TPS65251: Schematic Revew : TPS65251

KIM Andy

Expert 2530 points

Part Number: TPS65251

Hello

One of my clients is using the TPS65251 for this project.

It seems to me that it was applied with the right design values.

Could you please take one more review?

I will deliver the corresponding schematic file.

<<5 schematics deleted>>

over 6 years ago

0 Vental Mao over 6 years ago

TI__Expert 5745 points

What's the value of your output cap? And the C1408=4.7uF for V3V is better. The feedforward cap(C1370,C558，C559) looks a little big, but it related to the Cout.

And what's your load? Iout1=0.448A,Iout2=0.121A, Iout3=0.368A?

0 KIM Andy over 6 years ago in reply to Vental Mao

Expert 2530 points

Hello
Thank you for quick response.

Use two TPS65251s.

The load on the first circuit is 0.145A, 0.68A, 0.01A.
The load on the second circuit is 0.448A, 0.121A, 0.368A.

Thanks again for your quick response.

0 Vental Mao over 6 years ago in reply to KIM Andy

TI__Expert 5745 points

Hi What's the value of the output cap? i didn't see them in your schematic.

0 KIM Andy over 6 years ago in reply to Vental Mao

Expert 2530 points

OUTPUT CAP is as follows.

<<schematic deleted>>

0 Vental Mao over 6 years ago in reply to KIM Andy

TI__Expert 5745 points

Looks good. What you need to care is the components in the comp pin, it seems that the value you set is a little small, which will decrease the cross frequency and have a risk about the loop stable. So pls re-calculate the value with the equation in the datasheet.

0 Zhao Ma over 6 years ago in reply to KIM Andy

TI__Genius 15135 points

Hi,

Due to the output capacitance is big, during startup, there is big inductor inrush current may trigger OCP, so i suggest:

1. Suggest to enlarge C1404 and C1409 and C1410 (SSx cap) to 22nF. --> increase soft start time.

2. Reduce Rlimit1 (R977) to 75k, Rlimit2 (R1279) =Rlimit3 (R979) =100kohm. --> increase OC limit threshold.

Besides, the VIN1 (C1399&C1400 ) and VIN2 (C1401&C1402) and VIN3 (C1403&C1378) caps should be layouted closely to VINx pin.

0 Zhao Ma over 6 years ago in reply to Vental Mao

TI__Genius 15135 points

Hi, Vental

I think the compensation is ok, :)

Thanks for your support.

0 KIM Andy over 6 years ago in reply to Vental Mao

Expert 2530 points

Hello.

Thank you very much to the quick response.

Thanks a lot to help.

0 KIM Andy over 6 years ago in reply to Zhao Ma

Expert 2530 points

Hello.

Thank you very much to the quick response.

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TPS65251: Schematic Revew : TPS65251