CS43L21 datasheet(27/63 Pages) CIRRUS

27 / 63 page

DS723A1

CS43L21

4.3.7

Line-Level Outputs and Filtering

The CODEC contains on-chip buffer amplifiers capable of producing line level single-ended outputs on

AOUTA and AOUTB. These amplifiers are ground centered and do not have any DC offset. A load stabi-

lizer circuit, shown in the “Typical Connection Diagram (Software Mode)” on page 9 and the “Typical Con-

nection Diagram (Hardware Mode)” on page 10, is required on the analog outputs. This allows the DAC

amplifiers to drive line or headphone outputs.

Also shown in the Typical Connection diagrams is the recommended passive output filter to support high-

er impedances such as those found on the inputs to operational amplifiers. “Rext”, shown in the typical

connection diagrams, is the input impedance of the receiving device.

The invert and digital gain controls may be used to provide phase and/or amplitude compensation for an

external filter.

The delta-sigma conversion process produces high frequency noise beyond the audio passband, most of

which is removed by the on-chip analog filters. The remaining out-of-band noise can be attenuated using

an off-chip low pass filter.

Software

Controls:

“DAC Output Control (Address 08h)” on page 41, “AOUTx Volume Control: AOUTA (Address 16h)

& AOUTB (Address 17h)” on page 49.

MAX[2:0]

Output

(after Limiter)

Input

RRATE[5:0]

ARATE[5:0]

Volume

Limiter

CUSH[2:0]

ATTACK/RELEASE SOUND

CUSHION

MAX[2:0]

AOUTx_VOL[7:0] volume

control should NOT be

adjusted manually when

Limiter is enabled.

Figure 11. Peak Detect & Limiter

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