SLAAEU3 June   2025 MSPM0C1104

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Four Wire Cooling Fans
  5. 2Cooling FAN Controller with MSPM0 Designs
    1. 2.1 Design with MSPM0C1104 and MSPM0C1106
    2. 2.2 Design with MSPM0H3215 and MSPM0H3216
  6. 3Software Introduction
    1. 3.1 Software Working Flow
    2. 3.2 Function Description
      1. 3.2.1 PWM Output
      2. 3.2.2 TACH Capture
      3. 3.2.3 ADC Sample
      4. 3.2.4 FAN Fault Detection and Overflow Maximum Value
    3. 3.3 I2C Communication Protocol
    4. 3.4 Registers Definition in the Demo
  7. 4Demo Test with Hardware
    1. 4.1 Hardware Setup
    2. 4.2 Software Setup
    3. 4.3 Running Demo Code
  8. 5Summary
  9. 6References

1 Four Wire Cooling Fans

Four wire cooling fans have better performance and higher reliability than three wire or two wire cooling fans. Four wire cooling fans are popular in the cooling system in the server or PC. The four wire cooling fan signals are listed in Table 1-1.

Table 1-1 4-Wire Cooling Fan Signals
Wire Color Signal Details
Black GND
Red VCC Power supply to the FAN, normally 12V
Yellow TACH Speed signal, normally open drain output
Blue PWM Speed control; pulled up to 5V in the fan module or open drain input

Change the PWM duty cycle to control the speed of the fan. The TACH signal is used to determine the actual speed of the fan. Use a Hall sensor in the fan module to generate one or more pulses to turn a circle. The number of pulses depends on the pole-pare numbers of the motor.