Not my field of expertise so excuse my ignorance ...Your +5v will take to to come up too, so typically you will be fine else add 3 diodes in series between the 5v rail and the 3.3v rail to help out.
Would it be possible to use some sort of Zener Diode circuit so the Pico's 3V3 is fully provided before the 5V rail exceeds what the RP235X's GPIO (FT) 3.63V limit ?
Code:
.-----------------------------. .-----------------------------. | 5V Rail | | 5V Rail | |-----------------------------| |-----------------------------| 5V | __-------| 5V | __-------| 4V | _ _ _ _ _ _ _ __-- | 4V | _ _ _ _ _ _ _ __-- | 3V | __-- : : | 3V | __-- | 2V | __-- : : | 2V | __-- : | 1V | __-- : : | 1V | __-- : | 0V |__-- : : | 0V |__-- : | `-----------------------------' `-----------------------------'Code:
.-----------------------------. .-----------------------------. | 3V3 Rail - Diode drop | | 3V3 Rail - Zener | |-----------------------------| |-----------------------------| 5V | : : | 5V | : | 4V | _________| 4V | _____________| 3V | __-- | 3V | __-- | 2V | __-- : | 2V | __-- : | 1V | __-- : | 1V | __-- : | 0V |______-- : | 0V |__-- : | `-----------------------------' `-----------------------------' |<---- T = 20 ---->| |<-- T = 16 -->|Statistics: Posted by hippy — Mon Aug 04, 2025 3:24 pm