TEA0675T PHILIPS [NXP Semiconductors], TEA0675T Datasheet - Page 10

• Manufacturer Part Number: TEA0675T
• Description: Dual Dolby* B-type noise reduction circuit for playback applications
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
Short description ‘music search’
A system for ‘music search’ mainly consists of a level and
a time detection (see Fig.4). For adapting and decoupling
the input signal will be amplified (A), then rectified (B) and
smoothed with a time constant (C). So the voltage at (C)
corresponds to the signal level and will be compared to the
predefined pause level at the first comparator (D), the level
detector. If the signal level becomes smaller than the
pause level, the level detector changes its output signal.
Due to the output level of the level detector the capacitor
of the second time constant (E) will be charged,
1996 Jun 07
handbook, full pagewidth
Dual Dolby* B-type noise reduction circuit
for playback applications
INPUT
AMPLIFIER
(A)
RECTIFIER
(B)
Fig.4 Integrated ‘music search’ function.
(C)
t 1
V I
LEVEL DETECTOR
COMPARATOR 1
10
respectively discharged. If the pause level of the input
signal remains for a certain time, the voltage at the
capacitor reaches a certain value, which corresponds to
an equivalent time value. The voltage at the capacitor will
be compared to a predefined time-equivalent voltage by
the second comparator (F), the time detector. If the pause
level of the input signal remains for this predefined time,
the time detector changes its output level for ‘pause found’
status.
(D)
(E)
t 2
V t
TIME DETECTOR
COMPARATOR 2
(F)
Preliminary specification
MED624
OUTPUT
TEA0675