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