SBAS495D June 2010 – August 2021 PCM9211
PRODUCTION DATA
The PCM9211 has four power-supply pins and four ground pins. All ground pins (AGND, AGNDAD, DGND, and GNDRX) must be connected as closely as possible to the PCM9211. The PCM9211 DVDD and DGND pins are power-supply pins that support all the onboard digital circuitry for the PCM9211. DVDD should be connected to a 3.3-V supply. DVDD drives the internal power-on reset circuit, making it a startup requirement.
VCC and AGND are analog power-supply power pins that support the DIR analog supply rails.
VDDAD and AGNDAD are dedicated power-supply pins for the onboard ADC. VDDAD should be connected to a 5.0-V power rail.
VDDRX is a dedicated power supply for the coaxial input amplifiers on pins RXIN0 and RXIN1. It should be connected to a 3.3-V pin. The relative GND pin for this supply is GNDRX. If the coaxial amplifiers are not used (for example, the application only uses optical inputs), then no power supply is required for the VDDRX.
If the onboard ADC is not used (such as when the application uses an external ADC) then no power supply is required for the VCCAD pin. This option means that a 5-V rail is not required when the internal ADC is not used. In such situations, VCCAD should be connected to AGND OR AGNDAD.
Because VCC (3.3 V) is an analog supply (used as part of the power supply for the DIR PLL), make sure that minimum noise and ripple are present. 0.1-μF ceramic capacitors and 10-μF electrolytic capacitors should be used to decouple each supply pin to the respective relative GND (for example, to decouple VCCAD and AGNDAD).