STK526 datasheet(13/40 Pages) ATMEL

13 / 40 page

Using the STK526

2-12

STK526 rev. B Hardware User Guide

7709B–AVR–07/08

VBUS Detection The board also implements a VBUS detection on a generic I/O. A low-power (50µA)

voltage divider (/2) is connected from VBUS to PortC bit 2 pin. The VBUS presence is

detected with a high level on the MCU pin.

VBUS Power Source Moreover, even if not selected as primary power source, VBUS powers the on-board

3.3V regulator (through a diode to avoid current being supplied to USB Host) in order to

get 3V3 voltage in any condition (this allows to power the dataflash at any time, or to

allow a USB Bus-powered operation with all the board at 3.3V.

However, this feature can make current flowing from VBUS to some board peripherals

even if an alternate power source is used to power the board. That may lead to

unwanted extra-consumption, so it can be disabled by cutting the configuration pad.

Figure 2-10 . Configuration Pad Location

Note:

See Section “Configuration Pads”, page 24 for details.

STK526 Datasheet(PDF) 13 Page - ATMEL Corporation