Datasheet

99
[Not recommended for new designs - Use XMEGA A1U series] XMEGA A1 [DATASHEET]
8067O–AVR–06/2013
None.
8. Accuracy lost on first three samples after switching input to ADC gain stage
Due to memory effect in the ADC gain stage, the first three samples after changing input channel must be disre-
garded to achieve 12-bit accuracy.
Problem fix/Workaround
Run three ADC conversions and discard these results after changing input channels to ADC gain stage.
9. The input difference between two succeeding ADC samples is limited by VREF
If the difference in input between two samples changes more than the size of the reference, the ADC will not be
able to convert the data correctly. Two conversions will be required before the conversion is correct.
Problem fix/Workaround
Discard the first conversion if input is changed more than VREF, or ensure that the input never changes more then
VREF.
10. Increased noise when using internal 1.0V reference at low temperature
When operating at below 0C and using internal 1.0V reference the RMS noise will be up 4 LSB, Peak-to-peak
noise up to 25 LSB.
Problem fix/Workaround
Use averaging to remove noise.
11. Configuration of PGM and CWCM not as described in XMEGA A Manual
Enabling Common Waveform Channel Mode will enable Pattern generation mode (PGM), but not Common Wave-
form Channel Mode.
Enabling Pattern Generation Mode (PGM) and not Common Waveform Channel Mode (CWCM) will enable both
Pattern Generation Mode and Common Waveform Channel Mode.
Problem fix/Workaround
12 PWM is not restarted properly after a fault in cycle-by-cycle mode
When the AWeX fault restore mode is set to cycle-by-cycle, the waveform output will not return to normal operation
at first update after fault condition is no longer present.
PGM CWCM Description
0 0 PGM and CWCM disabled
0 1 PGM enabled
1 0 PGM and CWCM enabled
1 1 PGM enabled