USB-C PD programmable bench supply

Own work, own time. A PD sink into a four-switch buck-boost stage, on a published four-layer stackup, with the measurements published as they come off the bench.

In progress · not yet fabricated Own work 2026 6 min read

Role

Everything

Ownership

Sole · own time

Scope

Schematic · stackup · layout · bring-up

Stackup

Four layers · published · 90 Ω USB pair

Status

Schematic complete · first layout in review

Fabricate and publish the measured efficiency curve

Not yet fabricated. No photographs until there are.

What it is

A USB-C Power Delivery programmable bench supply: a PD sink negotiating up to 20 V into a four-switch buck-boost stage giving an adjustable 0–24 V output, with an STM32 over USB, a precision current and voltage monitor on I²C, and a small display.

Four layers on a published stackup so the impedance numbers are real, with the USB differential pair routed to a 90 Ω target and length matched.

My current role is fully remote to a German client, which means I write bring-up procedures but do not run them at a bench. That is the gap in my week, and I am closing it on my own time.

Decisions

Kind

Design decision
Problem found
Verification

Design decision U5 · scope

Choosing a project that covers what work does not

Found: Professional work gives me schematic revision, layout to release, and documentation — but not originating a design of my own, and not a bench.
Did: Chose a project that requires all three: originating a schematic on a commercial-grade design, specifying a stackup and its impedance targets myself rather than routing to targets someone else set, and putting my own board on a bench and debugging it.
Result: The gaps are the point. That is why this one is published in progress rather than when it is finished.

Verification

What gets published

The full package: the stackup and impedance report, the manufacturing outputs, and a bring-up and measurement report covering what did not work first time.

I publish the measurements as they come off the bench, including the ones that disagree with the simulation.

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