atxmega192a1-au ATMEL Corporation, atxmega192a1-au Datasheet - Page 92

• Manufacturer Part Number: atxmega192a1-au
• Description: 8/16-bit Xmega A1 Microcontroller
• Manufacturer: ATMEL Corporation

8067M–AVR–09/10
5. Sampling speed limited to 500 ksps for supply voltage below 2.0V
6. ADC Event on compare match non-functional
7. Bandgap measurement with the ADC is non-functional when VCC is below 2.7V
8. Accuracy lost on first three samples after switching input to ADC gain stage
9. The input difference between two succeeding ADC samples is limited by VREF
Problem fix/Workaround
Keep the amplified voltage output from the ADC gain stage below 2.4 V in order to get a cor-
rect result, or keep ADC voltage reference below 2.4 V.
The sampling frequency is limited to 500 ksps for supply voltage below 2.0V. At higher sam-
pling rate the INL error will be several hundred LSB.
Problem fix/Workaround
None.
ADC signalling event will be given at every conversion complete even if Interrupt mode (INT-
MODE) is set to BELOW or ABOVE.
Problem fix/Workaround
Enable and use interrupt on compare match when using the compare function.
The ADC can not be used to do bandgap measurements when VCC is below 2.7V.
Problem fix/Workaround
None.
Due to memory effect in the ADC gain stage, the first three samples after changing input
channel must be disregarded to achieve 12-bit accuracy.
Problem fix/Workaround
Run three ADC conversions and discard these results after changing input channels to ADC
gain stage.
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.
–
–
–
–
–
–
–
16x
32x
64x
1x
2x
4x
8x
gain:
gain:
gain:
gain:
gain:
gain:
gain:
300
150
2.4
1.2
0.6
75
38
V
V
V
mV
mV
mV
mV
XMEGA A1
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