Designing a power supply for the new trainer board

Many of you are using the Microcontroller Trainer v2 that I designed a couple of years ago. Those of you who develop projects with larger current demands understand the limitations of the LM317 linear voltage regulator that I used on that board, and have shared a desire for more current capabilities. I’ve been working on the next (and likely final) revision of the trainer board, aiming for it to become a permanently available product, and as part of this I wanted to design an enhanced power supply option.

So far, here’s how the design is going. The main trainer board itself will have a basic power supply included. This supply will once again be based on linear regulators, and will once again provide for a 5v and 3.3v rail. Current handling will be increased to roughly 1 amp per power rail, but I’m not stopping there.

For those of you who want more from a power supply ,I’m designing an enhanced power supply option. The enhanced power supply will be an add-on card for the trainer board, and will provide the following features

Support for an 18650 Lithium Polymer battery – so you’re no longer chained to the workbench

Real-time voltage and current monitoring of both power rails, with a separate microcontroller with integrated high-resolution color IPS display

Higher efficiency through the use of switching regulators

As I started to design the power supply, I looked at other products on the market. One that caught my eye in particular was the Adafruit Powerboost 1000c. Adafruit chose to use a Texas Instruments TPS6109x boost converter module on the output of a LiPO charge controller, which gives about 2 amps of capacity. This was perfect for what I was trying to accomplish with a 1 amp load per rail. Here is the datasheet for the TPS module from TI

I’ve designed a couple of prototype power supplies using this module, and so far, it’s never worked. I can’t even get it working a little bit. I’ve cleaned the slate, and designed another supply from scratch, and I’m currently waiting on the stencil to arrive so I can assemble the unit. This was my first time having my board house create a purple PCB, the color is pretty cool – very similar to the boards coming out of OSHPark.

Unfortunately, the stencils aren’t here yet. The best I can get out of DHL is ‘shipment on hold’ – so maybe the PCBs made it through customs but the stencil didn’t ? I really don’t know.

I’ll be sure to keep you informed of the results of the power supply testing – maybe it’ll work this time? I’ll likely be live-streaming on twitch while assembling it, so be sure to tune and and watch the work in progress!