TPS61088: TPS61088

Xhaseem Muwakanya

Part Number: TPS61088

Hello all,

I purchased a TPS61088EVM-677 board, tested it by playing around with different output voltages, and finally agreed to use 4.5V3A output for my heating project design.

I went on to design the schematics referring to the EVM schematics and artwork, programmed for 4.5V3A output, However my board design can only provide 2.5A which is not

enough for my load to heat up to our desired temperature. The EVM worked well with about 4.5V3.3A. (I am pretty new to power designs)

Below is part of my schematics and artwork capture.

Thank you!

over 4 years ago

0 Helen chen over 4 years ago

TI__Mastermind 40080 points

Dear Sir,

Please check my below feedback:

Schematic:

1. change R18 to 15k.

Pcb Layout:

Please refer to the TPS61088 EVM layout(check below picture, AGND and the pGND should be seperated): pour enough GND copper plane below the IC.

0 Xhaseem Muwakanya over 4 years ago in reply to Helen chen

Prodigy 120 points

Hi Helen,

Thank you for the reply, I forgot to mention that I have tried changing R18 to 17K and15K already.

Yes I think have had enough pour, however I wasn't able to separate AGND & PGND due to some board design limitations I had at the moment.

Please, I want you to confirm that not separating AGND from PGND is the main problem here before I go ahead with printing a new PCB.

Thanks,

Xhaseem

0 Helen chen over 4 years ago in reply to Xhaseem Muwakanya

TI__Mastermind 40080 points

Dear Sir,

It is very simple to seperate the AGND and the PGND, you can just refer to the TPS61088 EVM board placement below. Put the Cout as close to the output pin as possible. Then pour the AGND and the PGND in the same way.

0 Xhaseem Muwakanya over 4 years ago in reply to Helen chen

Prodigy 120 points

Hi Helen,

Yes I have fixed the artwork, bringing the output capacitors as close as possible and separating AGND from PGND.

I will revert after testing the new board.

Thanks,

Xhaseem

0 Helen chen over 4 years ago in reply to Xhaseem Muwakanya

TI__Mastermind 40080 points

Good Luck!

0 Xhaseem Muwakanya over 4 years ago in reply to Helen chen

Prodigy 120 points

Hi Hellen,

I have finally tested my 4.5V5A board. I used a recommended schematics from webench power designer for 4.5V5A Output.

Apparently I can only get 2.4A to 2.6A.

Please have a look at my schematics and artwork!

Thank you!

0 Xhaseem Muwakanya over 4 years ago in reply to Xhaseem Muwakanya

Prodigy 120 points

Hello,

I forgot to say that my load (heating element) is 1ohm. It is kind of a sealer.

Thank you!

0 Helen chen over 4 years ago in reply to Xhaseem Muwakanya

TI__Mastermind 40080 points

please use R18=10k，C=4.7nF for a double check，thanks.

0 Xhaseem Muwakanya over 4 years ago in reply to Helen chen

Prodigy 120 points

Hi Helen,

Yes I tried 10k and maximum I can get is 2.5A

Do you mean Capacitor C19?

Thank you,

0 Helen chen over 4 years ago in reply to Xhaseem Muwakanya

TI__Mastermind 40080 points

Yes, I mean C19=4.7nF

0 Xhaseem Muwakanya over 4 years ago in reply to Helen chen

Prodigy 120 points

Hi Helen,

Apologies, my trace width from the battery supply to TPS61088 wasn't wide enough to provide all the maximum current (battery located a bit too far from TPS61088 due to lack of space on PCB)

Having jumped a thick wire to the Input directly from the battery, it did give me an awesome 4.5V4.8A finally! :)

Please wait to lock up this thread as we might have some bit of inquiries during testing for a couple of days (presumably 3days).

Thanks again

0 Helen chen over 4 years ago in reply to Xhaseem Muwakanya

TI__Mastermind 40080 points

Great!

Its really a good news. I'll lock this post one weeks later :)

0 Xhaseem Muwakanya over 4 years ago in reply to Helen chen

Prodigy 120 points

Hi Helen,

Thanks a lot for your help. We have successfully done all our required tests and everything now works perfect!

Lesson learned: ARTWORK is most important in Power management (Trace Width-Current Calculator is useful).

Cheers,

Xhaseem

0 Helen chen over 4 years ago in reply to Xhaseem Muwakanya

TI__Mastermind 40080 points

Yes, this is a very good lesson learn.

Good Luck!

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TPS61088: TPS61088