LPC55xx GPIO

[ianbenton]

Are the GPIO inputs 5V tolerant?
If not, are there protection diodes from input to Vdd and Vss, so that it would be possible to connect a 5V input simply by using a current limiting resistor and allowing the upper protection diode to conduct (as is normally done in logic gates)?

[gusarambula]

Hello ianbenton,

The LPC55XX GPIOs are not 5V tolerant. Only the VBUS pin is 5V tolerant. For more details please refer to the LPC55XX Datasheet.

My apologies for the inconvenience.

Regards,
Gustavo

[ianbenton]

Not inconvenient if I find out now.

Only inconvenient if I find out AFTER I've made my pcb.

I don't see any spec for the maximum current through the protection diode.

Also, the spec implies that the maximum voltage on a GPIO pin is 3.6V regardless of the value of Vdd. i.e  the pin could be taken 1.8V above Vdd if Vdd were 1.8V.

Is this correct?

[ianbenton]

Found the maximum voltage spec elsewhere in the datasheet, but not the maximum current through the protection diodes.

[gusarambula]

Hello ianbenton,

The maximum current trough the protection diodes is not characterized in the datasheet. There are some pin static characteristics including input current which would be the recommended limit.

Regards,
Gustavo