LM25085: Voltage drop according to load

Hyerim Kwon

Prodigy 20 points

Part Number: LM25085

Hi.

I'd like to receive technical advice on LM25085.

[Design conditions]

- Vin : 18-20V

- Vout : 15V/8A

When there is no load, it operates normally at Vout 15V, but when it starts to flow more than 500mA, a voltage drop occurs.

(If 1A flows, it drops to 7V.)

This is the webench that I referred to in the design.

https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=85832605ABC2F19F

wonder what caused the voltage drop. Help me.

over 3 years ago

0 Iven Su over 3 years ago

TI__Expert 8245 points

Hi,

Could you please first check the input source current limit? Also, could you please upload your schematic/layout/waveforms(Pgate, switching node and Vout... ), these will be helpful, thanks.

0 Hyerim Kwon over 3 years ago in reply to Iven Su

Prodigy 20 points

Thank you for your reply.

Which part is wrong?

0 Iven Su over 3 years ago in reply to Hyerim Kwon

TI__Expert 8245 points

Hi,

The power traces are too narrow, please change them wider. You should use 40mil wide / 2oz thick copper per 1A current.

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LM25085: Voltage drop according to load