MAX6639

www.DataSheet4U.com 19-3682; Rev 0; 5/05 2-Channel Temperature Monitor with Dual, Automatic, PWM Fan-Speed Controller General Description The MAX6639 monitors its own temperature and one external diode-connected transistor or the temperatures of two external diode-connected transistors, typically available in CPUs, FPGAs, or GPUs. The 2-wire serial interface accepts standard System Management Bus (SMBus TM ) write byte, read byte, send byte, and receive byte commands to read the temperature data and program the alarm thresholds. Temperature data can be read at any time over the SMBus, and three programmable alarm outputs can be used to generate interrupts, throttle signals, or overtemperature shutdown signals. The temperature data is also used by the internal dualPWM fan-speed controller to adjust the speed of up to two cooling fans, thereby minimizing noise when the system is running cool, but providing maximum cooling when power dissipation increases. Speed control is accomplished by tachometer feedback from the fan, so that the speed of the fan is controlled, not just the PWM duty cycle. Accuracy of speed measurement is ±4%. The MAX6639 is available in 16-pin QSOP and 16-pin TQFN 5mm x 5mm packages. It operates from 3.0V to 5.5V and consumes just 500µA of supply current. Features ♦ 2 Thermal-Diode Inputs ♦ Up to 25kHz PWM Output Frequency ♦ 3 Selectable SMBus Addresses ♦ Local Temperature Sensor ♦ 1°C Remote Temperature Accuracy ♦ Two PWM Outputs for Fan Drive (Open Dra...