SAM3A4C Atmel Corporation, SAM3A4C Datasheet - Page 1452

• Manufacturer Part Number: SAM3A4C
• Manufacturer: Atmel Corporation

48.2.4
48.2.4.1
48.2.4.2
48.2.4.3
48.2.5
48.2.5.1
1452
SAM3X/A
Analog to Digital Converter (ADC)
JTAG Boundary
ADC: First conversion after sleep
ADC: Last Conversion Error
ADC: Wrong First Conversions
JJTAG Boundary: PC0/ERASE
In sleep mode, first converted data incorrect after Wakeup.
One or more channels must be converted using sleep mode, a dummy channel as first channel
of the series can be used.
In sleep mode, last converted data incorrect before Shutdown.
One or more channels must be converted using sleep mode, a dummy channel as first channel
of the series can be used.
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.
Three workarounds are possible :
1) 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.
2) Perform a dummy conversion on a single ended channel on which an external voltage of
ADVREF/2 (+/-10%) is applied. And 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.
3) 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). And 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.
In JTAG Boundary Scan mode, the PIO PC0 which is by default the ERASE pin may erase the
Flash content if the pin is set to high level.
Do not use PC0/ERASE (or tie to 0) or set PC0/ERASE at high level during a time lower than
150 ms in Boundary JTAG Scan mode or program the Flash after using this mode.
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
11057A–ATARM–17-Feb-12