TPS54360B-Q1: power TPS54360b-Q1 fault

andrea penna

Part Number: TPS54360B-Q1
Other Parts Discussed in Thread: TPS54360

i have a power problem on a prototype board.
If the power supply reaches up to 30V input, both the 15V and the + 5v are regular.
If the power exceeds 40V up to 48V, I have two chip breaks.
I think it is the ENABLE, but in one case it is floating and in the other it is through two resistors. What is the problem? How to fix it?
The 15V are activated immediately, while the 5V is activated on command.
I attach the pdf of the diagram of the two power supplies

Andrea Penna

over 4 years ago

0 Frank De Stasi over 4 years ago

TI__Guru 73115 points

Hello

It sound like an overvoltage on the input.

Please use a scope to monitor the input voltage on the regulators for any overvoltage due to ringing.

You have some kind of filter choke on the input; this could be causing ringing.

You should try using an Al. input cap of about 47uF or 100uF as an experiment to damp any overvoltage ringing.

A clamp diode or TVS at the input to the regulators, rather than farther away may also be needed.

Also, please send us a view of your PCB layout.

Thanks

0 andrea penna over 4 years ago in reply to Frank De Stasi

Prodigy 150 points

MOTHER_BOARD_2FIRE.zip

pcb in attach

the 100uF are to put before the LC filter or after?
From the diagram I removed the 2 1000uF at the input.
Is the smbj48ca okay before the regulator?

0 Frank De Stasi over 4 years ago in reply to andrea penna

TI__Guru 73115 points

Hello

The 100uF should be near the regulator.

I think that the snubber you may be OK.

However, the maximum clamp voltage is around 70V. That may be a little too high.

We will look at your layout and get back to you as soon as possible.

Thanks

0 Frank De Stasi over 4 years ago in reply to Frank De Stasi

TI__Guru 73115 points

Hello

Please send plots of the relevant PCB layers.

We can not view the gerbers.

Thanks

0 andrea penna over 4 years ago in reply to Frank De Stasi

Prodigy 150 points

THE BOARD IS 4 LAYER

TOP GREEN

BOTTOM RED

INNER 2 GND

INNER 1 POWER

I INSERT PITCURE POWER ZONE WITH TWO TPS54360 OF SCHEMATIC.

0 andrea penna over 4 years ago in reply to andrea penna

Prodigy 150 points

I made the changes you advised me.
Removed LC filter, TVS smbj36ca instead of smbj48ca and inserted a 100uF 60V at the input of the TPS.
Now at 48 volts both regulators work.
A question:
to enable the 5V regulator, I get 48 to the enable with a divider. All right? or is it better to bring the 15V to enable?

Thank you

Andrea Penna

0 Frank De Stasi over 4 years ago in reply to andrea penna

TI__Guru 73115 points

Hello

I am glad it is working.

Your enable divider looks like it will divide the 48V down to about 8V or so.

This is very close to the maximum allowed for the EN input. I would try to lower

that voltage a little.

On your PCB the traces going to the power components are a little narrow. It would be best

to make them wider. Also, the capacitors C143 and C155 could be closer to the VIN and GND pins of the regulators.

Thanks

0 Frank De Stasi over 4 years ago in reply to Frank De Stasi

TI__Guru 73115 points

Hello

I will close this post.

If you have further questions, you can re-open at any time.

Thanks

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TPS54360B-Q1: power TPS54360b-Q1 fault