1.5A switch, 33kHz — the workhorse buck/boost controller
The MC34063ECD-TR is a DC-DC converter IC from STMicroelectronics that handles both step-up (boost) and step-down (buck) topologies with a single 1.5A internal switch. The 33kHz switching frequency is low by modern standards — you will need a larger inductor than a 500kHz part, but the trade-off is simpler layout and lower radiated noise. The input range spans 3V to 40V, making it suitable for unregulated wall warts, battery packs, or 12V/24V industrial rails.
Adjustable output, positive or negative rail
The output is adjustable from a 1.25V reference up to 38V, and the configuration can generate a positive or negative rail. That flexibility — plus the absence of synchronous rectification — means the external diode selection matters: use a Schottky with a Vf below 0.5V at the peak switch current to keep efficiency above 75% in a typical 12V-to-5V buck. The single-output design is straightforward; no multi-rail sequencing needed.