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TPS92520-Q1: LHM behavior

shaher Elhalaby
Intellectual 260 points
Part Number: TPS92520-Q1

Tool/software:

Hello,

we wonder what if we set bits LH1INTPWM and LH1100D in LHCFG1 inside the chip, what should be the expected behavior ?

also we have a challenge that you give support in it 

we configured the LHCFG1 with value 0x3B ,LHPWNL -> 0xFF LHPWMH-> 0x01 and we did the following we expected to get 100% duty however the obtained was lower duty 

1. we set UDMI1 with 80%/50% 

2. send the chip to enter LHM

 

expected the Duty of channel 1 to be 100% however the obtained was 80%/50% in raw .

so could you support why we faced that ?

Best Regards,

shaher

  • 0
    TI__Mastermind 23196 points

    Hello Shaher,

    If you set LHCFG1 to 0x3B, then the PWM is set to what ever is set in LH1PWML and LH1PWMH, and you set CH1PWML to 0xFF and CH1PWMH to 01 which give ~50%.    LL1100D is set to 0 so that makes CH1t refer to internal pwm given this settings.  If you want it to be 100% duty cycle then that bit needs to be set to 1.  I am confused, it is doing what you programmed it to do.  Please recheck what you programmed too.  

  • 0 in reply to fhoude
    Intellectual 260 points

    Hello Fhoude,

    Sorry the value of LHCFG is 0x3F not 0x3B ,and also the PWM is not constant if I applied 80% in pin UDMI it will be 80% in Buck output will won't case to Bit 5/2 in the LHCFG or the value specified in registers LH1PWML and LH1PWMH

    Best Regards,

    shaher

  • 0 in reply to shaher Elhalaby
    TI__Mastermind 23196 points

    UDIM is gates the output being turned on.  If UDIM goes low then the output is shut off no matter what the LHCFG is set to.  If you plan to use internal settings then UDIM has to always be high.