TPS54225EVM-538: Trouble Configuring EVM to Output 5V

Mitchell

Part Number: TPS54225EVM-538
Other Parts Discussed in Thread: TPS54225

Hi Team,

My customer is having trouble getting the TPS54225EVM to output 5V. They changed R1 to 121kOhm, but no feedfoward cap has been added. Also, the inductor hasn't been changed.

They also changed R1 to 73.2K, 49.9K, and the EVM does output 2.5V and 3.3V. Can you help us understand why they are having trouble at 5V?

FYI - the input voltage is 12V.

Thanks,
Mitchell

over 5 years ago

0 Gavin Wang (Zejing) over 5 years ago

TI__Expert 3480 points

Mitchell ,

Pls try a 4.7uH inductor and try again.

Gavin

0 Daniel Li14 over 5 years ago

TI__Mastermind 27030 points

Hi Mitchell:

sorry that we don't have EVM on hands right now, so we can't duplicated the issue right now

but one potential cause is the EVM board 22uF is 6.3V votlage rating, when output is 5V , output cap(C3216X5R0J226M085AC) only has 30% capacitance , so it may make the circuit unstable. is that possilbe to let ctm try 22uF 10V or 16V votalge rating MLCC to see whether the issue can be solved.

we will apply the EVM, and if it doesn't work, pls let us know.

Thanks

Daniel Li

0 FEI ZHU over 5 years ago in reply to Daniel Li14

Prodigy 60 points

I tried 15V rating Capacity, it doesn't work.

In my board, I had 4.7uH inductor and 25V rating cap, it doesn't work.

I didn't try 4.7uH in TI EV board since the footprint is smaller than Inductor I had.

Hope you can get EV Board to have a try. and let me you know what's your solution.

Thanks!

Fei Zhu

0 Mitchell over 4 years ago in reply to FEI ZHU

TI__Expert 4915 points

Hi Team,

Do you have any updates to this?

Thanks,
Mitchell

0 Iven Su over 4 years ago in reply to Mitchell

TI__Expert 8245 points

Hi,

Could you please upload your schematic and layout of TPS54225 part, we are having a try on EVM board, thnaks.

0 FEI ZHU over 4 years ago in reply to Iven Su

Prodigy 60 points

So do you mean the EVB board you had can work at 5V output? why my EVB can't work at 5V?

See my schematics as following, I will send you PCB layout file tomorrow.

In my board, the R465 is 0ohm, and R467 is not installed.

Thanks!

Fei

0 Yuchang Zhang over 4 years ago in reply to FEI ZHU

TI__Mastermind 18510 points

Hi,

Team are trying to check on EVM.

Could you please describe more about the trouble of output 5V? Vout is not stable or no Vout, or others...? work at no loading or ...? Change Vin voltage whether there is difference happen? if some waveform are shown will be helpful.

By the way, C401 in your schematic is mounted or not? if already mount it, try to remove it to retry.

Yuchang

0 FEI ZHU over 4 years ago in reply to Yuchang Zhang

Prodigy 60 points

When I remove the C401, it has 5V output.

Thanks lot!

By the way, could explain why the cap affect 5V output?

Regards!

0 Yuchang Zhang over 4 years ago in reply to FEI ZHU

TI__Mastermind 18510 points

I suppose 1uF cap is too big that may cause too long time to charge FB to target value.

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TPS54225EVM-538: Trouble Configuring EVM to Output 5V