CS4237B Datasheet, PDF (107/114 Pages) Cirrus Logic – CrystalClear Advanced Audio System with 3D Sound

CS4237B
VREF - Voltage Reference, Output
All analog inputs and outputs are centered around VREF which is nominally 2.1 Volts. This
pin may be used to level shift external circuitry, although any AC loads should be buffered.
REFFLT - Reference Filter, Input
Voltage reference used internal to the part. A 0.1 µF and a 1 µF (must not be bigger than 1 µF)
capacitor with short fat traces must be connected to this pin. No other connections should be
made to this pin.
LFILT - Left Channel Antialias Filter Input
This pin needs a 1000 pF NPO capacitor attached and tied to analog ground.
RFILT - Right Channel Antialias Filter Input
This pin needs a 1000 pF NPO capacitor attached and tied to analog ground.
TEST - Test
This pin must be tied to ground for proper operation.
Power Supplies
VA - Analog Supply Voltage
Supply to the analog section of the codec.
AGND - Analog Ground
Ground reference to the analog section of the codec. This pin should be placed on an analog
ground pin separate from other chip grounds.
VD1 - Digital Supply Voltage
Digital supply for the parallel data bus section of the codec.
DGND1 - Digital Ground
Digital ground reference for the parallel data bus section of the part. These pins are isolated
from the other grounds and should be connected to the digital ground section of the board (see
Figure 33).
VDF1, VDF2, VDF3, VDF4 - Digital Filtered Supply Voltage
Digital supply for the internal digital section of the codec (except for the parallel data bus).
These pins should be filtered, using a ferrite bead, from VD1.
SGND1, SGND2, SGND3, SGND4 - Substrate Ground
Substrate ground reference for the codec . These pins are connected to the substrate of the die.
Optimum layout is achieved by placing SGND1/2/3/4 on the digital ground plane with the
DGND pin as shown in Figure 33.
DS213PP4
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