Hello
As you know, if a PIC, or in general a CMOS chip, has no power supply connected, the maximal voltage allowed on its I/O is limited to ~0.3V.
But how to handle a PIC (with no power supply connected) with an USB bus or SPI bus attached to another device????
Ok, one solution would be to use the USB power supply to supply current to the PIC, so that the USB D+ and D- couldnt harm the I/O pins.
But imagine, the power supply needed exceeds the max 500mA of the USB?
What would be the solution to protect the I/O pin?
Thank you!
As you know, if a PIC, or in general a CMOS chip, has no power supply connected, the maximal voltage allowed on its I/O is limited to ~0.3V.
But how to handle a PIC (with no power supply connected) with an USB bus or SPI bus attached to another device????
Ok, one solution would be to use the USB power supply to supply current to the PIC, so that the USB D+ and D- couldnt harm the I/O pins.
But imagine, the power supply needed exceeds the max 500mA of the USB?
What would be the solution to protect the I/O pin?
Thank you!