Preliminary

Avance Logic, Inc.

ALC202

- 20 -

Rev0.62

http://www.realtek.com.tw

5.8 Jack-Detect Function

JD (Jack-Detect) is an internal pull high input pin used to decide whether LINE-OUT should be auto

muted or not. If JDE (Jack Detect Enable) is set and ALC202 detects the JD is floating or pull high

(JDS=1), ALC202 will disable the analog output of LINE-OUT even the MX02 is not muted.

Fig5.8-1 shows the jack detect example to implement this function. If no audio plug is inserted in

HP-OUT jack, JD is detected as low, LINE output normally. If audio plug is inserted, ALC202 disable

LINE output, still output to HP-OUT and MONO-OUT. It’s useful to some PC application especially

in notebook environment.

If headphone output jack is not implemented and HP-OUT kept as floating, once JDE is enable, LINE

output will be muted unless JD is pull low by a 10K ohm resistor (Fig5.8-2). To conquer this

disadvantage, the Jack-Detect mute LINE-OUT function is disable after power up (default JDE is 0),

that make ALC202 compatible with others AC’97. So it is software’s responsibility to enable this

function if headphone jack detection is implemented.

Fig5.8-1 Jack detect connection example

Fig5.8-2 JD is pull low by a 10K ohm resistor

JD

HP-OUT-R

HP-OUT-L

4.7K

HP-OUT

5

4

3

2

1

+

3.3u

4.7K

4.7K

+100uf

+100uf

HP-OUT-R

HP-OUT-L

JD

10K

If HP-OUT jack is not implemented,

JD must be pulled low to prevent JDS is set