ATMEGA406_0607 Datasheet, PDF (249/263 Pages) ATMEL Corporation – 8-bit Microcontroller with 40K Bytes In-System Programmable Flash

Figure 36-3. CM Offset with unbalanced cells.
ATmega406
Problem Fix/Workaround
Avoid getting unbalanced cells by using the internal cell balancing FETs.
3. Voltage Reference Spike
The Voltage Reference, VREF, will spike each time a temperature measurement is started
with the Voltage-ADC.
Problem Fix/Workaround
An accurate temperature measurement could be obtained by doing 10 temperature conver-
sions immediately after each other. The first 9 results would be inaccurate, but the 10th
conversion will be correct.
Figure 36-4 on page 250 illustrates the spike on the Voltage Reference when doing 10 tem-
perature conversions in a row (external decoupling capacitor of 1µF).
2548E–AVR–07/06
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