ZHCSCB3D March 2014 – March 2018 PCM1860 , PCM1861 , PCM1862 , PCM1863 , PCM1864 , PCM1865
PRODUCTION DATA.
The PCM186x has a flexible front end that accepts either differential or single-ended inputs. The device supports up to 2.1 VRMS in single-ended mode, and up to 4.2 VRMS in differential mode.
The MIX and MUX circuit before the PGA allows the analog inputs to be mixed and multiplexed in both single-ended and differential modes. Mixing functionality is available in software-controlled devices only. No individual gain controls are available before the PGA. A high-level diagram of the front-end circuitry is shown in Figure 27.
DC blocking capacitors are required on the analog inputs to make sure that correct dc bias conditions are established. Because the value of the output short-circuit protection resistor in the source product is typically unknown, issues such as gain error and dc shift may occur if dc blocking capacitors are not used.
For systems where external amplifiers are used before the PCM186x, dc blocking capacitors are still recommended because the input pins are designed to bias to AVDD / 2. The common mode voltage range is still limited to the maximum input voltage of the device.
Do not connect unused analog input pins.