ATXMEGA256A3B_10 Datasheet, PDF (96/105 Pages) ATMEL Corporation – 8/16-bit XMEGA A3B Microcontroller

8116H–AVR–08/10
XMEGA A3B
Problem fix/Workaround
If the bandgap is used as reference for either the ADC, DAC and Analog Comparator, the
BOD must not be set in sampled mode.
4. Bandgap measurement with the ADC is non-functional when V_CC is below 2.7V
The ADC cannot be used to do bandgap measurements when V_CC is below 2.7V.
Problem fix/Workaround
Use the bandgap as reference, and measure a known value to be able to calculate the
bandgap value rather than measuring the bandgap directly.
5. BOD will be enabled after any reset
If any reset source goes active, the BOD will be enabled and keep the device in reset if the
VCC voltage is below the programmed BOD level. During Power-On Reset, reset will not be
released until VCC is above the programmed BOD level even if the BOD is disabled.
Problem fix/Workaround
Do not set the BOD level higher than VCC even if the BOD is not used.
6. ADC has increased INL error for some operating conditions
Some ADC configurations or operating condition will result in increased INL error.
In differential mode INL is increased to:
– 6 LSB for sample rates above 1 Msps, and up to 8 LSB for 2 Msps sample rate.
– 6 LSB for reference voltage below 1.1V when VCC is above 3.0V.
– 20 LSB for ambient temperature below 0 degree C and reference voltage below 1.3V.
In single ended mode, the INL is increased up to a factor of 3 for the conditions above.
Problem fix/Workaround
None, avoid using the ADC in the above configurations in order to prevent increased INL
error.
7. DAC has increased INL or noise for some operating conditions
Some DAC configurations or operating condition will result in increased output error.
– INL error is increased up to 35 LSB when VCC < 2.0V
– Enabling Sample and Hold, will increase noise and reduce resolution below 8 bit
Problem fix/Workaround
None, avoid using the DAC in the above configurations in order to prevent increased INL
error.
8. VCC voltage scaler for AC is non-linear
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.
9. Maximum operating frequency below 1.76V is 8 MHz
To ensure correct operation, the maximum operating frequency below 1.76V VCC is 8 MHz.
Problem fix/Workaround
None, avoid running the device outside this frequency and voltage limitation.
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