Document Outline
- FEATURES
- GENERAL DESCRIPTION
- QUICK REFERENCE DATA
- ORDERING INFORMATION
- PINNING
- FUNCTIONAL DESCRIPTION
- Vision IF amplifier and demodulator
- Synchronous demodulator
- Video buffer amplifier
- AGC detector and IF gain control
- Sync pulse separator
- Tuner AGC
- Identification
- Tracking generator (AFT)
- LIMITING VALUES
- CHARACTERISTICS
- PACKAGE OUTLINE
- SOLDERING
- DEFINITIONS
- LIFE SUPPORT APPLICATIONS
DATA SHEET
Preliminary specification
File under Integrated Circuits, IC02
January 1992
INTEGRATED CIRCUITS
TDA3853T
TV IF amplifier and demodulator
with TV-identification
January 1992
2
Philips Semiconductors
Preliminary specification
TV IF amplifier and demodulator with
TV-identification
TDA3853T
FEATURES
Suitable for standards B/G (I, M, N, DK), see Table 1
Gain controlled 3-stage IF amplifier with typically
80 MHz bandwidth
High performance synchronous demodulator for
negative and positive video modulation; passive
regeneration of the reference signal
Peak-sync-related AGC
AGC output voltage take over point adjustable
High sensitive TV identification based on vertical pulse
duty cycle recognition; IDENT output
Video off switch
Sound trap buffer amplifier
Tracking generator (AFT output) with Q-demodulator
and internal 90 degree phase shifter for tracking the
reference circuit
Low supply voltage 5 V, low power consumption
GENERAL DESCRIPTION
Monolithic integrated circuit for vision IF signal processing
in TV and VTR sets.
QUICK REFERENCE DATA
ORDERING INFORMATION
Note
1. SOT163-1; 1997 January 8.
SYMBOL
PARAMETER
MIN.
TYP.
MAX.
UNIT
V
P
supply voltage
4.75
5
6
V
I
P
supply current
-
46
-
mA
V
i
vision IF input signal sensitivity (RMS value, pins 1-20)
-
70
100
V
maximum vision IF input signal (RMS value, pins 1-20)
100
-
-
mV
G
v
IF gain control range
63
66
-
dB
V
o CVBS
buffered CVBS output signal on pin 12 (peak-to-peak value)
1.7
2
2.3
V
B
-
3 dB video bandwidth (pin 12)
-
14
-
MHz
S/N
signal-to-noise ratio for video
55
60
-
dB
1.1
intermodulation attenuation at yellow
53
56
-
dB
3.3
60
-
-
dB
spur
suppression of spurious harmonics of video signal
22
26
-
dB
T
amb
operating ambient temperature
0
-
70
C
EXTENDED
TYPE NUMBER
PACKAGE
PINS
PIN POSITION
MATERIAL
CODE
TDA3853T
20
mini-pack
plastic
SOT163A
January 1992
3
Philips Semiconductors
Preliminary specification
TV IF amplifier and demodulator with
TV-identification
TDA3853T
Fig.1 Block diagram.
January 1992
4
Philips Semiconductors
Preliminary specification
TV IF amplifier and demodulator with
TV-identification
TDA3853T
PINNING
SYMBOL
PIN
DESCRIPTION
V
i a
1
balanced vision IF input a
TOP
2
tuner AGC take over adjustment point (TOP)
C
BL
3
capacitor for black level
n.c.
4
not connected
VIDOFF
5
video off input, identification capacitor
IDENT
6
TV identification output
TRSW
7
set input for tracking switch, tracking hold capacitor
AFT
8
automatic frequency tracking output
n.c.
9
not connected
RES1
10
resonance reference circuit for vision carrier
RES2
11
resonance reference circuit for vision carrier
CVBS
12
CVBS output (positive)
TRAP
13
video buffer amplifier input from sound trap
VIDEO
14
video and sound intercarrier output
V
P
15
+
5 V supply voltage
C
stab
16
decoupling capacitor for voltage stabilizer
GND
17
ground (0 V)
C
AGC
18
capacitor for AGC
AGC
19
AGC output to tuner
V
i b
20
balanced vision IF input b
Fig.2 Pin configuration.
FUNCTIONAL DESCRIPTION
The TDA3853T is a TV IF
amplifier/demodulator for negative
modulation.
The IF input signal is amplified,
gain-controlled and demodulated
(Fig.1).
Vision IF amplifier and
demodulator
The vision IF amplifier consists of
three AC-coupled differential
amplifiers. Gain control is achieved by
current divider stages. Emitter
feedback resistors in the differential
amplifiers are optimized with respect
to noise and signal capability.
Synchronous demodulator
The demodulator has a reference
amplifier consisting of a differential
amplifier with resistive load to provide
passive vision carrier regeneration.
This allows capacitive coupling of the
resonance circuit to obtain a notch
filter characteristic and tracking of the
resonance circuit.
A cascaded limiter amplifier follows
the reference amplifier to eliminate
amplitude modulation. The limited IF
reference signal is fed to the
demodulator. The unlimited IF signal
is fed via a phase correction network
to the demodulator. The video
amplifier is an operational amplifier
with a wide bandwidth and internal
feedback. The video and sound
intercarrier signal is output on pin 14.
Video buffer amplifier
This operational amplifier has a wide
bandwidth with internal feedback and
frequency compensation. Gain and
input impedance are adapted to
operate with a ceramic sound trap.
The switching functions are described
in Table 1.
AGC detector and IF gain control
The video signal is fed through
low-pass filters to attenuate the sound
carriers and then is fed to the AGC
detector.
Peak-sync AGC detection.
A special network provides current
pulses to fast charge the AGC
capacitor on pin 18 (gain reduction).
This achieves a minimum of video
distortion.
The AGC control converts the AGC
capacitor voltage to three separate
voltages to control the IF stages.
January 1992
5
Philips Semiconductors
Preliminary specification
TV IF amplifier and demodulator with
TV-identification
TDA3853T
Sync pulse separator
The sync pulse separator separates
the composite sync signal to gate the
AFT. The vertical sync is used for
identification. The input is
band-limited to obtain a higher ident
sensitivity.
Table 1
Switching functions of TDA3853T.
Note
1. capacitor on pin 7 means tracking active; LOW means tracking inactive
VIDOFF
PIN 5
TRSW
PIN 7
VIDEO
SIGNAL
IDENT
PIN 6
pin
L
L
(1)
video OFF
0.5 mA sink
setting
2.2
F
L
(1)
video ON
H or 0.5 mA sink
Tuner AGC
The tuner AGC output current is fed to
the open-collector output on pin 19.
The take-over point is adjusted
externally at pin 2 to adapt the tuner
and SAW filter to an optimum IF input
level. The IF gain variation over the
full tuner gain range (slip) is
minimized to ensure a constant tuner
output signal.
Identification
An analog integrating network
followed by a window comparator
identifies the video signal by detection
of the duty cycle of the vertical sync
pulses. The pulses charge the
identification capacitor on pin 5.
Tracking generator (AFT)
A limited 90 degree phase-shifted
vision carrier signal is fed to the AFT
quadrature demodulator, internal RC
networks provide active phase
shifting. The linear IF signal is applied
to the other AFT quadrature
demodulator input. The AFT output
signal is applied to a gating stage.
Gating with the composite sync
pulses activates the AFT
demodulator. Therefore the AFT
output is free from video modulation.
The AFT capacitor (pin 7) is charged
by the gated AFT current. The
capacitor voltage is converted to an
DC output current on pin 9
(open-collector sink/source currents).
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