Two TPS63021 design

Javo Barragan

Prodigy 90 points

Other Parts Discussed in Thread: TPS63021, TPS63020

Hi! I'm working with 2 TPS63021 in my design. One, it is for 5V outputs (IC1) and the other is for 3.6V (IC2).

I have problem when the 2 ICs are working. The IC2 works perfect but the IC1 has a short circuit in inductance pins.

When i don't use IC2, IC1 works perfect.

I supose the problem is about the location of my inductors.

Can u help me with my design? Is it correct the location of the both inductors?

-IC1 is on bottom side and IC2 is on top side.

Thank so much,

Javier

over 8 years ago

0 Sabrina over 8 years ago

TI__Expert 8420 points

TPS63021 has a fixed output voltage Vout=3.3V. You should use the TPS63020 (adjustable version of the same IC) to get 5V and 3.6V output voltage
Can you please post your schematic?

0 Javo Barragan over 8 years ago in reply to Sabrina

Prodigy 90 points

Sorry, i used the TPS63020. I wrote wrong.
This is my schematic, but i think the problem is on the board.

Thanks for your help!

0 Sabrina over 8 years ago in reply to Javo Barragan

TI__Expert 8420 points

The schematic looks fine, I would like to review your layout but it is hard with this picture.

Could you please send me each layer, separately, and the silk screen of top and bottom layer in PDF format?

I would also like to see the whole power stage components and not half of them.

0 Javo Barragan over 8 years ago in reply to Sabrina

Prodigy 90 points

AVL16-01_BOT.pdf AVL16-01_TOP.pdf AVL16-01_silk_bottom.pdf AVL16-01_silk_top.pdf

0 Javo Barragan over 8 years ago in reply to Javo Barragan

Prodigy 90 points

Sabrina is it enough or do u need more info? Thanks

0 Sabrina over 8 years ago in reply to Javo Barragan

TI__Expert 8420 points

Thank you for the layout:

I could not find the vias on the output caps of IC10. How are they connected to ground?

0 Javo Barragan over 8 years ago in reply to Sabrina

Prodigy 90 points

yes sabrina, it is connect to ground.

0 Sabrina over 8 years ago in reply to Javo Barragan

TI__Expert 8420 points

Ok then please send me the layout pdf files were I can also see all the polygones.
This GND plane is not visible on the layout you posted on your previous post

0 Javo Barragan over 8 years ago in reply to Javo Barragan

Prodigy 90 points

This is the .brd file, may be it is more useful to see this. If u prefer a pdf file, please tell me.

Thanks!AVL16-01.brd

0 Sabrina over 8 years ago in reply to Javo Barragan

TI__Expert 8420 points

Thank you for the layout file.

I would use a direct connect between the polygons ant the components, not a relief connect. This makes for example the connection to ground, or the switch node connection very thin which is not recommended from an electrical point of view.

For IC1 the ground connection is not good. First it is very thin. Besides I would definitly not connect the ground underneath the inductor. It generates coupled noise in the ground. I think you should find a way to rearrange the layout, so that you can place vias and connect the caps' ground directly to the IC ground on the top layer. Moreover I would not place traces (the one routing D1) under the switch node.

How do you detect the short in the inductance pin of IC1? is the device damaged or do you use the same device when you test it without IC2?

Can you show a scope plot of Vin and Vout in both cases:

IC2 works perfect and IC1 has a short

I don't une IC2 , IC1 works perfect

This would help me to debug your design

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Two TPS63021 design