The PCM1809 device is intended to be driven with differential line or microphone inputs. Each of the inputs has a 1µF AC coupling film capacitor. Coupled with the 10kΩ input impedance of PCM1809, this sets the high pass filter cutoff frequency at approximately 16Hz. This can be adjusted by replacing the input AC coupling capacitors on the EVM if necessary. PCM1809 is optimized to support AC/DC coupling in both single-ended or differential input configurations. Figure 3-2 shows the architecture of the inputs to the evaluation module. The EVM supports a differential full scale input range of 2 VRMS with an AVDD of 3.3V.

Figure 2-2 PCM1809 Input Architecture