TPS54325: Short Circuit Behavior at Startup

Allan Fan

Part Number: TPS54325

Hi Expert,

The over current event after normal start up may cause UVP. The trigger time to turn off both high/low side fets from datasheet is 1.7x Tss + 250us.

My question is when customer did short circuit test at initial startup, the trip time was longer than 1.7Tss + 250us but Vo had been lower uvp already. What would be expected trip time for this short circuit power up condition?

Thanks.

Allan

over 3 years ago

0 JohnTucker over 3 years ago

TI__Guru**** 191445 points

Allan,

My simulations are showing a slightly faster trip time. Can you post a start up waveform with Vss, Vsw an Vout?

0 Kao Mick over 3 years ago in reply to JohnTucker

Intellectual 330 points

HI SIR

Vin:12V Vout:3.3V

L:4.7uH Cout:22uF

Cin:22uF

SoftStart Cap:6800pF about 6.8*0.765/2 = 2.6ms

We did short circuit test at initial startup.

ch1: Vout

ch2: Iout

Iout 4A lasts about 4.6ms.

What is the definition of this time?