Linear Audio

Appendix

1Outline

This audio circuit uses a LA71598SM Super A/V 1 chip IC made by SANYO.

The major features of this IC is that REC/EE mode, PB/EE mode, SP/LP mode and audio input selection are controlled by parallel.

21 pin ( 1~9 pin, 75~80 pin, and 95~100 pin ) are related to Audio circuit.

2Audio IC : name and operation of pins

A. Features

Including PB Amp, Line Amp, REC Amp, ALC circuit, EQ switch and Auto REC bias circuit.

It is equipped with EQ switch operates in SP/LP mode respectively.

ALC level is fixed on 4dBm by values.

B. Function

Pin No.	Name	Function

1	EQ-OUT	Playback Amp output

2	EQ-SW2	Capacitor switch for head resonance: in SP or LP, SW ON

3	EQ-NFB	Negative feedback of PB Amp

4	EQ-IN	Input impedance : 120Kohm

5	EQ-SW1	Playback equalizer switch : in SLP mode, SW ON

6	AUTO-BIAS IN	70KHz signal input for auto-bias

7	AUDIO REC OUT	Recording Amp out

8	REC-NFB-SP(GND)	GND

9	REC-NFB-LP(GND)	GND

75	AUDIO VCC(5V)	Vcc ( 5V )

76	AUDIO-IN	Audio in

77	ALC-DET	Port for ALC Filter

78	AUDIO-IN2	Audio in

79	VREF	Vref filter

80	AUDIO-IN3	Audio in

95	AUDIO-GND	GND

96	AUDIO-LINE-OUT	Line Amp output

97	ALC-IN	ALC detect

98	AUDIO-REC-IN	Input to REC Amp

99	AUTO-BIAS-OUT	DC control voltage for auto-bias

100	AUDIO-PB-IN	Line Amp input of PB Amp out