TPS552872-Q1: schemetic R and C recommendations

Hi Daoyan,

1. May I know what is the customer and their application?

2. What is the input voltage range, output voltage and max output current?

3. Can you reply with the complete schematic? What is the part number of the inductor and the output capacitors?

4. For your questions, if output current limit is not used, you can connect ISP and ISN to Vout directly.

BRs,

Bryce

Hi Bryce,

Thanks for the help here. And sorry for delay because China National Day vacation.

This is connected to Spare battery of automotive head unit, then fix output to 3.8V, no current limit.

Attached is the detailed schematics, can you please help below two questions?
1. Is there a problem with the circuit design?
2. How to set above R and C parameters?

Customer is layout now, they are in a hurry for the review feedback, thanks a lot for the help!

Buckboost_TI_tps552872-q1_design_review_20231008_A.pdf

Best regards,

Daoyan

Hi Bryce,

Thanks a lot for the help here, customer has updated all according to your advices. Please help check below schematic.

TPS63020-Q1 is for 3 batteries in series applications, (Vin up to 4.8V), the Default application use is TPS552872-Q1 with 4 cells in series, Vin up to 6.4V.

And their output current requirements is 3A or 4A, so TPS552872-Q1 maybe enough here, right?

Thanks a lot!

Best regards,

Daoyan

Hi Daoyan,

The new picture is too vague, I can't see it clearly, can you show the pdf or more clear picture?

BRs,

Bryce

Hi Bryce.

What about below picture? If not, can you please try to open initial Email sent by customer below? Thanks a lot and let me know if any questions.

_EXTERNAL_ 回复_ TPS552872-Q1 for 车载Buckboost参数如何配置.msg

Best regards,

Daoyan

Hi Daoyan,

If their output current requirements is 3A or 4A, so TPS552872-Q1 is not enough here, they need to change to TPS552892-Q1.

The output feedback resistors are wrong, the current Vout is set at 2.4V.

BRs,

Bryce

Hi Bryce,

Thanks for the feedback,

Regarding average inductor current limit is 3.3A min of TPS552872-Q1, if customer output current is 3A, may I ask why TPS552872-Q1 is not enough here?

I'm afraid 8A will be too overspec and will cause confusion to customer, thanks a lot!

Best regards,

Daoyan

Hi Daoyan,

For example, if Vin=3.6V, the input current should be larger than 3.8V*3A/0.95/3.6V=3.33A. And if the output current is 4A, the input current should be larger than 3.8V*4A/0.95/3.6V=4.44A.

BRs,

Bryce

Hi Bryce,

Understood, customer has changed R16 to 46.2K in below picture.

And they wonder whether surrounding C R parameters should also change if they updated to p2p TPS552892-Q1, or which C R parameters should change, can you please help it?

Thanks a lot!

BR,

Daoyan