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TEA0675T View Datasheet(PDF) - Philips Electronics

Part Name
Description
Manufacturer
TEA0675T Datasheet PDF : 32 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
Philips Semiconductors
Dual Dolby* B-type noise reduction circuit
for playback applications
Preliminary specification
TEA0675
FUNCTIONAL DESCRIPTION
Noise Reduction (NR) is enabled when pin HPB is
open-circuit and disabled when connected to GND via an
1.5 kresistor.
Dolby B noise reduction only operates correctly if 0 dB
Dolby level is adjusted at 387.5 mV.
Automatic Music Search (AMS) scan mode is enabled
when pin HPA is connected to VCC via an 1.5 kresistor
and disabled when pin HPA is open-circuit. Switching AMS
on, internally NR is switched OFF simultaneously
(see Figs 5 and 6 for principle timing in AMS-scan mode).
AMS-latch mode is enabled when pin HPA is connected
to GND via an 1.5 kresistor and disabled when pin HPA
is open-circuit. Switching AMS on, NR is switched off
internally. In this mode the device detects a pause level
signal, when a music level signal has appeared first
(see Figs 7 and 8 for principle timing). Furthermore a
longer rise time constant is supplied for suppressing the
detection of plops on tape. The output signal at pin
AMSEQ in this mode may be applied to drive a tape driver
logic circuit.
Equalization time constant switching (70 µs or 120 µs)
is achieved when pin AMSEQ is connected to GND via an
18 kresistor (120 µs), or left open-circuit (70 µs).
This does not affect the AMS output signal during AMS
mode (see Fig.1).
Head switching is achieved when pin HS is connected
(input IN2 active) to GND via a 27 kresistor, or left
open-circuit (input IN1 active). The 10 µF capacitor at pin
HS sets the time constants for smooth switching.
In AMS mode the signals of both channels are rectified and
then added. This means, even if one channel signal
appears inverted to the other channel, the normal AMS
function is ensured. Pins HPB and HPA perform the
function of a logic input for AMS, respectively NR mode
switching in both channels and provide the frequency
dependent feedback of the control chain amplifier in the
corresponding channel. Thus it is important that no voltage
is applied to pins HPB and HPA during NR on/AMS off
mode, otherwise this will cause irregular NR
characteristics.
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
SYMBOL
PARAMETER
VCC
Vi
tshort
Tstg
Tamb
Ves
supply voltage
input voltage (except pin 11)
pin 11 (Vref) to VCC short-circuiting duration
storage temperature
operating ambient temperature
electrostatic handling voltage for all pins
CONDITIONS MIN.
0
note 1
note 2
0.3
55
40
2
500
Notes
1. Human body model (1.5 k, 100 pF).
2. Machine model (0 , 200 pF).
MAX.
14
+VCC
5
+150
+85
+2
+500
UNIT
V
V
s
°C
°C
kV
V
1996 Jun 07
5
 

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