Service manual

SERVICE MANUAL
IC DATA AND WAVEFORMS OF KEY POINTS
(continued)
TDA9808T
Single Standard VIF-PLL with QSS-IF and FM-PLL Demodulator
1.Features
˙5V supply voltage (9V supply voltage for
TDA9808(DIP20) only)
˙Applicable for IFs (lntermediate Frequencies) of
38.9MHz, 45.75MHz and 58.75 MHz
˙Gain controlled wide band Video IF (VIF)-
amplifier (AC-coupled)
˙ True synchronous demodulation with active
carrier regeneration (very linear demodulation,
good intermodulation figures, reduced harmonics,
excellent pulse response)
˙ Robustness for over-modulation better than
105% due to Phase Locked Loop (PLL)-
bandwidth control at negative modulated
standards
˙VIF Automatic Gain Control (AGC) detector for
gain control, operating as peak sync detector
˙Tuner AGC with adjustable TakeOver Point (TOP)
˙Automatic Frequency Control (AFC) detector
without extra reference circuit
˙AC-coupled limiter amplifier for sound intercarrier
signal
˙Alignment-free FM-PLL demodulator with high
linearity
˙Sound IF (SIF) input for single reference Quasi
Split Sound (QSS) mode (PLL controlled); SIF
AGC detector for gain controlled SIF amplifier;
single reference QSS mixer for high performance
˙Electrostatic Discharge (ESD) protection for all
pins.
2.General Description
The TDA9808 is an integrated circuit for
single standard (negative modulated) vision
IF signal processing and FM demodulation,
with single reference QSS-IF in TV and VTR
sets.
20