CS43L21 datasheet(22/63 Pages) CIRRUS

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DS723A1

CS43L21

4. APPLICATIONS

4.1

Overview

4.1.1

Architecture

The CS43L21 is a highly integrated, low power, 24-bit audio D/A comprised of stereo digital-to-analog

converters (DAC) designed using multi-bit delta-sigma techniques. The DAC operates at an oversampling

ratio of 128Fs. The D/A operates in one of four sample rate speed modes: Quarter, Half, Single and Dou-

ble. It accepts and is capable of generating serial port clocks (SCLK, LRCK) derived from an input Master

Clock (MCLK).

4.1.2

Line & Headphone Outputs

The analog output portion of the D/A includes a headphone amplifier capable of driving headphone and

line-level loads. An on-chip charge pump creates a negative headphone supply allowing a full-scale out-

put swing centered around ground. This eliminates the need for large DC-Blocking capacitors and allows

the amplifier to deliver more power to headphone loads at lower supply voltages. Eight gain settings for

the headphone amplifier are available.

4.1.3

Signal Processing Engine

A signal processing engine is available to process serial input D/A data before output to the DAC. The

D/A data has independent volume controls and mixing functions such as mono mixes and left/right chan-

nel swaps. A Tone Control provides bass and treble at four selectable corner frequencies. An automatic

level control provides limiting capabilities at programmable attack and release rates, maximum thresholds

and soft ramping. A 15/50

µs de-emphasis filter is also available at a 44.1 kHz sample rate.

4.1.4

Beep Generator

A beep may be generated internally at select frequencies across approximately two octave major scales

and configured to occur continuously, periodically or at single time intervals controlled by the user. Volume

may be controlled independently.

4.1.5

Device Control (Hardware or Software Mode)

In Software Mode, all functions and features may be controlled via a two-wire I²C or three-wire SPI control

port interface. In Hardware Mode, a limited feature set may be controlled via stand-alone control pins.

4.1.6

Power Management

Two Software Mode control registers provide independent power-down control of the DAC, allowing op-

eration in select applications with minimal power consumption.

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