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TPS54821 VIN and PVIN supply input query for 4V/8A output

Manoj Agarwal
Expert 1030 points
Other Parts Discussed in Thread: TPS54821

We are using TPS54821 for generating 4V/8A. We are providing input voltage of 4V to 5.5V at PVIN and 9V(fixed) at VIN. We want to would like to know

1. Max current requirement for VIN pi for abaove said configuration.

2. Will TPS54821 would be able to generate 4V / 8A output when input voltage drop to 4.4V.

  • 0
    TI__Guru**** 191445 points
    I do not support TPS54821 directly, but I can give you a general idea.

    1. Vin non-switching current is 600 uA typ and 800 uA max. During operation, VIN also sullies the BOOT charge circuit and the low side gate driver. I do not have any actual measured data for it, but it is probably in the range of 10 mA average. Maybe someone from that team can measure it.

    2. The drop across the FETs is about 320 mV. TPS54821 can operate at 100 % duty cycle until the BOOT charge runs out. 400 mV of input headroom should be enough to ensure constant 4 V regulation.