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TPS543B20: Protection behavior questions

Oliver Lin
Expert 3365 points
Part Number: TPS543B20

Hi expert,

From datasheet 8.4.14,

1. We would like to check that OVP the hiccup restart, does that mean the device keeps restarts until the restart successfully? Otherwise, device will keep trying.

2. About the UVP, does that mean once triggering UVP and run through hiccup time-out(7xTss), and restart again?

3. What's the differrence of OVP and UVP behavior? Both OVP and UVP apply hiccup time-out?

Thank you,

Oliver

  • 0
    TI__Expert 5446 points

    Hi Oliver,

    1. When the device enters hiccup mode, the device will timeout for the duration of 7 soft-start cycles before attempting a normal start-up. If the fault has not yet cleared, then the hiccup process will repeat.

    2. Yes, the same goes for UVP.

    3. Both follow the same process for hiccup time-out. The only difference between the UVP and OVP behavior is the shutdown method. For UVP, both fets are turned OFF so that switching is terminated. For OVP, the high-side fet is turned OFF and the low side fet is turned ON so that SW is tied directly to GND.

    Best regards,

    Britton

  • 0 in reply to Britton Jones
    TI__Expert 3365 points

    Hi Britton,

    Thank you for your explanation, do we have any graph to show the sequence, this is kind of hard for us to have the full picture from the words? Appreciate your help here

    Thanks,

    Oliver

  • 0 in reply to Oliver Lin
    TI__Expert 5446 points

    Hi Oliver,

    Here is a scope shot of UVP behavior. The pink waveform is VOUT and the yellow waveform is SW. In this case, both FETs are turned off, switching terminates, and you can see the "slow" dissipation of charge as VOUT reduces to 0V.

    Contrary to this, here is a scope shot of OVP behavior. The red waveform is VOUT, the yellow waveform is SW, the blue waveform is PGOOD and the green waveform is RSP. In this case, the high-side FET is turned OFF and the low-side FET is turned ON to short VOUT directly to GND. You can see the "fast" dissipation of VOUT to 0V, almost instantaneously. These 2 images are not taken with the same time scale, but you can get an idea for how quick this event happens by looking at SW.

    Best regards,

    Britton