MAX1669 Datasheet, PDF (1/20 Pages) Maxim Integrated Products – Fan Controller and Remote Temperature Sensor with SMBus Serial Interface

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.
Pentium^® CPU Cooling
Desktop Computers
Notebook Computers
Servers
Workstations
Applications
Typical Operating Circuit appears at end of data sheet.
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
PART
MAX1669EEE
Ordering Information
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
16 QSOP
Pin Configuration
TOP VIEW
I/O1 1
I/O2 2
ADD0 3
ADD1 4
ADD2 5
AGND 6
DXN 7
DXP 8
MAX1669
16 OVERT
15 ALERT
14 SMBDATA
13 SMBCLK
12 PGND
11 FAN
10 SYNC
9 V_CC
Pentium is a registered trademark of Intel Corp.
QSOP
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