Dual Power Supply In A Pinch

Recently I needed a dual voltage power supply to test a newly-arrived PCB, but my usual beast of a lab power supply was temporarily at a client’s site. I had a FNIRSI programmable power supply which would have been perfect, but alas, I had only one. While digging around in my junk box I found several USB-C power-delivery “trigger” boards which I bought for an upcoming project. These seemed almost too small for the task at hand, but after a little research I realized they would work quite well.

The ones I had used the Injoinic IP2721 USB-C power delivery chip, commonly used in many of these boards. Mine had been sold pre-configured for certain output voltages, but they were easy to re-jumper to the voltages I needed, +5 VDC  and +20 VDC. The most challenging aspect was physically using them — they are the size of a fingernail. This version had through-hole output pads on 0.1″ centers, so I decided to solder them to the base of a standard MTA pin header. A few crimps later and I was up and running, along with the requisite pair of USB-C cables and power adapters.

For just a few dollars each, these trigger boards are useful to have in your toolbox, both for individual projects and for use in a pinch. We reviewed these modules a couple of years ago, and check out the far more flexible PD Micro that we covered last year.

A Plethora Of Power Delivery Potential

Here at the Hackaday we’ve been enjoying a peculiar side effect of the single-port USB-C world; the increasing availability of programmable DC power supplies in the form of ubiquitous laptop charging bricks. Once the sole domain of barrel jacks or strange rectangular plugs (we’re looking at you Lenovo) it’s become quite common to provide charging via the lingua franca of USB-C Power Delivery. But harnessing those delectable 100W power supplies is all to often the domain of the custom PCBA and firmware hack. What of the power-hungry hacker who wants to integrate Power Delivery in her project? For that we turn to an excellent video by [Brian Lough] describing four common controller ICs and why you might choose one for your next project.

A superb illustration from the TS100 Flex-C-Friend documentation

[Brian] starts off with a sorely-needed explainer of what the heck Power Delivery is; a topic with an unfortunate amount of depth. But the main goal of the video is to dive into the inscrutable hoard of “USB C trigger boards.” Typically these take USB on one side and provide a terminal block on the other, possibly with a button or LED as user interface to select voltage and current. We’ve seen these before as laptop barrel jack replacements and TS100 power supplies but it’s hard to tell which of the seemingly-identical selection is most suitable for a project.

The main body of the video is [Brian’s] detailed walkthrough of four types of trigger boards, based on the IP2721, FUSB302, STUSB4500, and Cypress EZ-PD BCR. For each he describes the behaviors of it’s particular IC and how to configure it. His focus is on building a board to power a TS100 (which parallels his TS100 Flex-C-Friend) but the content is generally applicable. Of course we also appreciate his overview of the products on Tindie for each described module.

For another angle on Power Delivery, check out this series of posts by [jason cerudolo], a perennial favorite. And don’t miss his classic project, the USB Easy Bake Oven.