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LM96163: Tach Count for 0 RPM

Roy Hsu
Genius 9190 points
Part Number: LM96163

Hi Team,

What would be the tach count for 0 RPM (fan is not spinning at all) of this device? With the equation below, only f=0 makes FAN_RPM 0. 

Even if tach count is at full scale, it translates into ~82 RPM using the equation above.

Thanks!

Roy

  • 0
    TI__Mastermind 27645 points

    Hi Roy,

    The TACH Count registers count the number of periods of the tachometer clock between pulses on the tach input.

    When the Fan is at 0RPM, you would therefore expect a maximum reading of 0xFFFF. As you've noted, 0RPM is outside the FAN_RPM range that the LM96163 could count, as it would see no edges on the TACH line. 

    Best Regards,
    Brandon Fisher