WEBENCH® Tools/LM5085: Circuit shuts off after 20 V Vin

Antonio Reis

Part Number: LM5085

Tool/software: WEBENCH® Design Tools

The input (Vin) varies from 33V to 55 V and the output required is 5 V.

The power system shuts down with voltages above 19 V.

The circuit functions in a standalone breakout pcb.
When I transferred the circuit to the integrated PCBA, the circuit does not function even so all components are identical to the ones on the breakout board.

Anyone had similar problems?

Your help is appreciated.

over 5 years ago

0 Iven Su over 5 years ago

TI__Expert 8245 points

Hi,

Could you please upload a clearer schematic, that would be helpful, thanks.

0 Antonio Reis over 5 years ago in reply to Iven Su

Prodigy 20 points

0 Iven Su over 5 years ago in reply to Antonio Reis

TI__Expert 8245 points

Hi,

If your circuit functions in a standalone breakout pcb, it mean the schematic is OK, so you may need check the below items:

1. Check input/output power trace are wide enough so that the current and heat can go through.

2. Check the load applied on standalone and integrated PCB, if the load is different, you may need to change inductor and current limit values.

3. Check other layout difference between the two PCBs, device may work abnormally if the layout is bad.

Power management

Power management forum

WEBENCH® Tools/LM5085: Circuit shuts off after 20 V Vin