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TPS63011 PCB Layout

Other Parts Discussed in Thread: TPS63011, BQ25505

I'm working on a design that will include a TPS63011 as well as a BQ25505. I'm placing parts now and before I get too far I'd appreciate some feedback on my parts and via placement, as well as the ground pours.

I've read the design note and seen the example layout where the power pad and "signal" grounds are brought to vias near the inductor and then 2 isolated ground pours are placed at the input and output caps. In looking at the design I'm wondering if the top ground could get tied in the upper left hand corner of the TPS63011 (in my picture) instead of at the 2 vias next to the inductor? That would allow the inductor to be placed closer to the part and you would be able to have a solid ground pour on the top layer that connects everything. By doing that the input ground would have a longer path so it might be better to isolate the input cap ground and have it go through the vias rather than around the circuit.

On a separate note I didn't see any guidelines on connecting VIN to VINA. The reference schematics show them as isolated but in the example layout they are just directly connected. Perhaps it could be taken that the VINA is connected in somewhat of a single point connection rather than through a copper pour?



  • Basically it is highly important to create a common star point between analog gnd AGND and power ground PGND, which is recommended close to the device' AGND as shown by the EVM layout. With the via size you use, one should be sufficient as well. Is the via size the smallest you can use?

    You can tie VIN & VINA together, what is the typical use case. When you face a very noisy input rail, you can place a small blocking cap to VINA (as shown by the EVM example) to generate a filtered voltage for the devices control logic supply.
  •  Yeah, after I walked away and came back and looked at the design I saw the logic of how parts were placed due to power ground being on C1/C2. I've moved things around and started the layout which I think is much better. I see I've got EN tied to VINA but VINA isn't tied to VIN currently.  The supply will be coming from a battery but when the BQ25505 is charging I'm not sure how noisy that rail will be. It would be good insurance to keep the blocking cap but removing EN from VINA would force me to do a little shuffling. What do you think is the lesser of 2 evils; keeping VINA tied to EN with a blocking cap, or just tying them all together?

    The vias are somewhat large (14/28). I started with a 2 layer board but I switched to a 4 layer this morning because I wanted some better power and ground planes. All proto houses can handle 14/28 vias so I like to start with that to keep prototyping costs down.