4 years, 8 months ago.

when I supply 7.5 V in Vin only 2.5 V come out of Vu?

screen is no showing anything due to low voltage.

Question relating to:

Rapid Prototyping for general microcontroller applications, USB and 32-bit ARM® Cortex™-M0 based designs

1 Answer

4 years, 8 months ago.

Vu is the 5V from the USB mini socket. It will only carry 5V as long as the USB is plugged in. The small voltage you measure is due to leak currents. In case Vin is used as main power for mbed while also needing 5V for other electronics then an external 5V regulator should be added between Vin and the other devices.

Accepted Answer

On addition to Wim's comment... Please refer to schematic -> https://developer.mbed.org/media/uploads/chris/mbed-010.2-schematic.pdf.

This schematic is linked from zmbed NXP LPC11U24 Handbook Page.

posted by Tedd OKANO 25 Jan 2017