TDA4455
TELEFUNKEN Semiconductors
Multistandard VIF Amplifier and PLL Demodulator
Application
Monolithic integrated circuit for vision IF signal processing in multistandard TV and VTR sets.
Description
This multistandard video IF processing circuit with PLL are always available with the same polarity at the demo-
picture carrier regeneration gives a high performance of dulator output. The demodulated video signal is filtered,
linear video demodulation.
amplified and fed via an interference limiter to the video
output (Pin 7).
With two IF inputs (Pins 1–2 and Pins 17–18), it is
possible to select between two signal sources. The input The standard switch also determines the clamp level of
selector switch (Pin 16) works independent from the the video amplifier and the required IF-AGC mode. In the
standard switch (Pin 11).
standard B/G mode the sync peak value is the criterion for
a fast charge and discharge. In the standard L mode on the
other hand, fast AGC action is achieved by charging at
peak white level and discharging by the averaged video
signal (time constant on Pin 8). The response level for
discharge has a hysteresis. In the D2MAC mode a similar
function is applied to achieve the AGC, but with different
threshold levels.
The IF signal is internally fed via a 3-stage controlled
wideband amplifier to the video demodulator and the
phase detector. The phase detector compares the phase of
IF signal (0°) with the output signal of the VCO (90°) and
sets the VCO frequency accordingly. A lock detector
switches the PLL loop filter according to the state of the
PLL (locked-PLL slow, unlocked-PLL fast).
An overload detector prevents the PLL becoming
unlocked by large IF input signals.
A second output of the VCO (0°) provides the reference
carrier for the video demodulator. The polarity of the
demodulator can be inverted by the standard switch To achieve a delayed tuner-AGC action, the current out-
(Pin 11), so that negative or positive modulated IF signals put (Pin 4) can be adjusted with a resistor at Pin 3.
Features
Suitable for standard B/G, L and D2MAC, processes
negative and positive modulated IF-signals with equal
polarity of the output signal
Standard L: fast AGC acting on peak white level with
average value controlled capacitor discharge and
reference hysteresis
D2MAC: fast AGC acting on peak level with
controlled capacitor discharge
Two IF-inputs, for switching between two signal
sources (e.g., two tuners and two SAW-filters)
Output for delayed tuner-AGC, take over point
adjustable
High performance video demodulator with PLL
picture carrier regeneration
High input sensitivity
Ultra white and ultra black limiting
Supply voltage range 6.8 to 13 V
Low power consumption
ESD protection
Extended video bandwidth (12 MHz) for the demodu-
lation of amplitude modulated MAC-signals
Standard B/G: AGC acting on the sync peak pulse
Package Options
Case: 18-pin DIL plastic
Rev. A1: 08.05.1995
1 (12)
Preliminary Information
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