TPS55340: TPS55340 disabled

Hi Andrea,

Can you show me the schematic and layout? 

Please make sure the power supply current limit is big enough.

Thank you for your prompt replay.

This is the original schematic

Hi Andrea,

The schematic looks good. I didn't see anything wrong.

Can you also share the layout please? 

One more thing, when you did the test, did you find this behavior on several boards or only one? Have you checked the IC is soldered well exactely?

2 boards same problem.

I have 5.2V from other voltage regualtor TPS61232

Hi Andrea,

The layout is not good.

The voltage regulators including Buck converter, Boost converter layout is different from signal chain IC layout because it needs to provide huge current. For a 1OZ copper PCB, the trace can only go through 1A with 10 mil width. For a high frequency DCDC converter, layout is more important besides the width. 2 layers PCB is recommended and the bottom layer would be all GND. Please refer to TPS55340 datasheet page 27 layout recommendations for more detailed description. 

Below is a simple example:

Hi Zack

You are right

Thank you

Because i didn't  need a professional pcb i didn't check the track/current......

But it's strange..form this error gets this problem..

Hi Andrea,

You need a second version PCB.

If you want to debug this version PCB, you need to share the startup Vin, Vout, SW waveform.

I'd like use this pcb only for some measurement..so..i'd want continue with this.

Now it's difficult, sometimes after i put a load (0.5W) works..but if i take off the load..it returns to diabled mode.

It's very strange

This this when i power on and it dosen't work (SW)

Here when it's workings i put and take off the load

Vout

Hi,

You said with a 0.5W load, it works. Is the Vout 24V and very stable?

What happened on the third waveform that Vout decrease from 24V?

Sometimes after i take off the load Vout decrease 

or the components is disabled

Hi Andrea,

It's hard to say the root cause because too many unknown big parasitic resistance and parasitic inductance caused by the PCB. If you want to continue testing the other circuits on the board, you can use a external 24V power supply to supply rest circuits. 

You can share the layout next time for review on E2E.

Ok I'll try with this new pcb