LPC824 from external power source

[essamnamouz]

I am trying to power the LPC824 Xpresso v2 board using an external power supply instead of powering from USB.  I can use USB for power while programming, but then I want to be able to run it without the USB plugged in after it is programmed.

It is not clear where and how much voltage I supply.  I tried 5V to the Vin pin but that did not work.  The built in LED came on, but no firmware was running.  When I disconnected this and provided power via USB it works fine again.

[jeremyzhou]

Hi essamnamouz,

Thank you for your interest in NXP Semiconductor products and 

for the opportunity to serve you.

According to datasheet, you can find that the VCC level can't exceed the 4.6 V (Fig 1), and on the LPC824 Xpresso v2 board, it integrates the voltage-transferring circuit which is used to output the 3.3 V from the feeding 5V.

Have a great day,

TIC

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