TDA1596T CNV, ELEKTRONIKA, ELEKTRONIKA MIESZANA
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INTEGRATED CIRCUITS
DATA SHEET
TDA1596T
IF amplifier/demodulator for FM
radio receivers
April 1991
Product specification
File under Integrated Circuits, IC01
Philips Semiconductors
Product specification
IF amplifier/demodulator for FM radio
receivers
TDA1596T
GENERAL DESCRIPTION
The TDA1596T provides IF amplification, symmetrical quadrature demodulation and level detection for quality home and
car FM radio receivers and is suitable for both mono and stereo reception. It may also be applied to common front-ends,
stereo decoders and AM receiver circuits.
Features
·
Simulates behaviour of a ratio detector (internal field strength and detuning-dependent voltage for dynamic AF signal
muting)
·
Mono/stereo blend and field strength indication control voltage
·
Three-state mode switch for FM, mute-on / FM, mute-off / FM-off
·
Internal compensation of AF signal total harmonic distortion (THD)
·
Two open collector stop pulse outputs for microcomputer tuning control (can be one stop pulse output by
wired-ANDing)
·
Internal reference voltage source
·
Built-in hum and ripple rejection circuits.
QUICK REFERENCE DATA
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
V
P
Supply voltage (pin 1)
7.5
8.5
12.0
V
I
P
Supply current (pin 1)
V
P
= 8.5 V; I
2
= I
7
= 0 mA
-
20
26
mA
V
4(rms)
AF output voltage (RMS value)
V
20(rms)
= 10 mV
180
200
220
mV
S/N
Signal-to-noise ratio
V
20(rms)
= 10 mV; f
m
= 400 Hz;
D
82
dB
-
-
f = 75 kHz
THD
Total harmonic distortion
V
20(rms)
= 10 mV; f
m
= 1 kHz;
I
7
= 0 mA;
D
f = 75 kHz; FM mute
on; without de-emphasis;
without detuning
-
0.1
0.3
%
T
amb
Operating ambient temperature
range
-
40
-
+
85
°
C
SEE ALSO DATA SHEET FOR TDA1596
PACKAGE OUTLINE
20-lead mini-pack; plastic (SO20; SOT163A); SOT163-1; 1996 August 12.
April 1991
2
(1)
Connecting pin 13 to ground is only allowed for measuring the current at pin 16. It is not for use in application.
(2)
In the FM, mute-on condition the unweighted level detector output is available from pin 3. In the FM, mute-off condition the variable resistor at pin 3 can be adjusted for
minimum 2nd harmonic distortion at pin 4.
Fig.1 Block diagram and application circuit.
Philips Semiconductors
Product specification
IF amplifier/demodulator for FM radio
receivers
TDA1596T
PINNING
1
supply voltage
P
2
LVA
level voltage adjustment
3
ULV
unweighted level output/K2 adjustment
4
AF0
AF output
5
ref
reference voltage output
6
WLV
weighted level voltage output
7
MSW
mode switch
8
DDV
detune detector voltage
9
n.c.
not connected
10
DMI1
demodulator input 1
11
DMI2
demodulator input 2
12
n.c.
not connected
13
TSW
tau switch
14
ST1
stop pulse output 1
15
ST0
stop pulse output 0
16
MTV
mute voltage
17
GND
ground
18
LFD1
IF limiter feedback 1
19
LFD2
IF limiter feedback 2
Fig.2 Pinning diagram.
20
IFI
IF input
April 1991
4
Philips Semiconductors
Product specification
IF amplifier/demodulator for FM radio
receivers
TDA1596T
FUNCTIONAL DESCRIPTION
Limiter-amplifier
This has five stages of IF amplification using balanced differential limiter-amplifiers with emitter--follower coupling.
Decoupling of the stages from the voltage supply lines and an internal high-ohmic DC feed-back loop give a very stable
IF performance. The amplifier gain is virtually independent from temperature changes.
FM demodulator
The demodulator is fully balanced and comprises two cross-coupled differential amplifiers. Quadrature detection of the
FM signal is performed by feeding one differential amplifier directly from the limiter--amplifier output, and the other via an
external 90
phase-shifting network. The demodulator has good stability and its zero cross-over shift is small. The
bandwidth of the demodulator output is restricted to approximately 1 MHz by an internal low-pass filter.
°
THD compensation
This circuit compensates non-linearities introduced by demodulation. For this to operate correctly the demodulator circuit
between pins 10 and 11 must have a loaded Q-factor of 19. Consequently there is no need for the demodulator tuned
circuit to be adjusted for minimum THD, instead the adjustment criterium is for a symmetrical stop pulse.
Mute attenuator and AF output
The control voltage for the mute attenuator at pin 16 is generated from the values of the level detector and the detuning
detector outputs. The mute attenuator has a fast attack and a slow decay which is determined by the capacitor at pin 16.
The AF signal is passed via the mute attenuator to the output at pin 4.
A weighted control voltage, available from pin 6, is obtained from the mute attenuator control voltage via a buffer-amplifier
which introduces an additional voltage shift and gain.
Level detector
The level detector generates a voltage output which is proportional to the field strength of the input signal. The
unweighted level detector output is available when the mode switch is operating in the FM, mute-on condition.
Tuning-stop outputs
The open collector outputs STOP-0 and STOP-1 (from pins 15 and 14 respectively) are voltages derived from the
detuning level and the field strength of the input signal. If only one tuning-stop output is required, pins 14 and 15 may be
tied together.
April 1991
5
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