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TEA0679

I2C-bus controlled dual Dolby* B-type noise reduction circuit for playback applications

Philips Electronics 

Philips Semiconductors

I2C-bus controlled dual Dolby* B-type noise

reduction circuit for playback applications

Product specification

TEA0679T

FEATURES

• Dual Noise Reduction (NR) channels

• Head preamplifiers

• Reverse head switching

• Automatic Music Search (AMS)

• Blank skip

• Mute position

• Equalization with electronically switched time constants

• Switch functions and level adjustment controlled via

I2C-bus

• Optional switch inputs TTL compatible

• Dolby reference level = 387.5 mV

• Contained in a 32-pin small outline package

• Improved EMC behaviour.

GENERAL DESCRIPTION

The TEA0679T is a bipolar integrated circuit that provides

two channels of Dolby B noise reduction for playback

applications in car radios. It includes head and

equalization amplifiers with electronically switchable time

constants. The device also includes electronically

switchable inputs for tape drivers with reverse heads.

This device detects pauses of music in the Automatic

Music Search (AMS) scan mode (for applications with an

intelligent controlled tape driver) or AMS latch mode (for

applications with a simple controlled tape driver).

For both modes the delay time can be fixed by using an

external resistor. In the blank skip mode the IC can detect

pauses of music during playback and allows a

microcontroller to react on this situation.

The equalization amplifier gain adjustment, the output

offset adjustment and all switching functions are I2C-bus

controlled. Head switching and equalization time constant

switching can be controlled via separate pins (optional).

The device operates with power supplies from 7.6 to 12 V.

The output overload level increases with increases in

supply voltage.

Current drain varies with the following variables:

• Supply voltage

• Noise reduction on/off

• AMS on/off.

Because of this current drain variation it is advisable to use

a regulated power supply or a supply with a long time

constant.

QUICK REFERENCE DATA

SYMBOL

VCC

ICC

S------N+-----N---

PARAMETER

supply voltage

supply current

signal plus noise-to-noise ratio

MIN.

7.6

−

78

TYP.

−

35

84

MAX.

12

40

−

UNIT

V

mA

dB

ORDERING INFORMATION

TYPE

NUMBER

TEA0679T

NAME

SO32

PACKAGE

DESCRIPTION

plastic small outline package; 32 leads; body width 7.5 mm

VERSION

SOT287-1

Remark Dolby*: Available only to licensees of Dolby Laboratories Licensing Corporation, San Francisco, CA94111,

USA, from whom licensing and application information must be obtained. Dolby is a registered trade-mark of Dolby

Laboratories Licensing Corporation.

1998 Nov 12

2

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