If your introduction to digital electronics came more years ago than you’d care to mention, the chances are you did so with 5V TTL logic. Above 2V but usually pretty close to 5V is a logic 1 ...

Previously, [Andrew] used level shifter chips for interfacing the RP2040 with 5V systems, but he’s rebuilt a few designs of his without level shifters for the sake of this experiment.

Low-leakage LDO in TSMC 40 ULP eFlash to supply logic and analog domains (up to 5.5V input supply) with embedded Level Shifters Applicable to automotive, industrial. Designed for extended ...