ATXMEGA256A3_1012 Datasheet, PDF (100/134 Pages) ATMEL Corporation – 8/16-bit XMEGA A3 Microcontroller

36.1.2 rev. B
XMEGA A3
• Bandgap voltage input for the ACs can not be changed when used for both ACs simultaneously
• VCC voltage scaler for AC is non-linear
• ADC has increased INL error for some operating conditions
• ADC gain stage output range is limited to 2.4 V
• ADC Event on compare match non-functional
• Bandgap measurement with the ADC is non-functional when VCC is below 2.7V
• Accuracy lost on first three samples after switching input to ADC gain stage
• Configuration of PGM and CWCM not as described in XMEGA A Manual
• PWM is not restarted properly after a fault in cycle-by-cycle mode
• BOD will be enabled at any reset
• DAC is nonlinear and inaccurate when reference is above 2.4V or VCC - 0.6V
• DAC has increased INL or noise for some operating conditions
• DAC refresh may be blocked in S/H mode
• Conversion lost on DAC channel B in event triggered mode
• EEPROM page buffer always written when NVM DATA0 is written
• Pending full asynchronous pin change interrupts will not wake the device
• Pin configuration does not affect Analog Comparator Output
• NMI Flag for Crystal Oscillator Failure automatically cleared
• Writing EEPROM or Flash while reading any of them will not work
• Crystal start-up time required after power-save even if crystal is source for RTC
• RTC Counter value not correctly read after sleep
• Pending asynchronous RTC-interrupts will not wake up device
• TWI Transmit collision flag not cleared on repeated start
• Clearing TWI Stop Interrupt Flag may lock the bus
• TWI START condition at bus timeout will cause transaction to be dropped
• TWI Data Interrupt Flag (DIF) erroneously read as set
• WDR instruction inside closed window will not issue reset
1. Bandgap voltage input for the ACs cannot be changed when used for both ACs
simultaneously
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.
2. VCC voltage scaler for AC is non-linear
The 6-bit VCC voltage scaler in the Analog Comparators is non-linear.
8068T–AVR–12/10
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