19-1574; Rev 0; 1/00
Fan Controller and Remote Temperature Sensor
with SMBus Serial Interface
General Description
The MAX1669 fan controller includes a precise digital
thermometer that reports the temperature of a remote
sensor. The remote sensor is a diode-connected transis-
tor—typically a low-cost, easily mounted 2N3906 PNP
type—replacing conventional thermistors or thermocou-
ples. Remote accuracy is ±3°C for transistors from multi-
ple manufacturers, with no calibration needed. The
MAX1669 has an independent fan controller with a low-
current logic output requiring external power compo-
nents to interface to a DC brushless fan. The fan
controller has two modes of operation: a low-frequency
(20Hz to 160Hz) PWM mode intended for driving the fan
motor, or a high-impedance DAC output that generates
a variable DC control voltage. In PWM mode, the FAN
frequency can be synchronized to an external clock.
Other key features include general-purpose inputs/out-
puts (GPIOs) for fan presence detection and a thermo-
stat output intended as a fan override signal in case the
host system loses the ability to communicate. The inter-
nal ADC has a wide input voltage range and gives
overrange readings when too large an input voltage is
applied. Other error-checking includes temperature
out-of-range indication and diode open/short faults.
The MAX1669 is available in a space-saving 16-pin
QSOP package that allows it to fit adjacent to the
SLOT1 connector.
PART
Features
o
Measures Remote CPU Temperature
o
No Calibration Required
o
20Hz to 160Hz PWM Output for Fan
o
PWM Frequency Sync Input (260kHz)
o
Flexible Fan Interface: Linear or PWM
o
SMBus 2-Wire Serial Interface
o
Programmable Under/Overtemperature Alarms
o
ALERT
Latched Interrupt Output
o
OVERT
Thermostat Output
o
Two GPIO Pins
o
Write-Once Configuration Protection
o
Supports SMBus Alert Response
o
±3°C Temperature Accuracy (-40°C to +125°C,
remote)
o
3µA Standby Supply Current
o
+3V to +5.5V Supply Range
o
Small 16-Pin QSOP Package
MAX1669
Ordering Information
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
16 QSOP
MAX1669EEE
Applications
Pentium
®
CPU Cooling
Desktop Computers
Notebook Computers
Servers
Workstations
Pin Configuration
TOP VIEW
I/O1 1
I/O2 2
16 OVERT
15 ALERT
14 SMBDATA
Typical Operating Circuit appears at end of data sheet.
ADD0 3
ADD1 4
ADD2 5
AGND 6
DXN 7
DXP 8
MAX1669
13 SMBCLK
12 PGND
11 FAN
10 SYNC
9
V
CC
QSOP
Pentium is a registered trademark of Intel Corp.
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
Fan Controller and Remote Temperature Sensor
with SMBus Serial Interface
MAX1669
ABSOLUTE MAXIMUM RATINGS
V
CC
to AGND...........................................................-0.3V to +6V
DXP, ADD_ to AGND.................................-0.3V to (V
CC
+ 0.3V)
DXN to AGND.......................................................-0.3V to +0.8V
SMBCLK, SMBDATA,
ALERT,
SYNC,
I/O1, I/O2,
OVERT,
FAN to AGND ......................-0.3V to +6V
FAN to PGND ............................................-0.3V to (V
CC
+ 0.3V)
PGND to AGND ....................................................-0.3V to +0.3V
PWM Current....................................................-50mA to +50mA
SMBDATA Current .............................................-1mA to +50mA
I/O1, I/O2 Current...............................................-1mA to +25mA
DXN Current ......................................................................±1mA
ESD Protection (all pins, Human Body Model) .................2000V
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.30mW/°C above +70°C).......667mW
Operating Temperature Range (extended) ......-55°C to +125°C
Junction Temperature .....................................................+150°C
Storage Temperature Range ............................-65°C to +150°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
(V
CC
= +3.3V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
ADC AND POWER SUPPLY
Resolution (Note 1)
Temperature Error, Remote Diode (Note 2)
Supply Voltage Range
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
Power-On Reset Threshold
POR Threshold Hysteresis
Standby Supply Current
SMBus static
SMBCLK at 10kHz
Autoconvert mode,
average measured over 1s FAN output set to
DAC mode
From stop bit to conversion complete
