My PiNAS project part 36 - Point-of-load voltage regulator for the Pi

tl;dr: I swapped feedback resistors on a TI eval board to get 5.15v 5A for my RPi5
Hand soldered 0603 resistors. Not perfect, but not bad. imho
0603 is 1.6mm x 0.8mm

Project recap: This is for a RPi5 based NAS, with SAS and 10GbE connectivity.

Details for this part:
The add-on cards use 3.3, 5 and 12v from a 400w Delta ATX PSU.
The RPi5's AC PSU uses "USB Power Delivery" to negotiate a voltage, but the minimum is 5.1v, so I can't just use the 5v from the ATX PSU.
There are DC-DC buck modules all over Amazon but the quality is unknown and I don't feel safe powering my $90 Pi with a no-name circuit. I've had a good experience using a Texas Instruments buck converter for another project, so I went looking for some TI chips that could take 12v and output 5.1v at 5A.
I landed on the TPS5450. After putting together a BOM, I noticed the total wasn't far off from the price of their evaluation board that already has a complete circuit.
The only caveat is that it's spec'd for 5v, so I had to swap out the voltage divider feedback resistors.
The TPS5450's voltage reference (Vᵣ) is 1.221
The equation for Vout (Vₒ) is:

Vₒ = Vᵣ (1 + R₁/R₂)

I splurged and got some high precision, thermally stable, thin film resistors with 0.1% tolerance. They're green :D
I wanted to shoot for 5.15 to give headroom for any cable losses.

Given the available values, I settled for 5.162

Vᵣ = 1.221
R₁ = 10.2k
R₂ = 3.16k
Vₒ = 5.162

Input is 12v from a sata power connector.
Output is a barrel connector that attaches to a barrel-to-USB-C adapter.
The eval board has no mounting holes, so for now I've printed a little holder for it. It uses friction to hold the board.

Success! No more "Undervoltage" warnings in syslog (When I tried using the 5v ATX rail).
The TI chip is very efficient so it doesn't need a heatsink. The output is 5.165 vs the theoretical 5.162, but given that the internal Vref has a 1.5% accuracy, that's actually really good :D

Quick holder I made in Solidworks to hold the TPS5450EVM-254 buck converter evaluation board from Texas Instruments. The layer lines actually provide little catch points as you press the board in.
.STEP file:
https://drive.google.com/file/d/1WiMFuNONA1O3eA-31kQoTfFFzLlPx6xt

cat tax