358
8331B–AVR–03/12
Atmel AVR XMEGA AU
Figure 28-2.
Differential measurement without gain.
28.3.2
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 the gain stage is used, the differential
input is first sampled and amplified by the gain stage before the result is fed into the ADC. 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 28-3.
Differential measurement with gain.
28.3.3
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
ADC7
•
•
•
•
•
•
GND
INTGND
½x - 64x