TEA0675T PHILIPS [NXP Semiconductors], TEA0675T Datasheet - Page 5

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

Philips Semiconductors
FUNCTIONAL DESCRIPTION
Noise Reduction (NR) is enabled when pin HPB is
open-circuit and disabled when connected to GND via an
1.5 k resistor.
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 V
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 k resistor 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.
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
Notes
1. Human body model (1.5 k , 100 pF).
2. Machine model (0 , 200 pF).
1996 Jun 07
V
V
t
T
T
V
SYMBOL
short
stg
amb
CC
i
es
Dual Dolby* B-type noise reduction circuit
for playback applications
supply voltage
input voltage (except pin 11)
pin 11 (V
storage temperature
operating ambient temperature
electrostatic handling voltage for all pins
ref
) to V
CC
CC
PARAMETER
short-circuiting duration
via an 1.5 k resistor
5
Equalization time constant switching (70 s or 120 s)
is achieved when pin AMSEQ is connected to GND via an
18 k resistor (120 s), or left open-circuit (70 s).
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 k resistor, or left
open-circuit (input IN1 active). The 10 F 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.
note 1
note 2
CONDITIONS
0
0.3
55
40
2
500
MIN.
Preliminary specification
14
+V
5
+150
+85
+2
+500
MAX.
CC
TEA0675
V
V
s
kV
V
C
C
UNIT