PACAC97 California Micro Devices Corp, PACAC97 Datasheet - Page 2

• Manufacturer Part Number: PACAC97
• Description: PC AUDIO RESISTOR NETWORK
• Manufacturer: California Micro Devices Corp

©2000 California Micro Devices Corp. All rights reserved.
2
R1, R2 and R3, R4 provide 6dB pads for the LINE-IN
stereo signals in order to scale a 2Vrms input to a
1Vrms Codec input. Similarly, R5, R6, R7, R8 and R9,
R10, R13, R14 provide the necessary attenuation for
the AUX and CD signals going to the Codec. With an
external Operational Amplifier, resistors R17 and R18
provide nominally 27dB of gain for the microphone
signal (non-inverting amp). R15, R16 divide down the
microphone output signal, thereby protecting the Codec
from any transient voltages coming from the microphone
amplifier. This is particularly important if this amplifier
runs of +12V supplies. The R15/R16 divider can be
bypassed with an external 0Ω jumper connection, if so
desired. Bias voltage needs to be provided for con-
denser type microphones. Resistors R21, R22, R23 and
R24 are the gain setting resistors for the headphone
amplifier. The gain is set at 3.5dB with the output
amplifiers in an inverting configuration. The output gain
can be changed with the addition of external resistors,
215 Topaz Street, Milpitas, California 95035
CODEC
CODEC
TO
TO
CALIFORNIA MICRO DEVICES
CD GND IN
R LINE IN
L LINE IN
R AUX IN
L AUX IN
R CD IN
L CD IN
MIC IN
LINE IN
+
+
+
+
+
+
+
+
GND
TYPICAL APPLICATIONS CIRCUIT
Tel: [phone]
AUX IN
P1
P2
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
P13
P14
GND
PACAC97
allowing for maximum design flexibility. The resistors are
referenced as Amp1 and Amp2 rather then Left and
Right to provide added flexibility for board layout. LINE-
IN, LINE-OUT and MIC jack signals are externally de-
coupled in order to minimize EMI.
Crosstalk Test Circuit
Cross talk is a critical parameter for high quality audio.
Specifically, stereo cross talk (Left to Right) and channel
to channel cross talk must be minimized. For this reason
much attention has been paid to the circuit layout of the
PACAC97 in order to provide the necessary damping for
signals in the 20Hz–20KHz audio band. Three examples
are provided to illustrate inter-channel and channel-
channel cross talk measurements that have been
performed on the PACAC97. Similar measurements were
performed for all audio functions deemed critical be-
cause of layout considerations.
P28
P27
P27
P26
P25
P24
P23
P22
P21
P20
P19
P18
P17
P16
P15
ATAPI CD IN
Fax: [phone]
–
+
–
–
+
+
R LINE OUT
L LINE OUT
www.calmicro.com
MIC BIAS
GND
LINE OUT
GND
PACAC97
MIC
FROM
CODEC
9/27/2000