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 (SMBusTM) 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.
The MAX6640 monitors its own temperature and up to two external diode‑connected transistors, typically found on CPUs, FPGAs or GPUs. It communicates via a standard SMBus 2‑wire interface, allowing temperature reads, alarm threshold programming, and fan‑speed control.
The device includes two open‑drain PWM fan outputs, tachometer inputs, and status outputs (OT, THERM, ALERT, FANFAIL). It operates from 3.0 V to 3.6 V, consumes low standby current, and can measure temperatures up to +150 °C with ±4 % fan‑speed accuracy.
| Operating Supply Voltage Range | 3.0 V to 3.6 V |
|---|---|
| Fan‑Speed Measurement Accuracy | ±4 % |
| Maximum Measurable Temperature | +150 °C |
| Number of PWM Fan Outputs | 2 (open‑drain, up to 13.5 V pull‑up) |
It uses a standard SMBus 2‑wire/I²C‑compatible serial interface.
The MAX6640 provides two open‑drain PWM fan outputs that can be pulled up to 13.5 V.
The device operates from 3.0 V to 3.6 V.
It can measure temperatures up to +150 °C.