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LM5176: Specific information on the output drivers operation

Dominik Bejma
Prodigy 20 points
Part Number: LM5176

Hello. I need some additional information on the output drivers of LM5176 that are not specified in datasheet: 

1. What current is being drawed by pins BOOT1/BOOT2 while pins HDRV1/HDRV2 are in high state for long time? 

2. How pins LDRV1/LDRV2?HDRV1/HDRV2 act when device is in shutdown mode (when ENABLE pin is lower than VEN(STBY))? More specifficly will they be shut to PGND/SW1/SW2 respectively or will they be open? How would they react when device is shutdown but some voltage would occur on them? 

Best regards Dominik Bejma

  • 0
    TI__Guru 58641 points

    Hi Dominik,

    Thank you for using the E2E forum.

    BOOT1 and BOOT2 are the supply for the high side driver. In static mode this just have to deliver the leakage current for the driver stage and the external MOSFETs.
    So there is just a small current compared to the switching state.

    2. The pins are put to low state, so LOx to GND and HOx to SWx.

    I am not sure if this is done with the full driver strength or if this gets limited. I need to check with design and let you know till end of next week.

    Best regards,

     Stefan

  • 0 in reply to Stefan Schauer
    Prodigy 20 points

    Thank you for Your answer! 

    1. From what I understood the die resets the bootstrap if due to the leakage current the voltage on BOOT1/BOOT2 drops bellow UVLO level, by switching SW1/SW2 node to ground, right?

    2. That will be enough, thank you! 

    Best regards Dominik Bejma

  • +1 in reply to Dominik Bejma
    TI__Guru 58641 points

    Hi Dominik,

    yes, you are right the Boot caps will be precharged in that idle time.

    Best regards,

     Stefan