18.104.22.168 Multiplexer Configurations
The ADS816x supports single-ended and pseudo-differential analog input signals. The flexible analog input channel configuration supports interfacing various types of sensors. Figure 31 shows how the analog inputs can be configured.
Figure 31. Analog Input Configurations
The analog inputs can be configured as:
- 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 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 can be configured as pairs and some inputs are configured as individual channels. Table 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 1. Channel Configuration Options(1)(2)
(1) Channel pairs can be 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.
The COM_CFG register sets the input voltage range of the AIN-COM pin. AIN-COM pin must be connected 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.