Cirrus Logic CS43L22 - Manual (Page 20)

20 DS792F2
CS43L22
Confidential Draft
3/4/10
4. APPLICATIONS
4.1 Overview
4.1.1 Basic Architecture
The CS43L22 is a highly integrated, low power, 24-bit audio DAC comprised of a Digital Signal Processing
Engine, headphone amplifiers, a digital PWM modulator and two full-bridge power back-ends. Other fea-
tures include battery level monitoring and compensation and temperature monitoring. The DAC is de-
signed using multi-bit delta-sigma techniques and operates at an oversampling ratio of 128Fs, where Fs
is equal to the system sample rate.
The PWM modulator operates at a fixed frequency of 384 kHz. The power MOSFETs are configured for
either stereo full-bridge or mono parallel full bridge output. The DAC operates in one of four sample rate
speed modes: Quarter, Half, Single and Double. It accepts and is capable of generating serial port clocks
(SCLK, LRCK) derived from an input Master Clock (MCLK).
4.1.2 Line Inputs
4 pairs of stereo analog inputs are provided for applications that require analog passthrough directly to
the HP/Line amplifiers. This analog input portion allows selection from and configuration of multiple com-
binations of these stereo sources.
4.1.3 Line & Headphone Outputs
The analog output portion of the CS43L22 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
output swing centered around ground. This eliminates the need for large DC-Blocking capacitors and al-
lows the amplifier to deliver more power to headphone loads at lower supply voltages.
4.1.4 Speaker Driver Outputs
The Class D power amplifiers drive 8 Ω (stereo) and 4 Ω (mono) speakers directly, without the need for
an external filter. The power MOSFETS are powered directly from a battery eliminating the efficiency loss
associated with an external regulator. Battery level monitoring and compensation maintains a steady out-
put as battery levels fall. A temperature monitor continually measures the die temperature and registers
when predefined thresholds are exceeded.
NOTE: The CS43L22 should only be used in captive speaker
systems where the outputs are permanently tied to the speaker terminals.
4.1.5 Fixed Function DSP Engine
The fixed-function digital signal processing engine processes the PCM serial input data. Independent vol-
ume control, left/right channel swaps, mono mixes, tone control and limiting functions also comprise the
DSP engine.
4.1.6 Beep Generator
The beep generator delivers tones at select frequencies across approximately two octave major scales.
With independent volume control, beeps may be configured to occur continuously, periodically, or at sin-
gle time intervals.
4.1.7 Power Management
Two control registers provide independent power-down control of the DAC, Headphone and Speaker out-
put blocks in the CS43L22 allowing operation in select applications with minimal power consumption.