LM1291

LM1291 Video PLL System for Continuous-Sync Monitors June 1995 LM1291 Video PLL System for Continuous-Sync Monitors General Description The LM1291 is an integrated horizontal time base solution specifically designed to operate in continuous-sync video monitors It automatically synchronizes to any H frequency from 22 kHz to 125 kHz and provides the drive pulse to the high power deflection circuit Available sync processing includes a vertical sync separator and a composite video sync stripper An internal sync selection scheme gives highest priority to separate H and V sync then composite sync and finally sync on video no external switching between sync sources is necessary The LM1291 provides polarity-normalized H HV and V sync outputs along with logic flags which show the respective input polarities The design uses an on-chip FVC (Frequency-to-Voltage Converter) to set the center frequency of the VCO (VoltageControlled Oscillator) This technique allows autosync operation over the entire frequency range using just one optimized set of external components The system includes a second phase detector which compensates for storage time variation in the horizontal output transistor the picture’s horizontal position is thus independent of temperature and component variance The LM1291 provides DC control pins for H Drive duty cycle and flyback phase Features Y Y Y Y Y Y Y Y Y Y Y Y Y Y Wide continuous autosync range 22 kHz to 125 kHz (1 5 7) with no component switching or ex...