The ADS816x supports
single-ended and pseudo-differential analog input signals. The flexible analog input
channel configuration supports interfacing various types of sensors. Figure 6-2 shows how
different configurations for the analog inputs.
The analog inputs
configurations are:
- Configuration 1: Eight-channel MUX with the AIN_CFG register set to 00h. The AIN-COM input range is decided by
the COM_CFG register.
- Single-ended inputs with the AIN-COM input set to GND
(set the COM_CFG register to 00h).
- Pseudo-differential inputs with the AIN-COM input set
to VREF / 2 (set the COM_CFG register to 01h).
- Configuration 2: Four-channel MUX.
- As shown in Table 6-1,
the AIN_CFG register selects the analog input range of individual
pairs.
- Configuration 3: Single-ended and pseudo-differential inputs.
- Among the eight analog inputs of the MUX, some inputs are configured as pairs
and some inputs are configured as individual channels. Table 6-1
lists options for channel configuration.
- For channels configured as pairs, the AIN_CFG register selects the single-ended or pseudo-differential configuration for individual pairs.
- For individual channels, the COM_CFG register decides the single-ended or pseudo-differential configuration.
Table 6-1 Channel Configuration
Options
SERIAL NUMBER |
TOTAL CHANNELS |
INPUT PAIRS(1)(2) |
INDIVIDUAL CHANNELS |
1 |
8 |
0 |
8 |
2 |
7 |
1 |
6 |
3 |
6 |
2 |
4 |
4 |
5 |
3 |
2 |
5 |
4 |
4 |
0 |
(1) Channel pairs are formed as [AIN0 - AIN1], [AIN2 - AIN3], [AIN4 - AIN5], and
[AIN6 - AIN7].
(2) When channels are configured as pairs, AIN0, AIN2, AIN4, and AIN6 are positive inputs.
Note: The COM_CFG register sets the input voltage range
of the AIN-COM pin. Connect the AIN-COM pin to GND (set the COM_CFG register to
0b) or REFby2 (set the COM_CFG register to 1b) externally. When using the MUX in
a four-channel configuration, the COM_CFG register has no effect; connect the
AIN-COM pin to GND to avoid noise coupling.