TELEFUNKEN Semiconductors
TDA4455
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
picture carrier regeneration gives a high performance of
linear video demodulation.
With two IF inputs (Pins 1鈥? and Pins 17鈥?8), it is
possible to select between two signal sources. The input
selector switch (Pin 16) works independent from the
standard switch (Pin 11).
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擄) with the output signal of the VCO (90擄) 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).
A second output of the VCO (0擄) provides the reference
carrier for the video demodulator. The polarity of the
demodulator can be inverted by the standard switch
(Pin 11), so that negative or positive modulated IF signals
are always available with the same polarity at the demo-
dulator output. The demodulated video signal is filtered,
amplified and fed via an interference limiter to the video
output (Pin 7).
The standard switch also determines the clamp level of
the video amplifier and the required IF-AGC mode. In the
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.
An overload detector prevents the PLL becoming
unlocked by large IF input signals.
To achieve a delayed tuner-AGC action, the current out-
put (Pin 4) can be adjusted with a resistor at Pin 3.
Features
D
Suitable for standard B/G, L and D2MAC, processes
negative and positive modulated IF-signals with equal
polarity of the output signal
D
Standard L: fast AGC acting on peak white level with
average value controlled capacitor discharge and
reference hysteresis
D
Two IF-inputs, for switching between two signal
sources (e.g., two tuners and two SAW-filters)
D
D2MAC: fast AGC acting on peak level with
controlled capacitor discharge
D
Output for delayed tuner-AGC, take over point
adjustable
D
High performance video demodulator with PLL
picture carrier regeneration
D
Extended video bandwidth (12 MHz) for the demodu-
lation of amplitude modulated MAC-signals
D
Standard B/G: AGC acting on the sync peak pulse
D
D
D
D
D
High input sensitivity
Ultra white and ultra black limiting
Supply voltage range 6.8 to 13 V
Low power consumption
ESD protection
Package Options
Case: 18-pin DIL plastic
Rev. A1: 08.05.1995
Preliminary Information
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