:
Bit 7: Fan spin-up disable:
0: Spin-up enabled; 1: spin-up disabled.
Bits [6:5]: Fan ramp rate: These bits set the amount the PWM duty cycle can change
on each monitoring cycle:
00 = 1 (0.416%)
01 = 2 (0.833%)
10 = 4 (1.667%) (default)
11 = 8 (3.333%)
Bits [4:2]: Temperature measurement rate (see Table 5).
Bit 1: Unused.
Bit 0: Fan filter enable. Setting the bit to 1 enables the fan filter function.
Local temp TMIN/ TRANGE register:
Bits [7:3]: Local TMIN: Contains the temp threshold for the automatic fan-speed control
mode. When the local temperature exceeds this value, the PWM output
becomes active:
00000 = 00C
00001 = +40C
|
01000 = +320C (default)
|
11110 = +1200C
11111 = +1240C
Bits [2:0]: Local TRANGE: Contains the local temperature range for automatic fanspeed control mode. When the temperature reaches TMIN + TRANGE, the
PWM duty cycle reaches 100%:
000 = +50C
001 = +100C (default)
010 = +200C
011 = +400C
100 = +800C
Remote temp TMIN/TRANGE register:
Bits [7:3]: Remote TMIN. Contains the temp threshold for the automatic fan-speed
control mode. When the remote temperature exceeds this value, the PWM
output becomes active.:
00000 = 00C
00001 = +40C
|
01100 = +480C (default)
|
11110 = +1200C
1111 = +1240C
Bits [2:0]: Remote TRANGE: Contains the remote temperature range for automatic fanspeed control mode. When the temperature reaches TMIN + TRANGE, the
PWM duty cycle reaches 100%:
000 = +50C
001 = +100C (default)
010 = +200C
011 = +400C
100 = +800C
______________________________________________________________________________________
19
MAX6653/MAX6663/MAX6664
Register Summary (continued)
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
Register Summary (continued)
Addr(H)
READ/WRITE POR STATE
DESCRIPTION
3D
R
0011 1000
Device ID
3E
R
0100 1101
Manufacturer ID
1000 0000
THERM behavior/revision:
Bit [7]: THERM behavior:
1: enable THERM as an output.
0: disable THERM as an output.
Bits [3:0] revision number.
*For MAX6663 bit 7 has to be 1 all the time.
3F
R/W
Twisted-Pair and Shielded Cables
Use a twisted-pair cable to connect the remote sensor
for remote-sensor distances longer than 8in, or in very
noisy environments. Twisted-pair cable lengths can be
between 6ft and 12ft before noise introduces excessive
errors. For longer distances, the best solution is a
shielded twisted pair like that used for audio microphones. For example, Belden 8451 works well for distances up to 100ft in a noisy environment. At the
device, connect the twisted pair to DXP and DXN and
the shield to GND. Leave the shield unconnected at the
remote sensor. For very long cable runs, the cable’s
parasitic capacitance often provides noise filtering, so
the 2200pF capacitor can often be removed or reduced
in value.
Cable resistance also affects remote-sensor accuracy.
For every 1Ω of series resistance, the error is approximately 0.5°C.
PC Board Layout Checklist
•
Place the MAX6653/MAX6663/MAX6664 close to
the remote-sense junction.
•
Keep traces away from high voltages (+12V bus).
•
Keep traces away from fast data buses and CRTs.
•
Use recommended trace widths and spacings.
•
Place a ground plane under the traces.
•
Use guard traces flanking DXP and DXN and connecting to GND.
•
Place the noise filter and the 0.1µF VCC bypass
capacitors close to the MAX6653/MAX6663/
MAX6664.
20
Table 16. Remote-Sensor Transistor
Manufacturers
MANUFACTURER
MODEL NO.
Central Semiconductor (USA)
CMPT3904
Rohm Semiconductor (USA)
SST3904
Samsung (Korea)
KST3904-TF
Siemens (Germany)
SMBT3904
Zetex (England)
FMMT3904CT-ND
Note: Discrete transistors must be diode connected (base
shorted to collector).
Remote Diode Considerations
The accuracy of the remote temperature measurements
depends on the ideality factor (n) of the remote “diode”
(actually a transistor). The MAX6653/MAX6663/
MAX6664 are optimized for n = 1.008, which is the typical value for the Intel Pentium III. A thermal diode on
the substrate of an IC is normally a PNP with its collector grounded. DXP should be connected to the anode
(emitter) and DXN should be connected to the cathode
(base) of this PNP.
When the remote-sensing diode is a discrete transistor,
its collector and base should be connected together.
