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 posite video sync stripper An internal sync selection scheme gives highest priority to separate H and V sync then posite 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 ponents The system includes a second phase detector which pensates for storage time variation in the horizontal output transistor the picture’s horizontal position is thus independent of temperature and ponent variance The LM1291 provides DC control pins for H Drive duty cycle and flyback phase.
