AT90USBKey Hardware User Guide
AT90USBKey Hardware User Guide
AT90USBKey Hardware User Guide
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Using the <strong>AT90USBKey</strong><br />
2.2 Power Supply<br />
2.2.1 Power Supply Sources<br />
2-6 <strong>AT90USBKey</strong> <strong>Hardware</strong> <strong>User</strong> <strong>Guide</strong><br />
7627A–AVR–04/06<br />
The on-board power supply circuitry allows two power supply configurations:<br />
from USB connector<br />
<br />
from battery connector<br />
USB powered When used as a USB device bus powered application, the AVRUSBKey can be directly<br />
powered via the USB VBUS power supply line.<br />
Battery powered The external battery connector should be used when the <strong>AT90USBKey</strong> is used as a<br />
USB host. This mode allows the <strong>AT90USBKey</strong> to provide a 5V power supply from its<br />
VBUS pin.<br />
– Need of a female battery clip<br />
– Input supply from 8 up to 15V DC (min. 100mA)<br />
Figure 2-2 . Power supply schematic<br />
J8<br />
2<br />
1<br />
MTA<br />
Ext power supply<br />
VBUS<br />
D3<br />
LL4148<br />
D4<br />
LL4148<br />
D6<br />
LL4148<br />
5V<br />
2<br />
7<br />
3<br />
LP3982<br />
33nF<br />
C15<br />
U3out=1.25*(1+(R15+R18)/R19)<br />
- C16<br />
4.7uF<br />
U4<br />
1<br />
IN OUT<br />
4<br />
SHDN OUT<br />
8<br />
FAULT<br />
CC<br />
GND<br />
6<br />
5<br />
SET<br />
220nF<br />
C17<br />
VBAT<br />
1<br />
2<br />
U5<br />
IN<br />
GND<br />
LM340<br />
OUT<br />
R15<br />
100k 1%<br />
100k 1% R18<br />
R19<br />
124k 1%<br />
3<br />
100nF<br />
C18<br />
VCC3<br />
VCC3
Change language