Table 16 lists examples of discrete transistors that are
appropriate for use with the MAX6653/MAX6663/
MAX6664.
The transistor must be a small-signal type with a relatively high forward voltage; otherwise, the A/D input
voltage range can be violated. The forward voltage at
______________________________________________________________________________________
Temperature Monitors and
PWM Fan Controllers
Manufacturers of discrete transistors do not normally
specify or guarantee ideality factor. This is normally not
a problem since good-quality discrete transistors tend
to have ideality factors that fall within a relatively narrow
range. We have observed variations in remote temperature readings of less than ±2°C with a variety of discrete transistors. Still, it is sound design practice to
verify good consistency of temperature readings with
several discrete transistors from any manufacturer
under consideration.
Typical Operating Circuits
+3.3V
+5V
+3.3V
3-WIRE
FAN
10kΩ
2.2kΩ
+3.3V
+3.3V
2.2kΩ
CLOCK
10kΩ
1
PWM_OUT
SMBCLK
TACH/AIN
SMBDATA
DATA
16
NDT3055L
+3.3V
2
15
10kΩ
3
+3.3V
CRIT0
INT
INTERRUPT
TO µC
14
+3.3V
4
CRIT1
MAX6653
ADD
13
10kΩ
5
GND
SDR
12
SYSTEM
SHUTDOWN
+3.3V
6
VCC
SDL
THERM
DXP
11
10kΩ
THERM SIGNAL
TO THROTTLE
CPU CLOCK
7
CPU
10
+3.3V
2.2nF
10kΩ
FAN _FAULT
TO SIGNAL
FAN-FAILURE
CONDITION
8
FAN_FAULT
DXN
9
______________________________________________________________________________________
21
MAX6653/MAX6663/MAX6664
the highest expected temperature must be greater than
0.25V at 10µA, and at the lowest expected temperature, the forward voltage must be less than 0.95V at
100µA. Large power transistors must not be used. Also,
ensure that the base resistance is less than 100Ω. Tight
specifications for forward current gain (50 < ß <150, for
example) indicate that the manufacturer has good
process controls and that the devices have consistent
VBE characteristics.
Temperature Monitors and
PWM Fan Controllers
MAX6653/MAX6663/MAX6664
Typical Operating Circuits (continued)
+3.3V
+5V
+3.3V
3-WIRE
FAN
10kΩ
2.2kΩ
+3.3V
+3.3V
2.2kΩ
CLOCK
10kΩ
1
PWM_OUT
SMBCLK
TACH/AIN
SMBDATA
DATA
16
NDT3055L
+3.3V
2
15
10kΩ
3
N.C.
INT
INTERRUPT
TO µC
14
+3.3V
4
+3.3V
5
N.C.
GND
MAX6663
MAX6664
ADD
N.C.
13
12
+3.3V
6
VCC
N.C.
THERM
DXP
11
10kΩ
THERM SIGNAL
TO THROTTLE
CPU CLOCK
7
CPU
10
+3.3V
2.2nF
10kΩ
FAN _FAULT
TO SIGNAL
FAN-FAILURE
CONDITION
22
8
FAN_FAULT
DXN
9
______________________________________________________________________________________
Temperature Monitors and
PWM Fan Controllers
VCC
TACH SIGNAL
CONDITIONING
TACH/AIN
SMBCLK
SMBus
INTERFACE
SLAVE ADDRESS
DECODER
ADD
SMBDATA
TACHOMETER
REGISTER BANK
DXP
ANALOG
MUX
DXN
ADC
INTERNAL
TEMPERATURE
SENSOR
PWM_OUT
TEMPERATURE
MEASUREMENT
BANDGAP
REFRENCE
(CRIT1)
SHUTDOWN AND
THERM LIMIT
DECODER
MUX
(CRIT0)
INT
THERM
FAN_FAULT
(SDL)
(SDR)
PWM OUTPUT CONTROLLER
ALU
( ) ARE FOR MAX6653 ONLY
GND
Pin Configurations (continued)
Chip Information
TRANSISTOR COUNT: 27,074
PROCESS: BiCMOS
TOP VIEW
PWM_OUT 1
16 SMBCLK
TACH/AIN 2
15 SMBDATA
N.C. 3
N.C. 4
GND 5
14 INT
MAX6663
MAX6664
13 ADD
12 N.C.
VCC 6
11 N.C.
THERM 7
10 DXP
FAN_FAULT 8
9
DXN
QSOP
______________________________________________________________________________________
23
MAX6653/MAX6663/MAX6664
Functional Diagram
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
QSOP.EPS
MAX6653/MAX6663/MAX6664
Temperature Monitors and
PWM Fan Controllers
PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH
21-0055
E
1
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.