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TPS55287: Time for recovery from the Shutdown Mode

Pavel Tatar
Prodigy 20 points
Part Number: TPS55287

Tool/software:

Hi,

is defined time required to recovery from the Shutdown Mode?
 1. for the I2C communication
 2. for the start of switching (when the Soft Start time beginning)

This parameter isn't present in the datasheet.

Condition in my design:
  * Vin 4V (3.5-4.2) still present during the Shutdown Mode
  * En/UVLO the logic signal provided from the MCU GPIO powered from 3V

When I put the En/UVLO to logic 1 (rise time < 1µs), I can't get the ACK on the I2C bus. I tried insert 2ms wait to code with same result. When I stopped the code (with debuger) for a few second, TPS55287 works normally after resuming the code.

Regards,

Pavel

  • +1
    TI__Genius 15180 points

    Hi Pavel,

    This depends on how fast VCC voltage is set up. Can you provide waveforms of EN, VCC SCL SDA waveforms? 

    Regards,

    Mulin

  • 0 in reply to Mulin Yuan
    Prodigy 20 points

    Hi Mulin,

    thank you.

    Ok, we modify the FW, assert of Enable will be in other section of code and first I2C attempt will be delayed > 10ms. When It's Ok problem probably solved.

    Waveforms attached (It's only from the sample code).  Capacitor on VCC is 10µ (datasheet "A ceramic capacitor of more than 4.7 μF is required...", however we haven't other 4µ7 in BOM instead of many 10µ).

    Regards,

    Pavel



    TPS55287 waveforms allTPS55287 waveforms Vcc detail  

  • 0 in reply to Pavel Tatar
    TI__Genius 15180 points

    Hi Pavel,

    This result makes sense. Customer is using large capacitance for VCC cap so it takes long time to charge it. I will close this thread now. If you see more questions, feel free to reply.

    Regards,

    Mulin

  • 0 in reply to Mulin Yuan
    Prodigy 20 points

    Hi Mulin,

    thank you. I haven't any questinou about it. You can close this thread now.

    FYI we tests more boards and some different capacitors in future, however we don't expect totally different results and new question.

    Regards,

    Pavel