LM5156: LM5156 schematic review

Kevin Huang8

Genius 4515 points

Part Number: LM5156

Tool/software:

Hi Team,

I experience Boost mosfet instability, need your command for schematics

Vin: 37-57V
Vout: 54V, Iout: below 0.6A
Attached is the picture of Vin 54V, Iout 0.1A & 0.5A

Vin 54V, Iout 0.1A

Vin 54V, Iout 0.5A

2 months ago

0 Mounika Girish 2 months ago

TI__Intellectual 2426 points

Hello Kevin,

Thank you for using e2e forum.

Could you please attach the filled out https://www.ti.com/tool/download/SNVC224 to this thread? This would be the most efficient workflow for us to do a schematic review.

Best regards,

Mounika

0 Kevin Huang8 2 months ago in reply to Mounika Girish

Genius 4515 points

Hi Mounika,

LM5156 Quickstart Calculator for Boost Converter Design V1_1_1.xlsx

0 Mounika Girish 2 months ago in reply to Kevin Huang8

TI__Intellectual 2426 points

Hi Kevin,

Is the waveform attached is SW node signal? Can you please mark it in the schematic.

Can you Zoom in and see the width of the switching pulse.We assume that the device is in pulse skip mode because of the min ON time.

Best regards,

Mounika

0 Kevin Huang8 2 months ago in reply to Mounika Girish

Genius 4515 points

Hi Mounika,

Because the waveform is unstable, I captured a few pictures as attached.

0 Mounika Girish 2 months ago in reply to Kevin Huang8

TI__Intellectual 2426 points

Hi Kevin,

I realised, Vin = Vout = 54V. In this case the device is not switching and skips the cycle. So this is the right behaviour

Best regards,

Mounika

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LM5156: LM5156 schematic review