WEBENCH® Tools/LM5116: Add load burned

hukee

Part Number: LM5116

Tool/software: WEBENCH® Design Tools

This 27V dc is the input to LM5116 to get output of 12V. When it outputs current 0.7A is ok。When I added 55w bulb, lm5116 burned down. lm5116 output 0.

I use the LM(2)5116 Quick Start Component Calculator tool to calculate。

lm5116_NG.zip

over 6 years ago

0 Frank De Stasi over 6 years ago

TI__Guru 71985 points

It is hard to say what might be going on.
Do you have any waveforms at the time that the unusual behavior occurs?

0 hukee over 6 years ago in reply to Frank De Stasi

Prodigy 60 points

VSW

High mosfet Vg

Low mosfet Vg

VCHB

27V Input ，12V Output，Load 0.7A

0 hukee over 6 years ago in reply to hukee

Prodigy 60 points

POWER V1.pcb

PCB File ，using pads。

0 hukee over 6 years ago

Prodigy 60 points

Normal vcc output is 7.2v, it fails output 5v。

Today, use the following parameters, mosfet CSD18563，VCCX 0ohm to gnd，the DEMB pin is 10k to gnd，Cboot 1uf，L1 10uH。

Connected to the power supply, the inductor makes a sound。

0 Frank De Stasi over 6 years ago in reply to hukee

TI__Guru 71985 points

The waveforms look a little strange. Be sure that the scope probe has a good ground connection.
If VCC is not correct then either an external component is shorted or the device is damaged.
Be sure that the DAP is well soldered to the ground plane.

What are you trying to achieve with the wires shown in the image??

0 hukee over 6 years ago in reply to Frank De Stasi

Prodigy 60 points

Thank you for your reply！

Yes,My oscilloscope is low level device。

The bottom of ic solding ok。

the wires is gnd and VIN，There is a problem with the pcb layout。

I don't understand why that damage with increasing the current.

Mosfet Drive capability？ Loop Compensation ？

VSW

V ramp pin

0 Frank De Stasi over 6 years ago in reply to hukee

TI__Guru 71985 points

It is possible that your layout is at fault. I can not read your PCB file; if you could make snapshots of the layout
I could look at it.

0 hukee over 6 years ago in reply to Frank De Stasi

Prodigy 60 points

top

bottom

0 Frank De Stasi over 6 years ago in reply to hukee

TI__Guru 71985 points

It looks like your bottom ground plane is somewhat broken up with traces.
I would try to move those traces so the the ground plane is more continuous.
Also, I would try to use more ground plane on the top and more ground vias near the power
components.
The data sheet gives good guidance as to PCB layout for the power components.

Power management

Power management forum

WEBENCH® Tools/LM5116: Add load burned