Hey, I'm trying to run the NXP LPC11U24 for a battery powered mobile device in which power is a concern. The battery and charger I currently have supply 3.7V and I wish for this to power the device through the VB pin, which requires 3.3V, so that the mbed can consume the minimum amount of power while it is in deep sleep. The issue I am having is that when the mbed is restarted or turned on, it requires the Vin pin to be powered with at least 4.5V so that the code can be loaded to run otherwise the mbed is non functional until it receives this power. After this occurs the Vin pin no longer needs to be powered.

Does anyone know of a way that I can get the mbed to load the code when it is only powered by a 3.7V battery?

Assuming you are using a Lithium Ion Battery, check out the LiPo Boost Converter from sparkfun https://www.sparkfun.com/products/10255. It will take your 3.7V and bring it up to the 5V you need for the Vin of the mbed.

Also if power consumption is of concern, check out http://mbed.org/cookbook/Power-Management. Gives some tips on turning off the ethernet and USB interface that cuts power consumption nearly in half (meaning your battery will power your mbed twice as long!).