LPC1769 power question

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by CharlesM on Sat Feb 08 21:56:17 MST 2014
I'm using a LPC1769 based LPCxpresso board. The LPC Link board is attached and no jumper connections have been severed or altered from the default factory configuration.

If I apply +5V from a 7805 regulator to pin J6-2 (EXT_POWX) of the LPC1769 board, what should be done with pin J6-28 (VIO_3V3X)? Do I need an additional 3.3V regulator to power VIO_3V3X as well, or can that pin be left open?


The schematics indicate it is an input when the board is externally powered via EXT_POWX (as opposed to self-powered through USB), but I'm not sure how the attached LPC-Link board affects the VIO_3V3/VIO_3V3X signals.