CS4811 Cirrus Logic, CS4811 Datasheet - Page 12

• Manufacturer Part Number: CS4811
• Description: Fixed Function Multi-Effects Audio Processor
• Manufacturer: Cirrus Logic

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3. FUNCTIONAL DESCRIPTION
3.1
The CS4811 is a complete audio subsystem on a
chip, integrating a proprietary 24-bit audio process-
ing engine with large on chip RAM memories and
a single channel 24-bit audio codec.
The delta-sigma ADC includes linear phase digital
anti-aliasing filters and only requires a single-pole
external passive filter.
The sigma-delta DAC includes a switched-capaci-
tor anti-image filter and requires an external 2nd or
3rd order active filter that can be easily integrated
into the output differential-to-single-ended con-
verter circuit.
The serial control port is designed to accommodate
I
with an external non-volatile memory.
3.2
3.2.1
AIN+ and AIN- are the differential line level ana-
log inputs (See Figure 3). These pins are internally
biased to the CMOUT voltage of 2.3 V. A DC
blocking capacitor placed in series with the input
12
2
C
®
or SPI interfaces for stand-alone operation
Overview
Analog Inputs
Line Level Inputs
(2 Vrms max)
CMOUT
input signal
CS4811
from
+
-
10 F
+
Figure 6. Optional Line Input Buffer
10 k
Buffered
CMOUT
-
+
4.7 k
+
10 f
10 k
0.1 F
pins allows signals centered around 0 V to be input
to the CS4811. Figure 3 shows operation with a
single-ended input source. This source may be sup-
plied to either the positive or negative input as long
as the unused input is connected to ground through
capacitors as shown. When operated with single-
ended inputs, distortion will increase at input levels
higher than -1 dB Full Scale. If better performance
is required, a single-ended-to-differential convert-
er, shown in Figure 6, may be used. This circuit
provides unity gain, DC blocking on the input and
anti-alias filtering.
The OVL output pin asserts when the analog input
is out-of-range.
3.2.2
In DC coupled systems, a small DC offset may ex-
ist between the input circuitry and the A/D con-
verters. The CS4811 includes a high pass filter
after the decimator to remove these DC compo-
nents. The high pass filter response, given in High
Pass Filter Characteristics, scales linearly with
sample rate. Thus, the -3 dB frequency at a
44.1 kHz sample rate will be equal to 44.1/48 times
that at a sample rate of 48 kHz.
+
-
10 k
GND
+5 V
Digital High Pass Filter
150
150
2.2 nf
AIN -
AIN +
CS4811
DS486PP2