TEA0678 データシートの表示（PDF） - Philips Electronics

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TEA0678

Dual Dolby* B-type noise reduction circuit, automatic music search, with differential outputs and mute

Philips Electronics 

Philips Semiconductors

Preliminary specification

Dual Dolby* B-type noise reduction circuit, automatic

music search, with differential outputs and mute

TEA0678

FEATURES

• Dual noise reduction (NR) channels

• Head pre-amplifiers

• Reverse head switching

• Automatic Music Search (AMS)

• Mute position

• Equalization with electronically switched time constants

• Dolby reference level = 387.5 mV

• 32 pins

• Switch inputs TTL compatible

• Differential output stage has:

– Capability to drive 1.2 nF capacitive load

– Capability to drive 1 kΩ load

– Short-circuit proof

– Short-circuit proof to 16 V via coupling capacitor.

• Improved EMC behaviour.

GENERAL DESCRIPTION

The TEA0678 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. Furthermore it includes electronically

switchable inputs for tape drivers with reverse heads.

This device also detects pauses of music in Automatic

Music Search (AMS) mode, with a delay time fixed

externally by a resistor. The short-circuit proof output

stage of the TEA0678 is differential and provides muting.

The device will operate with power supplies in the range of

7.6 to 12 V, output overload level increasing with increase

in supply voltage. Current drain varies with supply voltage,

noise reduction on/off and AMS on/off so it is advisable to

use a regulated power supply or a supply with a long time

constant.

.Current drain varies with these 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.

10

25

84

MAX.

12

28

−

UNIT

V

mA

dB

ORDERING INFORMATION

TYPE

NUMBER

TEA0678

TEA0678T

NAME

SDIP32

SO32

PACKAGE

DESCRIPTION

plastic shrink dual in-line package; 32 leads (400 mil)

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

VERSION

SOT232-1

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.

1996 Jun 06

2

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