PMP7390 tweaked design failure TPS40170

Joshua Winkler

Other Parts Discussed in Thread: PMP7390

I tried to re-configure the PMP7390 design to fit a long/narrow PCB, but cannot get it to work. I've attached the schematic and board images I used below, I hope someone can point me to my mistake. I get 3.3V from the VDD pin of the TPS40170, but the input to the TPS2511 is only reading 0.58V.

Red traces on top, blue traces on bottom, all components are on the top.

over 8 years ago

0 Joshua Winkler over 8 years ago

Prodigy 30 points

0 JohnTucker over 8 years ago in reply to Joshua Winkler

TI__Guru**** 191445 points

I am not surprised you are having difficulties with that layout. Generally speaking, you cannot connect the nodes with simple narrow copper etch traces. For the circulating power paths you must use copper fill areas and you wi;; probably need a dedicated ground plane as well. Did you closely look at the original PCB design for PMP7390?

0 Joshua Winkler over 8 years ago in reply to JohnTucker

Prodigy 30 points

Full disclosure, I'm an ME doing my best to play an EE for this project. I did study the PMP7390 design before learning Eagle, drawing the schematic, and spending days trying different layouts for the board that would fit my physical size restraints. I am confused as to how I can get bigger traces when the TCP40170 nodes are so tightly arranged? Are you suggesting a 4 layer PCB as the solution so more copper can be used to handle the power?

0 JohnTucker over 8 years ago in reply to Joshua Winkler

TI__Guru**** 191445 points

Yes, I would be inclined to go with a 4 layer PCB.

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PMP7390 tweaked design failure TPS40170