Data Sheet

ADAS3022

Rev. A | 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.