Atmel AT01080: XMEGA E Schematic Checklist [APPLICATION NOTE]
42087A
−
AVR
−
04/2013
4
1.2
External analog reference connections
Atmel AVR XMEGA E proposes one ADC using internal references or an external analog reference (AREFA on PORTA
or AREFD on PORTD).
The following schematic checklist is only recommended if the design is using the external analog reference. If the
internal reference is used, the circuit is not necessary.
Figure 1-2. External V
REF
schematic.
Table 1-2. External analog reference checklist.
Signal name
Recommended pin connection
Description
AREFA
1.0V to AV
CC
-0.6V for ADC
Decoupling/filtering capacitors 100nF
(1)(2)
and 4.7µF
(1)
External reference from A
REF
pin on PORT A
AREFD
1.0V to AV
CC
-0.6V for ADC
Decoupling/filtering capacitors 100nF
(1)(2)
and 4.7µF
(1)
External reference from A
REF
pin on PORT D
GND
Ground
Notes:
1. These values are given only as a typical example.
2.
Decoupling capacitor should be placed close to the device.
2.
External Reset Circuit
The external reset circuit is connected to /RESET pin only if the external reset function is used.
Figure 2-1. External reset circuit example schematic.
