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 transistor—typically a low-cost, easily mounted 2N3906 PNP type—replacing conventional thermistors or thermocouples. Remote accuracy is ±3°C for transistors from multiple manufacturers, with no calibration needed. The MAX1669 has an independent fan controller with a low current logic output requiring external power components 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.

Features
♦ Measures Remote CPU Temperature
♦ No Calibration Required
♦ 20Hz to 160Hz PWM Output for Fan
♦ PWM Frequency Sync Input (260kHz)
♦ Flexible Fan Interface: Linear or PWM
♦ SMBus 2-Wire Serial Interface
♦ Programmable Under/Overtemperature Alarms
♦ ALERT Latched Interrupt Output
♦ OVERT Thermostat Output
♦ Two GPIO Pins
♦ Write-Once Configuration Protection
♦ Supports SMBus Alert Response
♦ ±3°C Temperature Accuracy (-40°C to +125°C, remote)
♦ 3µA Standby Supply Current
♦ +3V to +5.5V Supply Range
♦ Small 16-Pin QSOP Package

Applications
    Pentium® CPU Cooling
    Desktop Computers
    Notebook Computers
    Servers
    Workstations