مدار مجتمع (آی سی) آی سی‌کاربرد ویژه

Product Attributes

Introduction

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 22kHz to 125kHz 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 (Voltage. Controlled Oscilator). 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

• Wide continuous autosync range—22kHz to 125kHz (1 :5.7) with no component switching or external adjustments
• No manufacturing trims required, internal VCO capacitor trimmed on chip
• No costly high-precision components needed
• Low phase jitter (1.3 ns at 100kHz)
• DC controlled H phase and duty cycle
• Video mute pulse for blanking during H frequency transitions
• Input sync prioritization
• Clamp pulse position and width control
• Continuous clamp pulse output, even with no sync input
• Resistor-programmable minimum and maximum VCO frequency
• X-ray input disables H drive and mutes video until VCC powered down
• H drive disabled for VCC < 9.5V
• Horizontal output transistor protected against accidental turn-on during flyback
• Capacitor-programmable frequency ramping, dfVCO/dt, protects H output transistor during scanning mode changes