DRV8432: DRV8432 layout

dengshan yang

Part Number: DRV8432

hi,

we use DRV8432 for our design to drive TEC, our design like your reference below, we found no layout notes in your datasheet, so we have some questions.

1. about the input PWM_A/PWM_B/PWM_C/PWM_D, do we need to route them as differential pair?

2. about OUTPUT, do we need to route them as differential pair,too?

Jerry

over 4 years ago

0 Ryan Kehr over 4 years ago

TI__Guru 55605 points

Jerry,

There are layout guidelines in section 10 of the datasheet. Typically, the PWM is going to be lower in frequency (<500kHz), so routing the inputs as differential pairs is not critical like it would be in a high speed circuit.

Also not critical for outputs.

Regards,

Ryan

0 dengshan yang over 4 years ago

Prodigy 155 points

hi Ryan,

Thanks for your quick reply, another question about DRV8432 layout, in the DRV8432EVM, we see that, the OUT_A and OUT_B is surrounded by ground plane, so do OUT_C and OUT_D, see picture below, is that necessary? due to that our load is 12V/12A TEC , so we want to increase the width for heavy load as soon as possile, can we ignore the surrounded ground plane?

Jerry

0 Ryan Kehr over 4 years ago in reply to dengshan yang

TI__Guru 55605 points

Jerry,

It is not necessary on the output side.

Regards,

Ryan

0 dengshan yang over 4 years ago in reply to Ryan Kehr

Prodigy 155 points

hi Ryan，

one question more, due to the load 12V/12A TEC, so about the OUT_A/B/C/D, how to route them, what attention we need to pay? can you recommend?

Jerry

0 Dingmin Xu over 4 years ago in reply to dengshan yang

Intellectual 490 points

HI,

I'm not an expert on that, but I think the ground plane might be used to reduce EMI emission. Through 500kHz is not a very high frequency, the edge of the waveform can be really steep and cause EMI problem.

Thanks!

0 Ryan Kehr over 4 years ago in reply to Dingmin Xu

TI__Guru 55605 points

All,

If LC filter is used as it is on the layout you reference above, the edge rates will be significantly reduced before output cable to TEC. I agree, with no filter, edge rates on this device are very fast and any GND around output traces would be helpful.

Jerry,

EVM can handle 15A. If you follow EVM design guideline, it will work fine for your application.

Regards,

Ryan

0 dengshan yang over 4 years ago in reply to Ryan Kehr

Prodigy 155 points

hi Ryan,

I found PCB materials as below, it's suggested that FR-4 with 2oz copper on top and bottom, if we design 6 layers PCB, can we reuce copper to 1 oz on top and bottom, the attached file is our design file, could you help double check?

TEC module REV_1.0.PcbDoc.zip

TEC module REV_1.0.pdf

0 Ryan Kehr over 4 years ago in reply to dengshan yang

TI__Guru 55605 points

I believe you are using DRV8432 which has a top-side heat sink. If that is the case, the weight of the copper in the board is not important for thermal heatsinking like it would be for the DRV8412 which has a pad exposed at the bottom of the package and heat sinking is done with the copper in the board.

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DRV8432: DRV8432 layout