LM1292 Video PLL System for Continuous-Sync Monitors General Description The LM1292 is a very low jitter, integrated horizontal time base solution specifically designed to operate in high performance, 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 LM1292 provides polarity-normalized H/HV and V sync outputs. The LM1292 design uses an on-chip FVC (Frequency-to-Voltage Converter) to set the center frequency of the VCO (Voltage-Controlled 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 LM1292 provides DC control pins for H Drive duty cycle and flyback phase. Features n Wide continuous autosync range—22 kHz–125 kHz (1:5.7) with no component switching or external adjustments n No manufacturing trims required—internal VCO capacitor trimmed on chip n No costly high-precision components needed n Very low phase jitter (below 800 ps at 125 kHz) n DC controlled H phase and duty cycle n Video mute pulse for blanking during H frequency transitions n Input sync prioritization n Clamp pulse position and width control n Continuous clamp pulse output, even with no sync input n Resistor-programmable minimum and maximum VCO frequency n X-ray input disables H drive and mutes video until VCC powered down n H drive disabled for VCC < 9.5V n Horizontal output transistor protected against accidental turn-on during flyback n Capacitor-programmable frequency ramping, df vco/dt, protects H output transistor during scanning mode changes