Autoconvert mode
V
DXP
forced to V
DXN
+ 0.65V
High level
Low level
47
1.6
80
8
FAN output set to
150Hz mode
V
CC
, falling edge
1
V
CC
input, disables A/D conversion,
rising edge
Monotonicity guaranteed
T
R
= 0°C to +100°C, diode ideality factor = 1.013
8
-3
3
2.6
2.8
50
1.9
50
3
3
75
360
62
2
100
10
0.7
PWM mode, V
FAN
forced to 2.9V
PWM mode, V
FAN
forced to 0.4V
10
-10
78
2.4
120
12
150
10
2.5
3
5.5
2.95
Bits
°C
V
V
mV
V
mV
µA
µA
µA
ms
Hz
µA
V
mA
mA
CONDITIONS
MIN
TYP
MAX
UNITS
Average Operating Supply Current
Conversion Time
Conversion Rate
Remote-Diode Source Current
DXN Source Voltage
FAN OUTPUT
FAN Output Source Current
FAN Output Sink Current
2
_______________________________________________________________________________________
Fan Controller and Remote Temperature Sensor
with SMBus Serial Interface
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.3V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
FAN PWM Frequency Error
FAN Total Unadjusted Error
FAN Output Voltage High
FAN Output Voltage Low
SYNC Capture Range
SYNC Input High Period
SYNC Input Low Period
SMBus INTERFACE
(Figures 7, 8)
Logic Input High Voltage
Logic Input Low Voltage
SMBDATA,
ALERT, OVERT,
I/O1, I/O2
Output Low Sink Current
ALERT, OVERT,
I/O1, I/O2 Output
High Leakage Current
Logic Input Current
SMBus Input Capacitance
SMBus Clock Frequency
SMBCLK Clock Low Time (t
LOW
)
SMBCLK Clock High Time (t
HIGH
)
SMBus Rise Time
SMBus Fall Time
SMBus Start Condition Setup Time
SMBus Repeated Start Condition Setup
Time (t
SU:STA
)
SMBus Start Condition Hold Time (t
HD:STA
)
SMBus Data Valid to SMBCLK
Rising-Edge Time (t
SU:DAT
)
SMBus Data-Hold Time (
t
HD:DAT
)
SMBus Bus-Free Time (t
BUF
)
SMBCLK Falling Edge to SMBus
Data-Valid Time
90% to 90% points
10% of SMBDATA to 90% of SMBCLK
ADD_, I/O1, I/O2, SYNC, SMBCLK, SMBDATA;
V
CC
= 3V to 5.5V
ADD_, I/O1, I/O2, SYNC, SMBCLK, SMBDATA;
V
CC
= 3V to 5.5V
Pin forced to 0.4V
Pin forced to 5.5V
Logic inputs forced to V
CC
or GND
SMBCLK, SMBDATA
(Note 3)
10% to 10% points
90% to 90% points
SMBCLK, SMBDATA, 10% to 90% points
SMBCLK, SMBDATA, 90% to 10% points
4.7
500
4
4
250
0
4.7
1
DC
4.7
4
1
300
-1
5
100
6
1
1
2.1
0.8
V
V
mA
µA
µA
pF
kHz
µs
µs
µs
ns
µs
ns
µs
µs
ns
µs
µs
µs
CONDITIONS
PWM mode, any setting
DAC mode, any setting, R
L
= 10kΩ to GND
DAC mode, FAN duty factor = 1111b,
I
OUT
= 5mA
DAC mode, FAN duty factor = 0000b,
I
OUT
= -5mA
140
500
500
MIN
-20
-4
2.96
3.06
0.05
260
0.2
400
TYP
MAX
+20
4
UNITS
%
%FS
V
V
kHz
ns
ns
MAX1669
SMBus Stop Condition Setup Time (t
SU:STO
) 90% of SMBCLK to 10% of SMBDATA
10% or 90% of SMBDATA to 10% of SMBCLK
(Note 4)
Between start/stop conditions
Master clocking-in data
_______________________________________________________________________________________
3
Fan Controller and Remote Temperature Sensor
with SMBus Serial Interface
MAX1669
ELECTRICAL CHARACTERISTICS
(V
CC
= +3.3V,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 5)
PARAMETER
ADC AND POWER SUPPLY
Temperature Resolution (Note 1)
Temperature Error, Remote Diode (Note 2)
Supply Voltage Range
Average Operating Supply Current
Conversion Time
Conversion Rate
FAN OUTPUT
FAN Output Source Current
FAN Output Sink Current
FAN PWM Frequency Error
FAN Total Unadjusted Error
FAN Output Voltage High
FAN Output Voltage Low
SMBus INTERFACE
Logic Input High Voltage
Logic Input Low Voltage
SMBDATA,
ALERT, OVERT,
I/O1, I/O2
Output Low Sink Current
ALERT, OVERT,
I/O1, I/O2 Output
High Leakage Current
Logic Input Current
ADD_, I/O1, I/O2, SYNC, SMBCLK, SMBDATA;
V
CC
= 3V to 5.5V
ADD_, I/O1, I/O2, SYNC, SMBCLK, SMBDATA;
V
CC
= 3V to 5.5V
Pin forced to 0.4V
Pin forced to 5.5V
Logic inputs forced to V
CC
or GND
-1
6
1
1
2.1
0.8
V
V
mA
µA
µA
PWM mode, V
FAN
forced to 2.9V
PWM mode, V
FAN
forced to 0.4V
PWM mode, any setting
DAC mode, any setting, R
L
= 10kΩ to GND
DAC mode, FAN duty factor = 1111b,
I
OUT
= 5mA
DAC mode, FAN duty factor = 0000b,
I
OUT
= -5mA
-25
-5
2.94
0.2
10
-10
+25
5
mA
mA
%
%FS
V
V
Autoconvert mode, average measured over
1sec, FAN output set to 150Hz mode
From stop bit to conversion complete
Autoconvert mode
47
1.6
2.4
Monotonicity guaranteed
T
R
= -55°C to +125°C, diode ideality factor = 1.013
8
-5
3
5
5.5
100
Bits
°C
V
µA
ms
Hz
CONDITIONS
MIN
MAX
UNITS
Note 1:
Guaranteed but not 100% tested.
