The MAX6678 monitors its own temperature and the temperatures of two external diode-connected transistors, which typically reside on the die of a CPU or other integrated circuit. The device reports temperature values in digital form using a 2-wire serial interface. The MAX6678 provides a programmable alarm output to generate interrupts, throttle signals, or overtemperature shutdown signals. The 2-wire serial interface accepts standard System Management Bus (SMBus)™ write byte, read byte, send byte, and receive byte commands to read the temperature data and program the alarm thresholds. The temperature data controls a PWM output signal to adjust the speed of a cooling fan, thereby minimizing noise when the system is running cool, but providing maximum cooling when power dissipation increases. Five GPIO pins provide additional flexibility. The GPIO power-up states are set by connecting the GPIO preset inputs to ground or VCC. The MAX6678 is available in a 20-pin QSOP package and a 5mm x 5mm thin QFN package. It operates from 3.0V to 5.5V and consumes just 500µA of supply current.
The MAX6678 monitors its own temperature and two external diode‑connected transistors, typically on a CPU or other IC. It reports temperature digitally via a 2‑wire SMBus interface and provides programmable alarm outputs for interrupt, throttle, or over‑temperature shutdown signals.
The device includes two PWM outputs for fan speed control, five configurable GPIO pins, and operates from 3.0 V to 5.5 V while consuming only 500 µA. It is offered in a 20‑pin QSOP package and a 5 mm × 5 mm thin QFN package, supporting up to four devices on the same SMBus bus.
| Operating supply voltage range | 3.0 V – 5.5 V |
|---|---|
| Supply current (typical) | 0.5 mA |
| Operating temperature range | -40 °C – +125 °C |
| Temperature resolution | 1 °C (8‑bit) |
| Number of GPIO pins | 5 |
| PWM outputs for fan drive | 2 |
| Package options | 20‑pin QSOP, 5 mm × 5 mm thin QFN |
| SMBus slave addresses | 4 |
It operates from 3.0 V to 5.5 V.
The device monitors its own temperature and two external diode‑connected transistors, giving two temperature channels.
Fan speed is controlled via two PWM outputs that can drive MOSFETs, be converted to a DC voltage, or directly drive a fan’s PWM input.