ATxmega128D4-AU ATMEL [ATMEL Corporation], ATxmega128D4-AU Datasheet - Page 121

• Manufacturer Part Number: ATxmega128D4-AU
• Description: 8/16-bit Atmel XMEGA D4 Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

8135L–AVR–06/12
2. VCC voltage scaler for AC is non-linear
Figure 34-1. Analog Comparator Voltage Scaler vs. Scalefac.
3. ADC gain stage cannot be used for single conversion
4.
If the Bandgap voltage is selected as input for one Analog Comparator (AC) and then
selected/deselected as input for another AC, the first comparator will be affected for up to
1 µs and could potentially give a wrong comparison result.
Problem fix/Workaround
If the Bandgap is required for both ACs simultaneously, configure the input selection for both
ACs before enabling any of them.
The 6-bit VCC voltage scaler in the Analog Comparators is non-linear.
Problem fix/Workaround
Use external voltage input for the analog comparator if accurate voltage levels are needed
The ADC gain stage will not output correct result for single conversion that is triggered and
started from software or event system.
Problem fix/Workaround
When the gain stage is used, the ADC must be set in free running mode for correct results.
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 130ksps, and up to 8LSB for 200ksps 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
3.5
2.5
1.5
0.5
3
2
1
0
0
T = 25°C.
5
10
15
20
25
SCALEFAC
30
35
40
45
50
55
XMEGA D4
60
65
3.3V
2.7V
1.8V
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