TPS552872: Schematic Review

Hi Desmond,

Thank you for reaching out.

1.Change R78 to 150kohm.

2.Change L7 to 4.7uH.

3.Add a 0402 0.1uF cap in Vout pin.

4.Recommend to reserve two more 22uF cap in Vout.

5.Add a capacitor parallel to R75 and C50.  After output cap part number is selected, optimize compensation parameters

6.Recommend to reserve RC snubber position in SW1 and SW2. Refer to EVM.

7.Follow layout guideline.2084.TPS55289 Layout Guideline.pdf

Regards,

Mulin

Thanks.

Any minimum load requirement for this?

Hi Desmond,

TPS552872 has 3.3A minimum average inductor current limit. So with minimum input voltage, it has 10*3.3*0.95/20=1.56A maximum load capability,

Regards,

Mulin

Thanks. Should I supply VCC with external 5 V and ground EXTVCC, since in some cases both VIN and VOUT will be 20V, and this may burn excess power in the internal LDO?

Hi Desmond,

There is no need to choose external 5V for VCC power. Internal circuit is well designed for Vin 3-36V and Vout 0.8-22V occasion.

Regards,

Mulin

Thank you. 

Due to current requirements, I have switched to the TPS552892, with the schematic largely the same. Is it OK to use a 6.8uH (Isat = 7A) inductor, if I can't use a 4.7uH due to space/part availability?

Hi Desmond,

It is ok. But the bandwidth will reduce and response speed will be slower. You need to evaluate the transient performance by bench test.

Regards,

Mulin