AD1881AJSTZ Analog Devices Inc, AD1881AJSTZ Datasheet - Page 22

• Manufacturer Part Number: AD1881AJSTZ
• Description: IC AUDIO CODEC AC'97 48-LQFP
• Manufacturer: Analog Devices Inc
• Series: SoundMAX®r
• Type: Audio Codec '97r

Specifications of AD1881AJSTZ

• Data Interface: Serial
• Resolution (bits): 16 b
• Number Of Adcs / Dacs: 2 / 2
• Sigma Delta: Yes
• S/n Ratio, Adcs / Dacs (db) Typ: 90 / 90
• Dynamic Range, Adcs / Dacs (db) Typ: 87 / 90
• Voltage - Supply, Analog: 4.75 V ~ 5.25 V
• Voltage - Supply, Digital: 3 V ~ 3.6 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Single Supply Voltage (typ): 3.3/5V
• Single Supply Voltage (min): 3/4.75V
• Single Supply Voltage (max): 3.6/5.25V
• Package Type: LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD1881A
CD-ROM CONNECTIONS
The CD-ROM audio output level should be investigated; typical drives generate 2 V rms output and require a voltage divider for
compatibility with the Codec input (1 V rms range). The recommended circuit is basically a group of divide-by-two voltage dividers
as shown on Figure 10.
The CD_GND_REF pin is used to cancel differential ground noise from the CD-ROM. For optimum noise cancellation, this section
of the divider should have approximately half the impedance of the right and left channel section dividers.
LINE_IN, AUX AND VIDEO INPUT CONNECTIONS
Most of these audio sources also generate 2 V rms audio level and require a –6 dB input voltage divider to be compatible with the
Codec inputs. Figure 11 shows the recommended application circuit. For applications requiring EMC compliance, the EMC compo-
nents should be configured and selected to provide adequate RF immunity and emissions control.
MICROPHONE CONNECTIONS
The AD1881A contains an internal microphone preamp with 20 dB gain, in most cases a direct microphone connection as shown in
Figure 12 is adequate. If the microphone level is too low, an external preamp can be added as shown in Figure 13. In either case the
microphone bias can be derived from the Codec’s internal reference (V
V
To meet the PC99 1.0A requirements, the MIC signal should be placed on the microphone jack tip and the bias on the ring. This
configuration supports electret microphones with three conductor plugs, as well as dynamic microphones with two conductor plugs
(ring and sleeve shorted together).
Additional filtering may be required to limit the microphone response to the audio band of interest.
REFOUT
signal can also provide the mid-point bias for the amplifier.
CD ROM AUDIO
LINE/AUX/VIDEO
HEADER FOR
J1
INPUT
(LGGR)
1
2
3
4
5
COMPONENTS
L2 600Z
L1 600Z
1
2
3
4
470pF
470pF
EMC
C1
C2
VOLTAGE
DIVIDER
4.7k
2.7k
4.7k
R1
R3
R5
4.7k
4.7k
R1
R3
VOLTAGE
DIVIDER
R2
4.7k
R4
2.7k
R6
4.7k
R2
4.7k
R4
4.7k
REFOUT
AC-COUPLING
0.33 F
0.33 F
0.33 F
0.33 F
0.33 F
C1
C2
C3
C3
C4
) using a 2.2 kΩ resistor. For the preamp circuit, the
+
+
+
+
+
TO CODEC
RIGHT CHANNEL
INPUT
TO CODEC
LEFT CHANNEL
INPUT
TO CODEC
CD_GND_REF
INPUT
TO CODEC
CD_R INPUT
TO CODEC
CD_L INPUT