2-Channel Temperature Monitor with Dual Automatic PWM Fan-Speed Controller and Five GPIOs

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.

Applications

* Desktop Computers * Networking Equipment * Notebook Computers * Servers * Workstations

* Two Thermal-Diode Inputs

* Local Temperature Sensor

* Five GPIO Input/Outputs

* Two PWM Outputs for Fan Drive (Open Drain; May Be Pulled Up to +5V)

* Programmable Fan-Control Characteristics

* Automatic Fan Spin-Up Ensures Fan Start

* Controlled Rate of Change Ensures Unobtrusive Fan-Speed Adjustments

* 1°C Remote Temperature Accuracy (+60°C to +145°C)

* Temperature Monitoring Begins at POR for Fail-Safe System Protection

* Active-Low OT Output for Throttling or Shutdown

* Four Versions Available, Each with a Different Address

* 5mm x 5mm TQFN Package