Datasheet
Data Sheet ADAS3022
Rev. B | Page 37 of 40
Bits Bit Name Description
[5:4] SEQ Channel sequencer. Allows for scanning channels sequentially from IN0 to INx. INx is the last channel converted prior
to resetting the sequence back to IN0 and is specified by the channel selected in the INx[2:0] configuration bits (see
the Channel Sequencer Details section).
Bit 5 Bit 4 Function
0 0 Disable sequencer (default)
0 1 Update configuration during basic sequence
1 0 Initialize advanced sequencer
1 1 Initialize basic sequencer
3 TEMPB
Temperature sensor enable control (see the Channel Sequencer Details section).
0 = internal temperature sensor enabled.
1 = internal temperature sensor disabled (default).
2 REFEN Internal reference selection (see the Pin Configuration and Function Descriptions and Voltage Reference
Input/Output sections for more information).
0 = disables the internal reference. The internal reference buffer is disabled by pulling REFIN to ground.
1 = enables the internal reference (default).
1 CMS Conversion mode select (see the Conversion Modes section).
0 = uses the warp mode for conversions with a time between conversion restriction.
1 = uses the normal mode for conversions (default).
0 CPHA MSB select (see the CPHA section).
0 = asserting
CS
after the end of a conversion places the MSB on SDO, and the first SCK falling edge places (MSB − 1) on SDO.
1 = asserting
CS
after the end of a conversion places the MSB on SDO, and the first SCK falling edge repeats MSB on SDO
(default).
CHANNEL SEQUENCER DETAILS
The ADAS3022 includes a channel sequencer, which is useful for
scanning channels in a sequential order. Channels are scanned
individually with reference to COM or as pairs and can also
include the auxiliary channel pair and/or the internal temperature
sensor measurement. After the last programmed measurement
is sampled, the ADAS3022 sequencer is reset to the first channel
(IN0) or channel pair (IN0/IN1) and repeats the sequence until
the sequencer is disabled or an asynchronous RESET or PD occurs.
When the channel sequencer is enabled, for all differential
pairs, the positive terminals are the even channels (IN0, IN2,
IN4, and IN6), and the negative terminals are, conversely, the
odd channels (IN1, IN3, IN5, and IN7). When the channel
sequencer is disabled, the user can assign either positive or
negative terminals to even or odd channels for all differential
pairs, depending on the INx[14:12] settings. For example, if
INx[14:12] = 001 when using the IN0/IN1 pair, IN1 is the
positive input and IN0 is the negative input.
Each sequence loop always starts with IN0 or IN0/IN1 and
terminates with either the last channel/channel pair set in the
INx bits, the temperature sensor, or the auxiliary input channel,
depending on the configuration word. Table 12 provides a quick
reference for how the device responds to the programmed configu-
ration. For the first case, the channel sequencer scans Channel IN0
through Channel IN3 in a repeated fashion. Note that the last
conversion is corrupted when exiting the sequencer.
Table 12. Typical Channel Sequencer Example
INx[14:12] COM MUX TEMPB End of Sequence
011 1 1 1 IN3 (to COM)
111 1 1 1 IN7 (to COM)
11x 0 1 1 IN6 to IN7
111
1
1
0
TEMPB
111 1 0 1 AUX
111 1 0 0 AUX
INx and COM Inputs (MUX = 1, TEMPB = 1)
To use individual INx channels with reference to COM or pairs
of INx channels in a sequence without converting the AUX or
temperature sensor channels, the MUX and TEMPB bits must
be set to 1. The last channel to be converted in the sequence is
specified by the channel set in the INx bits. After the last channel is
scanned, the next conversion starts over at IN0 or IN0/IN1. For
paired channels, the channels are paired depending on the last
channel set in INx. Note that the channels are always paired
with the positive input on the even channels (IN0, IN2, IN4,
IN6) and the negative input on the odd channels (IN1, IN3, IN5,
IN7). Therefore, setting INx to 110 or 111 scans all pairs with
the positive inputs dedicated to IN0, IN2, IN4, and IN6. For
example, to scan four single channels, set INx to 011, COM to 1,
and MUX to 1, which results in a sequence order of IN0, IN1,
IN2, IN3, IN0, IN1, IN2, and IN3.