TPS552872: Design Verification

Hi Jagan,

You can use TPS552892 webench for TPS552872 simulation, but the compensation parameters can only be used for reference. After you finish your schematic design, you can send the schematic and BOM to us to review.

Regards,

Mulin

Hi Mulin,

I have attached the schematics of the design for your reference.

Please let me know if anything needs to be changed.

Regards,

Jagan

Hi Mulin Yuan, 

We’re supplying 12V and 5V as inputs to generate a 5V output. In this case, will the VCC voltage, generated by the internal LDO from VIN or VOUT, function as expected, or do we need to supply EXTVCC separately?

My understanding is that EXTVCC is primarily used to reduce the load on VIN or VOUT. Could you also confirm whether the internal switchover logic between VIN, VOUT, will operate correctly under these conditions?

Also, in our design, the overall power requirement is about 500–600 mA, with a worst-case peak of 1–1.5 A at 5V output when powered from 12V, and up to 0.5A/0.9 A when powered from 5V (USB power). Could you please suggest a buck-boost regulator that supports a lower output current, as the TPS552872 might be oversized for our needs?

Regards, 

Mk

Hi Mulin Yuan, 

It would be great if this detail could be added to the datasheet for future reference, please consider including it. 

Regards, 

Mk

Hi Mukesh,

I will look into this and reply to you later.

Regards,

Mulin

Hi Mk,

Thank you for your advice about datasheet explanation. We will consider it in future update. About your schematic, below is my feedback:

1.Is there any load dumping requirement for this application? Notice that EN is 20V rated.

2.Change R500 to 0ohm.

3.Change R506 to 0ohm

4.Can you help provide part number of output cap? I can help evaluate the compensation parameters.

5.Add RC filter in ISN and ISP pin. Also, 0.68ohm resistor is too small. You can use a 20mohm resistor here.

6. Follow layout guideline.5432.TPS55289 Layout Guideline.pdf

Regards,

Mulin

Hi Mulin Yuan, 

Thanks for the review, 

Could you please update us on the query below?

Mukesh k said:

Also, in our design, the overall power requirement is about 500–600 mA, with a worst-case peak of 1–1.5 A at 5V output when powered from 12V, and up to 0.5A/0.9 A when powered from 5V (USB power). Could you please suggest a buck-boost regulator that supports a lower output current, as the TPS552872 might be oversized for our needs?

Regards, 

Mk

Hi Mulin,

1. There is no load dumping requirement

2,3. I have changed R500,R506 to 0 Ohm

4. The output cap part number is - MSASE32MAB5107MPNA01 (100uF) and GRM033R6YA104KE14D (0.1uF). Please assist in calculating compensation values for this.

5. I have added the RC filter as you suggested. The max output current is 500mA for our application. I have set the current limit at 750mA (using 68mOhm resistor, previously 680mOhm due to miscalculation) based on equation 18 in DS. Please let me know if this is appropriate.

Hello Jagannathan,

Please excuse the delay in response, but there is a public holiday for the expert today. Please expect an answer tomorrow.

Best regards,
Brigitte

Hi Mk,

You can consider TPS63070. 

Regards,

Mulin

Hi Rajan,

Recommended compensation parameters: R503=5k, C361=15nF, C360 NC.

Regards,

Mulin