[cctalk] Re: RP2350 5V Input Tollerant Pins

I have not studied the RP2350 datasheet closely (and I'm definitely not an EE), but as I understand it, the caveat here is that 5V tolerance only exists while the device is fully powered (IOVDD at 3V3).  At lower supply voltages (e.g. during startup), digital I/O pins may be damaged by voltages higher than 3.3. The topic is discussed in more depth here, and in linked threads: https://forums.raspberrypi.com/viewtopic.php?t=375118 To bring this somewhat back around to cctalk, I faced this issue when designing my console adapter for the PDP-11/05 (github <https://github.com/jaylogue/pdp1105-console-adapter-v2>). It is based on the  rPI Pico (RP2040), which has a similar limitation.  I wanted the device to be able to be powered from the 11/05 itself.  But at power on, the supply voltage races with the SERIAL OUT (TTL) line, and always looses due to the time it takes for the onboard 3V3 regulator to stabilize.  Since I cared more about simplicity than power efficiency or speed, I went with a simple voltage divider rather than a level shifter. --Jay On 7/30/25 07:04, Martin Bishop via cctalk wrote: