TPS564247: tps564247 schematic and layout check

Hossam Moghrabi

Prodigy 210 points

Part Number: TPS564247

Tool/software:

Hello,

I have finished designing my design and need you to check it for me.

Here are the images: https://slow.pics/c/5rXOFMiB

Quick notes:

- input is 12v for both switchers, one outputs 3.3v and the other 5v.

- feedback signal is taken directly near the output from a separate trace and via, surrounded by ground vias.

- it is 4 layers, the two inner layers are ground pouts while bottom is mainly ground with some traces like feedback.

- output and input caps has ground pours, which are stitched to below plains by lots of vias as shown.

- there are ground vias under the switcher IC itself.

- power and switch node traces are thick and wide, with no vias.

- switch node is short, there is no trace or pour of top layer under the inductor.

- Cff = 150pF 0603 cap for both switchers.

- output caps are: 3x22u 1206 + 6x 10u 0805 + 2x 100n 0402 + 10uF elec cap for damping.. all ceramic are x5r. 5v has 5x 10u 0805 caps instead of 6 less than 3.3v.

kindly check the design and tell me what to do or if it is good.

I require low ripple and noise, less than 10mv p-p at 3 amps if possible.

thanks

2 months ago

0 Shipeng Cheng 2 months ago

TI__Expert 8530 points

Hi,

The layout looks good.

Thanks.

0 Hossam Moghrabi 2 months ago in reply to Shipeng Cheng

Prodigy 210 points

hello,

thanks for your reply.

so there is nothing to fix in this layout? what about components choices and placement? 150pf cff 0603 is good?

please inform me of anything that can enhance the performance.

0 Shipeng Cheng 2 months ago in reply to Hossam Moghrabi

TI__Expert 8530 points

Yes, no issue need to be adjust now.

0 Hossam Moghrabi 2 months ago in reply to Shipeng Cheng

Prodigy 210 points

hello,

ok nice, i will go for that design.

however, i have another one for another product seen here: https://slow.pics/c/mIOsPdg4

another layout for same design is here: https://slow.pics/c/fqLrOhA4

i shown layout and feedback trace, still not finished.

please give me your opinion on both examples.

thanks

0 Shipeng Cheng 2 months ago in reply to Hossam Moghrabi

TI__Expert 8530 points

Hi Hossam,

It's better for me to review your layout with schematic. Now I can only say the picture looks not bad. But I have a concern here. It seems your load is not on this board, so the inductance from this board to your load will limit the transient response behavior.

Thanks.

Shipeng

0 Hossam Moghrabi 2 months ago in reply to Shipeng Cheng

Prodigy 210 points

hello

schematic here: https://slow.pics/c/WdWPFSjt

parts are:

22u ceramics: 1206 x5r (x3 per converter)

10u ceramics: 0805 x5r (x6 per converter)

inductor: 2.2u for 5v and 1.5u for 3.3v

Cff = 150pf 0603 ceramic

output caps have 1x 10u elec. cap with high esr (3ohms) for damping.

input rails both share 3x220u polymer caps in addition to their own ceramic caps shown.

as for load, it will be connected by 10cm wires which are thick 18 gauge wires. originally the board was to be connected to the target device directly as plug in but this is not possible design wise.

I don't anticipate huge transients at all, it is a retro game console which is rated at 5v 2a maximum... runs at 50 or 60hz (pal or ntsc) which may sip power at those frequencies but not gonna be 0% to 100% load.

also check updated layout: https://slow.pics/c/2BqGuZyI

thanks

0 Shipeng Cheng 2 months ago in reply to Hossam Moghrabi

TI__Expert 8530 points

Hi Hossam,

The schematic and layout looks good.

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TPS564247: tps564247 schematic and layout check