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AD7143

Rev. 0 | Page 13 of 56

CAPACITANCE SENSOR INPUT CONFIGURATION

Each input connection from the external capacitance sensors to

the AD7143 converter can be uniquely configured by using the

registers in Table 38 and Table 39. These registers are used to

configure input pin connection setups, sensor offsets, sensor

sensitivities, and sensor limits for each stage. Each sensor can be

individually optimized. For example, a button sensor connected

to STAGE0 can have a different sensitivity and offset values

than a button with a different function that is connected to a

different stage.

CIN INPUT MULTIPLEXER SETUP

The CIN_CONNECTION_SETUP registers in Table 38 list the

available options for connecting the sensor input pin to the CDC.

The AD7143 has an on-chip multiplexer to route the input

signals from each pin to the input of the converter. Each input

pin can be tied to either the negative or the positive input of the

CDC or can be left floating. Each input can also be internally

connected to the CSHIELD signal to help prevent cross coupling. If

an input is not used, always connect it to CSHIELD.

Connecting a CINx input pin to the positive CDC input results

in a decrease in CDC output code when the corresponding

sensor is activated. Connecting a CINx input pin to the negative

CDC input results in an increase in CDC output code when the

corresponding sensor is activated.

Two bits in each sequencer stage register control the mux

setting for the input pin.

CIN CONNECTION SETUP BITS

CIN SETTING

CINx FLOATING

CINx CONNECTED TO

NEGATIVE CDC INPUT

CINx CONNECTED TO

POSITIVE CDC INPUT

CINx CONNECTED TO

INTERNAL BIAS

CIN0

CIN1

CIN2

CIN3

CIN4

CIN5

CIN6

CIN7

–

CDC

Figure 20. Input Mux Configuration Options

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