TDA4455

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 1–2 and Pins 17–18), 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°) 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). 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 (Pin 11), so that negative or positive modulated IF signals are always available with the same polarity at the demodulator 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 cha...