Note 2:
T
R
is the junction temperature of the remote diode. The temperature error specification is optimized to and guaranteed for a
diode-connected 2N3906 transistor with ideality factor = 1.013. Variations in the ideality factor “m” of the actual transistor
used will increase the temperature error by *. See the Temperature Error vs. Remote Diode Temperature graph in the
Typical Operating Characteristics
for typical temperature errors using several random 2N3906s. See
Remote Diode
Selection
for remote diode forward-voltage requirements.
Note 3:
The SMBus logic block is a static design that works with clock frequencies down to DC. While slow operation is possible, it
violates the 10kHz minimum clock frequency and SMBus specifications, and may monopolize the bus.
Note 4:
Note that a transition must internally provide at least a hold time in order to bridge the undefined region (300ns max) of
SMBCLK’s falling edge.
Note 5:
Specifications to -40°C are guaranteed by design and not production tested.
1.013
*
∆T =
−
1
273.15k
+
T
R
m
(
) (
°
C
)
4
_______________________________________________________________________________________
Fan Controller and Remote Temperature Sensor
with SMBus Serial Interface
Typical Operating Characteristics
(Temperature error = measured - actual, T
A
= +25°C, unless otherwise noted.)
MAX1669
TEMPERATURE ERROR
vs. LEAKAGE RESISTANCE
MAX1669-01
TEMPERATURE ERROR
vs. REMOTE DIODE TEMPERATURE
MAX1669-02
TEMPERATURE ERROR vs.
POWER-SUPPLY NOISE FREQUENCY
16
TEMPERATURE ERROR (°C)
14
12
10
8
6
4
2
0
-2
V
IN
= 100mVp-p
V
IN
= 250mVp-p
V
IN
= SQUARE WAVE APPLIED TO
V
CC
WITH NO 0.1µF V
CC
CAPACITOR
MAX1669-03
40
30
TEMPERATURE ERROR (°C)
20
PATH = DXP TO GND; CONFIG = 02h
10
0
-10
-20
PATH = DXP TO V
CC
(5V); CONFIG = 02h
-30
-40
1
10
LEAKAGE RESISTANCE (MΩ)
2.0
1.5
TEMPERATURE ERROR (°C)
1.0
0.5
0
-0.5
-1.0
-1.5
-2.0
RANDOM 2N3906s FROM
DIFFERENT MANUFACTURERS
18
100
-60 -40 -20 0
20 40 60 80 100 120 140
1K
10K
100K
1M
10M
100M
TEMPERATURE (°C)
PSNF (Hz)
TEMPERATURE ERROR vs.
COMMON-MODE NOISE FREQUENCY
MAX1669-04
TEMPERATURE ERROR
vs. DXP - DXN CAPACITANCE
0
TEMPERATURE ERROR (°C)
-2
-4
-6
-8
-10
-12
-14
-16
V
CC
= 5V
MAX1669-05
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX1669-06
8
7
TEMPERATURE ERROR (°C)
6
5
4
3
2
1
0
-1
-2
1M
10M
100M
C = 27nF
C = 2200pF
V
IN
= 50mVp-p AC-COUPLED TO DXN
C = DXN - DXP CAPACITANCE
2
7
STANDBY SUPPLY CURRENT (µA)
6
5
4
3
2
1
0
1G
0
10
20
30
40
50
3.0
3.5
4.0
4.5
5.0
5.5
FREQUENCY (Hz)
DXP-DXN CAPACITANCE (nF)
SUPPLY VOLTAGE (V)
RESPONSE TO THERMAL SHOCK
MAX1669-07
PWM FREQUENCY vs. CODE (F3F2F1F0)
160
140
PWM FREQUENCY (Hz)
120
100
80
60
40
V
CC
= +3.3V
V
CC
= +5V
MAX1669-08
120
100
TEMPERATURE (°C)
80
60
40
20
0
-2
0
2
4
TIME (sec)
6
8
180
CMPT3906 IMMERSED IN
+115°C FLUORINERT BATH
10
20
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
CODE (F3F2F1F0)
_______________________________________________________________________________________
5
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