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247
8210C–AVR–09/11
Atmel AVR XMEGA D
Figure 21-2.
Differential measurement without gain.
21.3.2
Differential Input with Gain
When differential input with gain is enabled, all input pins can be selected as positive input, and
input pins 4 to 7 can be selected as negative input. When gain is enabled, the differential input is
first sampled and amplified by the gain stage before the result is converted. The ADC must be in
signed mode when differential input with gain is used.
The gain is selectable to 1/2x, 1x, 2x, 4x, 8x, 16x, 32x, and 64x gain.
Figure 21-3.
Differential measurement with gain.
21.3.3
Single-ended Input
For single-ended measurements, all input pins can be used as inputs. Single-ended measure-
ments can be done in both signed and unsigned mode.
The negative input is connected to internal ground in signed mode.
+
-
ADC0
ADC3
ADC0
ADC15
•
•
•
•
•
•
GND
INTGND
+
-
ADC4
ADC7
ADC0
ADC15
•
•
•
•
•
•
GND
INTGND
½x - 64x