TPS552892: Schematic/Layout Review

Hello, to add to this: I removed any copper beneath the inductor. Also, I added an optional snubber circuit (2.2R w/ 2.2nF cap) on the underside. Thanks.

Hi Desmond,

Thank you for reaching out. TPS55289-Q1 is used for automotive and TPS552892 is used for non-auto.

About the schematic,

1.Recommend to add RC snubber in SW1 and SW2. 

2.There is only one output cap in Vout. Is there more in load side?

Layout is poor to me. Please follow this layout guideline:7271.TPS55289 Layout Guideline.pdf

Desmond Lagace said:

I have the feedback path from Rfbt and Rfbb running beneath the IC, is this not advisable?

If there is a full GND layer between top layer and signal layer, no issue.

Desmond Lagace said:

(Is it advisable to place a capacitor across Rfbb to smooth out the signal on FB?)

Not advisable. Avoid introduce pole and zero to affect loop stability.

Regards,

Mulin

Thank you. Here is updated layout:

I tried to follow the layout guideline as closely as possible, and there is indeed more 22uF capacitors on the load side. There is ground plane on inner layer and bottom layer, and I moved the resistors/capacitors around to mimic the guideline. I also added a 10nF capacitor to DITH/SYNC to ground; is this required? I had it grounded before.

Also, here is updated schematic, I placed optional snubber circuitry on bottom side:

Hi Desmond,

Due to bandwidth limitation, I will look into this later.

Regards,

Mulin

Hi Desmond,

 I think the layout improves a lot but still several points to modify.

1.  GND of Cin and Cout should be connected with GND pin with below.

2. pin 1, 2, 5, 6 should also be connected to AGND.

3. thermal vias connection.

Regards,

Mulin