CS4299 datasheet(38/52 Pages) CIRRUS

38 / 52 page

CS4299

6.1.5

Phone Input

One application of the PHONE input is to interface

to the output of a modem analog front end (AFE)

device so that modem dialing signals and protocol

negotiations may be monitored through the audio

system. Figure 16 shows a design for a modem

connection where the output is fed from the

CS4299 MONO_OUT pin through a divider. The

divider ratio shown does not attenuate the signal,

providing an output voltage of 1 VRMS. If a lower

output voltage is desired, the resistors can be re-

placed with appropriate values, as long as the total

load on the output is kept greater than 10 k

Ω. The

PHONE input is divided by 6 dB to accommodate

a line-level source of 2 VRMS.

6.2

Analog Outputs

The analog line-level output section provides two

stereo

outputs

and

mono

output.

The

LINE_OUT_L/R,

ALT_LINE_OUT_L/R,

and

MONO_OUT pins require 680 pF to 1000 pF NPO

capacitors between the corresponding pin and ana-

log ground. Each analog output is DC-biased up to

the Vrefout signal reference, nominally 2.3 V. This

requires the outputs be AC-coupled to external cir-

cuitry (AC load must be greater than 10 k

Ω) or DC

coupled to a buffer op-amp biased at Vrefout.

6.2.1

Stereo Outputs

See Figure 18 for a line-level stereo output refer-

ence design. See Figure 17 for a recommended

headphone stereo output reference design.

6.2.2

Mono Output

The mono output, MONO_OUT, can be either a

sum of the left and right output channels, attenuat-

ed by 6 dB to prevent clipping at full scale, or the

selected Mic signal. The mono out channel can

drive the PC internal mono speaker using an appro-

priate buffer circuit

PHONE

MONO_OUT

PHONE

MONO_OUT

6.8 k

Ω

1.0

µF

0 Ω

6.8 k

Ω

1.0

µF

47 k

Ω

AGND

1000 pF

Figure 16. Modem Connection

ALT_LINE_OUT_R

ALT_LINE_OUT_L

27 k

Ω

1000 pF

NPO

AGND

220

µF

ELEC

220

µF

ELEC

1000 pF

NPO

27 k

Ω

47 k

Ω

AGND

22 pF

NPO

39 k

Ω

22 pF

NPO

39 k

Ω

TDA1308

Vrefout

10 Ω

1/4 Watt

10 Ω

1/4 Watt

47 k

Ω

Headphone

Out

Figure 17. Alternate Line Output as Headphone Output

AGND

ALT_LINE_OUT_R

27 k

Ω

1000 pF

NPO

1000 pF

NPO

AGND

0.1 µF

Y5V

220 µF

39 k

Ω

22 pF

NPO

22 pF

NPO

TDA1308

ALT_LINE_OUT_L

VREFOUT

ELEC

1/4 WATT

Ω

HP_OUT_R

220 µF

ELEC

1/4 WATT

Ω

HP_OUT_L

47 k

Ω

AGND

1 µF

Figure 18. Stereo Output

CS4299 датащи(PDF) 38 Page - Cirrus Logic

CS4299 датащи(HTML) 38 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

датащи скачать

ссылки URL