PACAC97 Datasheet, PDF (1/4 Pages) California Micro Devices Corp – PC AUDIO RESISTOR NETWORK

CALIFORNIA MICRO DEVICES
PACAC97
PC Audio Resistor Network
Features
Applications
• Signal conditioning and gain setting resistors for
all standard audio functions
• Low noise thin film resistors ±1% match
• Better than 1% matching between channels
• Gain modification by changing resistors
externally
• Better than –90dB inter-channel and channel-to-
channel crosstalk
• Single 28-pin QSOP package
• Saves board space and reduces assembly cost
• Analog audio system for Pentium II Class personal
computers, used in conjunction with Audio Codec,
CS4297 or AD1819A.
Product Description
High quality audio systems have become standard for
most personal computers. Furthermore, the audio
functions have been migrating to the motherboard,
putting pressure on available board space. The
PACAC97 provides the components necessary for signal
conditioning of analog audio inputs for an AC97 compli-
ant Codec as well as gain setting resistors for head-
phone and microphone amplifiers. Since analog signal
levels can be as high as 2Vrms, the PACAC97 provides
6dB of attenuation (to 1Vrms) for LINE-IN, AUX, and CD
inputs. The CD line level inputs of the PACAC97 have an
additional ground signal, CD_GND, that supports the
pseudo differential amplifier present in AC97 Codecs.
This feature facilitates attenuation of common mode
ground noise typically present at the output of CD ROM
drives. Connecting the CD pins as indicated in the
application circuit provides attenuation of common mode
noise from the CD inputs, thereby producing a higher
quality CD signal. Finally, the device provides gain-
setting resistors for the headphone and microphone
amplifiers. The PACAC97 provides exceptional inter-
channel and channel-to-channel crosstalk attenuation
necessary for high quality audio.
The PACAC97 provides performance, high reliability, and
low cost through manufacturing efficiency, utilizing high
volume and low cost IC manufacturing and processes.
The process yields low noise and highly stable resistors
demanded in audio applications. In addition, the 28-pin
QSOP package is an industry standard that is easy to
handle in manufacturing and provides package reliability
SCHEMATIC CONFIGURATION
AMP1–
AMP_OUT2
AMP_OUT1
IN1
AMP2– IN2
28
27
26
25
24
23
R23
33KΩ
R23
22KΩ
R22
33KΩ
R21
22KΩ
GND
22
MIC IN MIC+
MIC_AMP_OUT
MIC–
CD_R
CD_GND
CD_L
21
20
R20
R19
4.7KΩ 33KΩ
19
18
R17
100KΩ
17
16
15
R13
6.8KΩ
R11
3.4KΩ
R9
6.8KΩ
R18
4.7KΩ
R15
510KΩ
R14
6.8 KΩ
R12
3.4KΩ
R10
6.8KΩ
R16
100KΩ
R2
6.8KΩ
R4
6.8KΩ
R5
6.8KΩ
R7
6.8KΩ
R1
6.8KΩ
R3
6.8KΩ
R6
6.8KΩ
R8
6.8KΩ
1
2
3
4
5
6
7
8
9
10
11
12
13
LINE_IN_L
AC97LINE_R
GND
GND
AC97CD_GND
AC97AUX_R
AUXIN_L
LINE_IN_R
AC97LINE_L
AC97MIC
AC97CD_R
AC97CD_L
AC97AUX_L
14
AUXIN_R
© 2000 California Micro Devices Corp. All rights reserved.
9/27/2000 215 Topaz Street, Milpitas, California 95035
Tel: [phone]
Fax: [phone]
C0441098
www.calmicro.com
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