TPS54540: Issue with TPS54540 to support a load current of 1 amp.

Deepika Manjunath60

Part Number: TPS54540

I am using TPS54540DDA in my design. I am giving an input of 12 V (VCC_SELECTED) and taking an output of 5 V (VCC_5_BB).

But under load condition TPS54540 is not able to support more than 0.5 A current. When i am bypassing TPS54540 and supplying 5V

directly from power supply ,my board is working fine. Here load current drawn is 0.8A.

I have attached the schematic file of this part.

Kindly help me on this.....

over 7 years ago

0 Samuel Jaffe over 7 years ago

TI__Mastermind 25590 points

Deepika,

This could be due to instability. Check the switch node to see if you're getting a consistent square wave. If not, check comp values and layout.

This could be due to overheating. Is the part getting very hot? If so, check the layout. Is the powerpad soldered to a large copper GND plane?

-Sam

0 user5774776 over 7 years ago in reply to Samuel Jaffe

Prodigy 10 points

Hi sam,

Thanks for the quick response.

I have attached the cro snapshot of SW pin.I feel its not square wave.Kindly have at a look at the snapshot.

Deepika

0 Samuel Jaffe over 7 years ago in reply to user5774776

TI__Mastermind 25590 points

Deepika,

Is that scope capture taken at light load or full load? That looks like discontinuous conduction mode at light load.

Please also share the layout.

-Sam

0 Deepika Manjunath60 over 7 years ago in reply to Samuel Jaffe

Prodigy 120 points

Sam,

The scope capture is taken at full load.

Deepika

0 Deepika Manjunath60 over 7 years ago in reply to Deepika Manjunath60

Prodigy 120 points

Hi Sam,

Thank you for your help.

My problem is solved.Now tps54540 is able to support load for 12 volt input.

Actually my board is having 3 different grounds which are shorted to each other through ferrite boards.

But as you asked to check whether the powerpad soldered to a large copper GND plane.

So i shorted all the 3 different grounds through a thick wire,which solved my problem.

Deepika

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TPS54540: Issue with TPS54540 to support a load current of 1 amp.