The FDC1004-Q1 can be used for interfacing to a single-ended capacitive sensor. In this configuration, connect the sensor to the input CINn (n = 1..4) pins of the FDC1004-Q1 and GND. The capacitance-to-digital convertor (without using the CAPDAC, CAPDAC= 0pF) measures the positive (or the negative) input capacitance in the range of 0pF to 15pF. The CAPDAC can be used for programmable shifting of the input range. In this case it is possible to measure input capacitance in the range of 0pF to ±15pF which are on top of an offset capacitance up to 100pF. In single ended measurements with CAPDAC disabled SHLD1 is internally shorted to SHLD2 (see Figure 6-1); if CAPDAC is enabled SHLD2 is floating (see Figure 6-2). The single ended mode is enabled when the CHB register of the Measurements configuration registers (see Table 6-4) are set to b100 or b111.

Figure 6-1 Single-Ended Configuration with CAPDAC Disabled

Figure 6-2 Single-Ended Configuration with CAPDAC Enabled