Goal

Make a flexible but barebones test platform to get a digital power supply working

Architecture

Topology

A four switch buck/boost power stage is chosen due to it’s flexibility in operating as either a standard buck or boost by keeping two of the switches in a fixed state. The added hardware for a BUBO is minimal compared to just a buck or boost, and it gives added flexibility once we are ready to take the project further.

MCU Selection

Sticking with the STM32 line as that is what we are using for the rest of the car. Although the L433 does have a timer peripheral with many features useful for digital power, it does not have a high resolution timer. This would limit the switcher to very low switching frequencies. Instead we will use the STM32F344, which has an HRTIM and includes a rich set of peripherals specifically designed for mixed signal, digital power applications.

Boards

In all other projects, the MCU has always been on a controller board. Still undecided if we want to have a controller board for this too. There are fewer benefits since there is only 1 board that would use this MCU, and if we want to do JLC assembly (so I can work on it over coop) the cost savings of transferring one MCU between multiple boards are not that big.

Given that using JLC assembly is under consideration, all parts will be from the JLC library, with preference for Basic and Preferred parts to avoid loading fees. All SMT components will also be on one side to use JLC’s economic assembly service.

Circuit