AD1885JST Analog Devices Inc, AD1885JST Datasheet - Page 23

• Manufacturer Part Number: AD1885JST
• Description: IC AUDIO CODEC AC'97 48-LQFP
• Manufacturer: Analog Devices Inc
• Series: SoundMAX®r
• Type: Audio Codec '97r

Specifications of AD1885JST

• Rohs Status: RoHS non-compliant
• Data Interface: Serial
• Resolution (bits): 16 b
• Number Of Adcs / Dacs: 2 / 2
• Sigma Delta: Yes
• Dynamic Range, Adcs / Dacs (db) Typ: 87 / 90
• Voltage - Supply, Analog: 4.75 V ~ 5.25 V
• Voltage - Supply, Digital: 3.15 V ~ 3.45 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP

JACK SENSE OPERATION
The AD1885 features two Jack Sense pins (JS0 and JS1) that can be used to automatically mute the LINE_OUT and/or MONO_OUT
audio outputs. When the Jack Sense pins are connected to the output jacks, the AD1885 can sense whether an audio plug has been
inserted into a particular output jack and automatically mute the other unnecessary audio outputs.
The JS1 pin should normally be connected to the HP_OUT jack to automatically mute the MONO_OUT and LINE_OUT audio
signals, while the JS0 pin should normally be connected to the LINE_OUT jack to automatically mute the MONO_OUT signal. It is
also possible to set the D15 bit in the Jack Sense Index Register (72h), which causes JS1 to only mute the LINE_OUT signal. This
option may be desirable in certain audio configurations. Table I summarizes the Jack Sense operation.
HP_OUT Plug
(JS1)
OUT
OUT
IN
IN
NOTE: PLUG IN = JACK SENSE HIGH, PLUG OUT = JACK SENSE LOW.
The Jack Sense inputs are active high and their functionality is enabled by default on CODEC power-up. If necessary, the Jack Sense
inputs can be individually disabled by writing to the D8 and D9 bits on the CODEC Jack Sense Index Register (72h).
The Jack Sense pins contain active internal pull-ups. If the Jack Sense inputs are not being used, they should be pulled down to
digital ground using 10 kΩ resistors. This prevents LINE_OUT and MONO_OUT from becoming muted while the Jack Senses are
enabled.
CONNECTING THE JACK SENSES TO THE OUTPUT JACKS
Headphone Jack
The diagram on Figure 10 shows the preferred method to connect the JS1 Jack Sense line to the HP_OUT jack. This scheme requires
a stereo jack with a normally closed and isolated single switch. The switch holds the Jack Sense line low (grounded) until an audio
plug is inserted, causing the switch to open and the Jack Sense line to go high due to the CODEC internal pull-up. The R2 and R3
resistors keep the electrolytic output caps properly polarized while the HP_OUT jack is not used.
Alternatively, when an audio output jack containing an isolated switch is not available, the circuit shown on Figure 11 can be used.
While the audio plug is out, this circuit keeps the Jack Sense line state low, by the pull-down affect of R2 (with no audio present) or
by tracking the lower peaks of the HP_OUT audio signal. Once an audio plug is inserted and the jack switch opens, the Jack Sense
line switches to a high state due to the CODEC internal pull-up, which quickly charges C1 to DVDD.
The R2 and R3 resistors also keep the electrolytic output caps properly polarized while the HP_OUT jack is not used.
FROM CODEC HP_OUT_R (PIN 41)
FROM CODEC HP_OUT_L (PIN 39)
TO CODEC JS1 (PIN 48)
LINE_OUT Plug
(JS0)
OUT
IN
OUT
IN
NOTE: LOCATE R1 CLOSE TO CODEC.
Table I. Jack Sense Operation Table
+
+
Audio Output States
(REG 72h, D15 = 0)
HP_OUT = ON
LINE_OUT = ON
MONO_OUT = ON
HP_OUT = ON
LINE_OUT = ON
MONO_OUT = MUTE
HP_OUT = ON
LINE_OUT = MUTE
MONO_OUT = MUTE
HP_OUT = ON
LINE_OUT = MUTE
MONO_OUT = MUTE
JACK SENSE LINE
OPTIONAL EMC
C1
470pF
COMPONENTS
C4
470pF
L1 600Z
L2 600Z
5
4
3
2
1
HEADPHONE OUT
NC SWITCH
ISOLATED
Audio Output States
(REG 72h, D15 = 1)
HP_OUT = ON
LINE_OUT = ON
MONO_OUT = ON
HP_OUT = ON
LINE_OUT = ON
MONO_OUT = MUTE
HP_OUT = ON
LINE_OUT = MUTE
MONO_OUT = ON
HP_OUT = ON
LINE_OUT = MUTE
MONO_OUT = MUTE
AD1885