ATXMEGA256A3_1012 Datasheet, PDF (111/134 Pages) ATMEL Corporation – 8/16-bit XMEGA A3 Microcontroller

8068T–AVR–12/10
XMEGA A3
Figure 36-4. Analog Comparator Voltage Scaler vs. Scalefac
T = 25°C
3.5
3
2.5
3.3 V
2.7 V
2
1.8 V
1.5
1
0.5
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65
SCALEFAC
Problem fix/Workaround
Use external voltage input for the analog comparator if accurate voltage levels are needed
3. ADC has increased INL error for some operating conditions
Some ADC configurations or operating condition will result in increased INL error.
In signed mode INL is increased to:
– 6LSB for sample rates above 1Msps, and up to 8 LSB for 2Msps sample rate.
– 6LSB for reference voltage below 1.1V when VCC is above 3.0V.
– 20LSB for ambient temperature below 0 degree C and reference voltage below 1.3V.
In unsigned mode, the INL error cannot be guaranteed, and this mode should not be used.
Problem fix/Workaround
None, avoid using the ADC in the above configurations in order to prevent increased INL
error. Use the ADC in signed mode also for single ended measurements.
4. ADC gain stage output range is limited to 2.4 V
The amplified output of the ADC gain stage will never go above 2.4 V, hence the differential
input will only give correct output when below 2.4 V/gain. For the available gain settings, this
gives a differential input range of:
– 1x gain:
– 2x gain:
– 4x gain:
– 8x gain:
– 16x gain:
– 32x gain:
– 64x gain:
2.4 V
1.2 V
0.6 V
300 mV
150 mV
75 mV
38 mV
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