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TPS92520-Q1: TPS92520 internal PWM dimming question

qinlei
Intellectual 330 points
Part Number: TPS92520-Q1

Hello 

The PWM frequency set internally in TPS92520 is abnormal. We use the combination of TPS92682 + TPS92520, with 2-phase boost and 6-phase buck. There is no problem using the default PWM frequency. When using 215Hz and the duty cycle is 20%, the actual test frequency is 113Hz and the duty cycle is 8%.  could you give me an explation for this ? 

The parameter settings are as follows: 

TPS92682 boost 50.8v

switching frequency: 178kHz

TPS92520 switching frequency: 437kHz

thank you 

best regards 

  • 0
    TI__Mastermind 18955 points

    Hello Qinlei,

    Are you using our EVM or is this on your own board?  Can you share with me waveforms showing me this 113 Hz?  Also, I would like to see a read of all the registers when this happens.  113Hz is very close to PWMDIV[2:0] = 111 (fpwm=108Hz).  Are you sure didn't program it incorrectly?  You need to verify SPI transactions.  Please provide me with adequate information to make an assessment?  You need to provide waveforms of I_L preferably , SW node, Vout.  I need SPI writes and reads.  I also need schematics if they are different then the EVM.  Lets start with this and then maybe we can figure out what is going on.

    -fhoude 

  • 0 in reply to fhoude
    TI__Mastermind 18955 points

    I am assuming you resolved your issue and I am closing the E2E posts.  Reopen it if that isn't the case.