CS4294 datasheet(36/42 Pages) CIRRUS

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CS4294

DS326PP4

AUX_L and AUX_R - Analog Auxiliary Source, Inputs

These inputs form a stereo input pair to the CS4294. The maximum allowable input is 1 VRMS

(sinusoidal). These inputs are internally biased at the Vrefout voltage reference. AC coupling to

external circuitry is required. If these inputs are not used, they should both be connected to the

Vrefout pin or both AC coupled, with separate AC coupling caps, to analog ground.

LINE_OUT_L and LINE_OUT_R - Analog Line Level Outputs

These signals are analog outputs from the stereo output mixer. The full scale output voltage for

output is nominally 1 VRMS and is internally biased at the Vrefout voltage reference. It is

required to either AC couple these pins to external circuitry or DC couple them to a buffer op-

amp biased at the Vrefout voltage. These pins need a 680 pF to 1000 pF NPO capacitor

attached to analog ground.

ALT_LINE_OUT_L and ALT_LINE_OUT_R - Analog Alternate Line Level Outputs

These signals are analog outputs from the stereo output mixer. The full scale output voltage for

each output is nominally 1 VRMS and is internally biased at the Vrefout voltage reference. It is

required to either AC couple these pins to external circuitry or DC couple them to a buffer op-

amp biased at the Vrefout voltage. These pins need a 680 pF to 1000 pF NPO capacitor

attached to analog ground.

8.3

Filter and Reference Pins

REFFLT - Internal Reference Voltage, Input

This is the voltage reference used internal to the part. A 0.1

µF and a 1 µF (must not be larger

than 1

µF) capacitor with short, wide traces must be connected to this pin. No other

connections should be made to this pin.

Vrefout - Voltage Reference, Output

All analog inputs and outputs are centered around Vrefout which is nominally 2.2 Volts. This

pin may be used to level shift external circuitry, however any external loading should be

buffered.

AFLT1 - Left Channel Antialiasing Filter Input

This pin needs a 1000 pF NPO capacitor attached to analog ground.

AFLT2 - Right Channel Antialiasing Filter Input

This pin needs a 1000 pF NPO capacitor attached to analog ground.

FLTI - Enhanced Stereo Filter Input

A 1000 pF capacitor must be attached between this pin and FLTO if the Stereo Enhancement

function is used.

FLTO - Enhanced Stereo Filter Output

A 1000 pF capacitor must be attached between this pin and FLTI if the Stereo Enhancement

function is used.

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