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LM63: PWM setting question

Tommy Tzeng
Genius 4805 points
Part Number: LM63

Hi Team,

we currently have a project, use LM63 to control Fan speed.

but when setting the PWM frequency, it is found that if the 4D value is set to 0x07, the duty cycle 4C value( 0~14) is set to 0x14~0x10 will be 100%, and it will not become 64.2% until it is set to 0x09.

we use i2c (100kHz) to write the value, and the read value is also correct, but PWM signal output have a problem. could you help confirm or any suggestion for us.

    i2cset -f -y 0 0x4c 0x4D 0x07
    i2cset -f -y 0 0x4c 0x4c  0x10 "

  • 0
    Intellectual 520 points

    Hi Tommy,

           i2cset -f -y 0 0x4c 0x4D 0x07
            i2cset -f -y 0 0x4c 0x4c  0x0B ==> PWM is %75

       

            i2cset -f -y 0 0x4c 0x4D 0x07
            i2cset -f -y 0 0x4c 0x4c  0x07 ==> PWM is %50

           Therefore,  

            i2cset -f -y 0 0x4c 0x4D 0x07
            i2cset -f -y 0 0x4c 0x4c  0x09==> PWM is %64 

            is correct

  • 0 in reply to Sean Yu28
    TI__Expert 6820 points

    Hi Tommy,

    To clarify is the issue that before writing to the 0x4C register that the Duty cycle is at 100%?  The device default is to Spin-up at 100% RPM.  Please see register 0x4B for spin-up settings.   This is probably what you are seeing on the device's PWM.  

    Thanks,

    David