PACAC97 datasheet(2/4 Pages) CALMIRCO

2 / 4 page

9/27/2000

215 Topaz Street, Milpitas, California 95035

Tel: (408) 263-3214

Fax: (408) 263-7846

www.calmicro.com

PACAC97

CALIFORNIA MICRO DEVICES

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 0

Ω 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,

TYPICAL APPLICATIONS CIRCUIT

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.

LINE IN

LINE OUT

GND

MIC

GND

PACAC97

R LINE IN

P28

P27

P26

P25

P24

P23

P22

P21

P20

P10

P19

P11

P18

P12

P17

P13

P16

P14

AUX IN

P15

MIC IN

R CD IN

CD GND IN

L CD IN

CODEC

R AUX IN

L AUX IN

L LINE IN

ATAPI CD IN

CODEC

FROM

CODEC

–

MIC BIAS

L LINE OUT

R LINE OUT

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