SAM3SD8C Atmel Corporation, SAM3SD8C Datasheet - Page 1129

• Manufacturer Part Number: SAM3SD8C
• Manufacturer: Atmel Corporation

43.2.2
43.2.2.1
11090A–ATARM–10-Feb-12
Analog-to-Digital Converter (ADC)
ADC: wrong first Conversions
The first conversions done by the ADC may be erroneous if the maximum gain (x4 in single
ended or x2 in differential mode) is not used. The issue appears after the power-up or if a con-
version has not been occured for 1 minute.
Four workarounds are possible :
1) Perform an automatic calibration. The next conversions will be correct for any channels and
any settings. Note that this calibration needs to be performed if no conversion has occured for 1
minute or for a new chip start-up.
2) Perform 16 dummy conversions on one channel (whatever conditions used in term of setup of
gain, single/differential, offset, and channel selected). The next conversions will be correct for
any channels and any settings. Note that these dummy conversions need to be performed if no
conversion has occured for 1 minute or for a new chip start-up.
3) Perform a dummy conversion on a single ended channel on which an external voltage of
ADVREF/2 (+/-10%) is applied. Use the following conditions for this conversion: gain at 4, offset
set at 1. The next conversions will be correct for any channels and any settings. Note that this
dummy conversion needs to be performed if no conversion has occured for 1 minute or for a
new chip start-up.
4) Perform a dummy conversion on a differential channel on which the two inputs are connected
together and connected to any voltage (from 0 to ADVREF). Use the following conditions for this
conversion: gain at 4, offset set at 1. The next conversions will be correct for any channels and
any settings. Note that this dummy conversion needs to be performed if no conversion has
occured for 1 minute or for a new chip start-up.
Problem Fix/Workaround
SAM3S8/SD8
1129