Atmel Evaluation-Board AT90USBKey AT90USBKey AT90USBKey-2 Hoja De Datos
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AT90USBKey-2
Using the AT90USBKey
2-6
AT90USBKey Hardware User Guide
7627A–AVR–04/06
2.2
Power Supply
2.2.1
Power Supply Sources
The on-board power supply circuitry allows two power supply configurations:
from USB connector
from battery connector
USB powered When used as a USB device bus powered application, the AVRUSBKey can be directly
powered via the USB VBUS power supply line.
Battery powered
The external battery connector should be used when the AT90USBKey is used as a
USB host. This mode allows the AT90USBKey to provide a 5V power supply from its
VBUS pin.
USB host. This mode allows the AT90USBKey to provide a 5V power supply from its
VBUS pin.
– Need of a female battery clip
– Input supply from 8 up to 15V DC (min. 100mA)
Figure 2-2 . Power supply schematic
VCC3
IN
1
GND
2
OUT
3
U5
LM340
VBUS
VBAT
D4
LL4148
LL4148
-
C16
4.7uF
R19
124k 1%
124k 1%
U3out=1.25*(1+(R15+R18)/R19)
R18
100k 1%
D3
LL4148
C17
220nF
VCC3
5V
R15
100k 1%
MTA
Ext power supply
1
2
J8
C18
100nF
OUT
1
IN
2
GND
3
OUT
4
FAULT
8
SHDN
7
CC
6
SET
5
U4
LP3982
C15
33nF
D6
LL4148