AD1983

Rev. 0 | Page 14 of 16

JACK PRESENCE DETECTION

The AD1983 uses one jack sense line for presence detection on

up to four external jacks. This enables software to determine if

there is a device plugged into a jack; then, the AD1983 sensing

engine can determine what type of device it is. Jack presence is

detected using a resistor tree arrangement outlined in the HD

Audio specification. Up to four jacks can be sensed on a single

sense line by using a different value resistor for each between

open, isolated switches to use this method of jack presence

detection.

For proper operation there must be a 2.67 kΩ 1% resistor

R1 and C1 should be installed; R2 should not be installed

(see Figure 3).

The specific resistor values for each jack are shown in Table 13.

To ensure accurate detection, use 1% tolerance resistors for all

jack presence circuitry.

Table 13. Jack Sense Mapping

SENSE_A

Resistor (1%)

Name

Port

Node ID

(Hex)

5.1 kΩ

Line Out

D

05

10.0 kΩ

Line In

C

09

20.0 kΩ

Microphone

B

08

39.2 kΩ

Headphone Out

A

06

An alternate method reduces the current for sensing by

connecting a single 2.67 kΩ 1% resistor between the SENSE_A

and SENSE_SRC pins. For this configuration R1 and C1 are not

installed; however, R2 is installed (see Figure 3).

It is recommended that designers place circuitry for both

sensing methods and only install one of the two options.

SENSE_A/SRC_B

TO JACKS FOR

PORT A THROUGH PORT D

AD1983

C1

1µF

SENSE_SRC

22, 26

21

17, 29

9

R1

2.67kΩ, 1%, 1/8W

R2 (DNE)

2.67kΩ, 1%, 1/8W

Figure 3. Jack Presence Detection