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UCC28250: UCC28250 Disable voltage on EN_pin

Zhanpeng Li
Intellectual 2130 points
Part Number: UCC28250

Hi team,

it seems that we met a bug on using our EN_pin to enable and disable the device:

  • it would work well if we put over 2.25V on EN_pin to enable the device;
  • but if we put 2.2v on En_pin, it seems that the device would work in an abnormal working model. the output OUTA frequency would change to 41k somehow and could not be control by RT_pin.

so, we have a question on EN_pin, how much voltage level should we put here to fullly disable the device? do we actually have another working model if our volatge on EN_pin only have small gap with 2.25V?

BR

Brandon 

  • 0
    TI__Mastermind 24915 points

    Hi Brandon,

    It seems you are presenting a voltage at the EN pin which is very close to the 2.25V threshold. In the application this is undesirable and we want to pass through the threshold as quickly as possible. Still, while this could cause chatter (PWM ON/OFF/ON/OFF/etc) around the EN threshold, I see no reason for the frequency shift you are describing. When the frequency shifts to 47 kHz from whatever it was designed to be, does it stay locked at this frequency? Can varying input voltage or load current cause it to change? Can you share a schematic and waveforms showing what you are measuring in the lab?

    Regards,

    Steve M