MAX6640

19-3344; Rev 2; 10/08 KIT ATION EVALU LE B A IL A AV www.DataSheet4U.com 2-Channel Temperature Monitor with Dual Automatic PWM Fan-Speed Controller General Description The MAX6640 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 dual PWM 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 MAX6640 is available in 16-pin QSOP and 16-pin TQFN 5mm x 5mm packages. It operates from 3.0V to 3.6V and consumes just 500µA of supply current. Features o Two Thermal-Diode Inputs o Local Temperature Sensor o 1°C Remote Temperature Accuracy (+60°C to +100°C) o Two PWM Outputs for Fan Drive (Open Drain; can be Pul...