TPS54340: TPS54340 input current spike double than stable current .

Hello

It is possible that you are experiencing the normal in-rush current of the device.

The soft-start time may be too fast.

Can you give us a picture of the input current and/or the inductor current during start-up.

Are you starting up from the EN input ?

What is your input voltage and load during start-up ?

Thanks

hello,

1 .please find attached image of  input current during start up .

2. EN pin left open .

3. input voltage is +27V ,load during start up is +11V/650mA .

Hello

I think you are seeing the normal inrush current during start-up.

If you can put a short wire loop in series with the inductor and use your

current probe to look at the inductor current and also look at the voltage on the SW 

pin and the output, we can see better if it looks like a normal start-up.

Thanks

Hi Sir,

Yes i also think it is Normal  inrush current during start-up . My issue is i have to use fixed +27V/0.35A smps to drive this device which are taking +27V/300mA in normal mode which is not satisfied because of this initial start current . and my  fixed +27V/0.35A smps voltage drop to +7V .