Hi,
Can you give us more information for example, how do you know that the LPC812 does not work when the VDD is 2.6V?
Pls use the LED blinky example in SDK and impress 2.6V to the VDD, does the LED still toggle?
If the BOD is disabled, I do not think there is special configuration if you use low voltage VDD.
In 2.6V, if you press Reset, can the board work?
BR
XiangJun Rong