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UCC21750-Q1: Possible to shutdown APWM output?

Chuqiang Wen
Expert 5865 points
Part Number: UCC21750-Q1


Tool/software:

Hi team, 

Right now, customer connect APWM to MCU and AIN short to COM. APWM will continue to output highest duty cycle PWM signal to MCU. At this configuration, APWM signal will couple to near circuit and affect the operation. So I would like to check with you if any way can shutdown APWM output except disable VCC or VDD and HW connection? Or any way to decrease the duty cycle without HW connection? 

Thanks!

Ethan Wen

  • 0
    TI__Expert 8335 points

    Hi Ethan,

    APWM duty cycle is fixed 400Khz. When AIN =0V, it has highest duty cycle of ~95% and when AIN=5V, then it has lowest duty cycle of ~6%.

    If you want to reduce the duty cycle, please connect 5V (HV side wrt to COM) to AIN.

    Another option is connect RC filter on the APWM pin so that the APWM DC will be converted into DC voltage which can be connected to the ucontroller. Hope it helps.

    Thanks

    Sasi

  • 0 in reply to Sasikala Thangam
    TI__Expert 5865 points

    Hi Sasi, 

    Just sent questions from email. Please help check! 

    Thanks!

    Ethan Wen

  • 0 in reply to Chuqiang Wen
    TI__Expert 8335 points

    Hi Ethan,

    I am reaching out to Design to see if there is any test mode option to stop APWM. But i think that its not feasible to stop it completely. However if we understand the problem deeper, can suggest other alternate options. Let us continue this discussions in email. Let me close the E2E.