U4462B-B

The U4462B-B has the following features including 5 V supply voltage; low power consumption;Minimum number of external components;Active  carrier  generation  by  FPLL  principle frequency-phase-locked-loop) for true synchronous demodulation;Very finear  video  demodulation,  excellent pulse response and good intermodulation figures;VCO circuit is operating on picture carrier frequency;Alignment-free  AFC  without  external  reference circuit;VIF-AGC with peak sync detection;Tuner AGC with adjustable take-over point;Completely  alignment-free PLL  demodulator  for FM-intercarrier sound IF signals (mono).

The U4462B is a a video/sound IF concept for TV-IF signal processing. The circuit processes all video IF signals with negative modulation and FM sound IF signals (mono FM intercarrier sound). With 5 V supply voltage, the U4462B is suitable for TV,VCR and multimedia applications.The video IF signal (VIF) is fed through a SAW filter to the differential input(pin 5-6) of the VIF amplifier. This amplifier consists of three ac-coupled amplifier stages.Each differential amplifier is gain controlled by the automatic gain control (VIF-AGC). The output signal of the  VIF  amplifier  is  applied  to  the FPLL  carrier generation and the video demodulator.A practicable VCO alignment of the external coil is the adjustment to zero AFC output current at Pin 20. At center frequency the AFC output current is equal to zero. The optional potentiometer  at Pin  26  allows  an  offset compensation of the VCO phase for improved sound quality (fine adjustment). Without a potentiometer (open circuit at Pin 26), this offset compensation is not active.

The video IF signal, U4462B-B is applied from the gaincontrolled IF amplifier, is multiplied with the in-phase component of the VCO signal. The video demodulator is designed for low distortion and large bandwidth. The demodulator output signal passes an integrated low-pass filter for attenuation of the residual vision carrier and U4462B-B is fed to the video amplifier. The video amplifier is realized by an operational amplifier with internal feedback and 8 MHz bandwidth.  An  additional  noise  clipping is provided. The video signal is fed to VIF-AGC and to the video output buffer. This amplifier offers easy adaptation of the sound trap and sound filter. For nominal video IF modulation, the video output signal at Pin 16 is 1.5 V(peak-to-peak value).