LMR38020: pcb layout review

Muki

Prodigy 210 points

Part Number: LMR38020

Tool/software:

Hi guys,

I've attached two different layouts for LMR38020 at 3.3V 0.5A output

Design 1

Design 2

Schematic

If i reduce the width of the switching track in design 1, can it be used ?

The test pcb will be 4 layers - 2oz / 1oz / 1oz / 2oz - The inner layers will be GND and 3.3V

do let me know if any other changes are recommended

Thanks & Regards,

Muki

5 months ago

0 Onkar Bhakare 5 months ago

TI__Genius 14586 points

Hi Muki

Assigned engineer will take a look and get back to you.

Thank you

Regards

Onkar Bhakare

0 Muki 5 months ago in reply to Onkar Bhakare

Prodigy 210 points

Hi Onkar,

Understood

I'm attaching a screenshot for the engineer's reference

LMR38020 layout

Thanks & Regards,

Muki

+1 Pramanik Patel 5 months ago in reply to Muki

TI__Expert 4525 points

Hi,
Can you please let me know the following things:

1) Input voltage

This is required to get value of inductor and to check the stability in Power Designer.

With respect to layout:

Yes, it is better to reduce SW polygon.
Try to sense Vout as close as possible to the load.
If possible, keep Vout plane bigger than this (Not a must but recommended)

Thanks,

Pramanik Patel

0 Muki 5 months ago in reply to Pramanik Patel

Prodigy 210 points

Hi Pramanik,

1 - The input voltage will vary from 42V to 58V, with 51.2V nominal

Layout changes :

a - will make SW polygon smaller

b - "Try to sense Vout as close as possible to the load" - do you mean the input to the feedback pin 5 ?

c- will make Vout plane as big as possible

WEBENCH Design - webench.ti.com/.../SDP.cgi

Thanks & Regards,

Muki

+1 Pramanik Patel 5 months ago in reply to Muki

TI__Expert 4525 points

Hi,

Inductor value chosen is correct.

For answer to B:

Thanks,

Pramanik Patel

0 Muki 4 months ago in reply to Pramanik Patel

Prodigy 210 points

Hi Pramanik,

That clarifies things. Thank you for the detailed image

Immensely grateful,

Mukesh

+1 Pramanik Patel 4 months ago in reply to Muki

TI__Expert 4525 points

Hi,

Let me know if you need further assistance.

Thanks,

Pramanik Patel

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LMR38020: pcb layout review