CS4294SLASHCS4298 datasheet(14/81 Pages) CIRRUS

14 / 81 page

CS4205

DS489PP4

2.2

Control Registers

The CS4205 contains a set of AC ’97 compliant

control registers, and a set of Cirrus Logic defined

control registers. These registers control the basic

functions and features of the CS4205. Read access-

es of the control registers by the AC ’97 controller

are accomplished with the requested register index

in Slot 1 of a SDATA_OUT frame. The following

SDATA_IN frame will contain the read data in Slot

2. Write operations are similar, with the register in-

dex in Slot 1 and the write data in Slot 2 of a

SDATA_OUT frame. The function of each input

and output frame is detailed in Section 4, AC-Link

Frame Definition. Individual register descriptions

are found in Section 5, Register Interface.

2.3

Sample Rate Converters

The sample rate converters (SRC) provide high ac-

curacy digital filters supporting sample frequencies

other than 48 kHz to be captured from the CS4205

or played from the controller. AC ’97 requires sup-

port for two audio rates (44.1 and 48 kHz) and four

modem rates (8, 9.6, 13.714, and 16 kHz). In addi-

tion, the Intel® I/O Controller Hub (ICHx) specifi-

cation [9] requires support for five more audio rates

(8, 11.025, 16, 22.05, and 32 kHz) and specifies

two optional modem rates (24, 48kHz). The

CS4205 supports all these rates, as shown in

Table 12 on page 38.

2.4

Mixers

The CS4205 input and output mixers are illustrated

in Figure 8. The stereo input mixer sums together

the analog inputs to the CS4205 according to the

settings in the volume control registers. The stereo

output mixer sums the output of the stereo input

mixer with the PC_BEEP and PHONE signals. The

stereo output mix is then sent to the LINE_OUT

pins of the CS4205. The mono output mixer gener-

ates a monophonic sum of the left and right audio

channels from the stereo input mixer. The mono

output mix is then sent to the MONO_OUT pin on

the CS4205.

2.5

Input Mux

The input multiplexer controls which analog input

is sent to the ADCs. The output of the input mux is

converted to stereo 18-bit digital PCM data and

transmitted to the controller by means of the

AC-link SDATA_IN signal.

2.6

Volume Control

The CS4205 volume registers control analog input

levels to the input mixer and analog output levels,

including the master volume level. The PC_BEEP

volume control uses 3 dB steps with a range of 0 dB

to -45 dB attenuation. All other analog volume con-

trols use 1.5 dB steps. The analog inputs have a

mixing range of +12 dB signal gain to -34.5 dB sig-

nal attenuation. The analog output volume controls

have a range of 0 dB to -46.5 dB attenuation for

LINE_OUT and MONO_OUT.

2.7

Dedicated Mic Record Path

The CS4205 includes a dedicated microphone

ADC that supports advanced functions such as

speech recognition and internet telephony. The

dedicated ADC allows recording of a microphone

input independent of the input mux settings. This

enables simultaneous capture of microphone and

independent stereo sources.

CS4294/CS4298 数据表(PDF) 14 Page - Cirrus Logic

CS4294/CS4298 数据表(HTML) 14 Page - Cirrus Logic

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81

数据表下载