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TPS54824: PGOOD thresholds

Cosmin P
Intellectual 1690 points
Part Number: TPS54824
Other Parts Discussed in Thread: TPS54424

Hello,

Datasheet specifies the PGOOD thresholds as typical values.
Can you please specify the min/max values as well?

This is significant for extreme load transient events: as example, if the load is switched form Iomax to 0A and output overshoots, the PGOOD may toggle and reset the system if used for sequencing.

The worst lowest OVP PGOOD threshold after start-up will be then used to size the design for the right amount of Cout and loop BW.
Similar for the highest UVP PGOOD threshold when the load kicks in.

Thank you

  • 0
    TI__Mastermind 35215 points

    Hi Cosmin,

    In the TPS54824 we added in a deglitch time for PGOOD to help prevent a load step from causing PGOOD to go low. The FB voltage needs to be past the thresholds for 16 clock cycles for PGOOD to transition low. With 500 kHz fsw the FB voltage needs to be past the threshold for 32 µs for PGOOD to transition low. This deglitch time does not apply to OVP so OVP will still trip immediately.

    Below are the min,max for PGOOD to transition low based on the data I have. This min,max could also be used for the TPS54424.

    VFB rising fault: 105%, 113% (The average for the set of data I am looking at is 109%)

    VFB falling fault: 85%, 93%

    Best Regards,
    Anthony