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NXP Semiconductors |
INTEGRATED CIRCUITS
DATA SHEET
TEA0678
Dual Dolby* B-type noise reduction
circuit, automatic music search,
with differential outputs and mute
Preliminary specification
Supersedes data of August 1993
File under Integrated Circuits, IC01
1996 Jun 06
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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