LM1291N National Semiconductor, LM1291N Datasheet

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LM1291N

Manufacturer Part Number
LM1291N
Description
Video PLL System for Continuous Sync Monitors
Manufacturer
National Semiconductor
Datasheet

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C 1995 National Semiconductor Corporation
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 selec-
tion 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 polar-
ities
The 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 oper-
ation over the entire frequency range using just one opti-
mized set of external components
The system includes a second phase detector which com-
pensates for storage time variation in the horizontal output
transistor the picture’s horizontal position is thus indepen-
dent of temperature and component variance
The LM1291 provides DC control pins for H Drive duty cycle
and flyback phase
Connection Diagram
TL H 12323
See NS Package Number N28B
Order Number LM1291N
FIGURE 1
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 external adjust-
ments
No manufacturing trims required internal VCO capaci-
tor trimmed on chip
No costly high-precision components needed
Low phase jitter (1 3 ns at 100 kHz)
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 V
powered down
H drive disabled for V
Horizontal output transistor protected against accidental
turn-on during flyback
Capacitor-programmable frequency ramping df
protects H output transistor during scanning mode
changes
CC k
TL H 12323– 1
9 5V
RRD-B30M115 Printed in U S A
June 1995
VCO
CC
dt

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LM1291N Summary of contents

Page 1

... H drive disabled for Horizontal output transistor protected against accidental Y turn-on during flyback Capacitor-programmable frequency ramping df Y protects H output transistor during scanning mode changes FIGURE 1 Order Number LM1291N See NS Package Number N28B June 1995 VCO TL H 12323– 1 RRD-B30M115 Printed ...

Page 2

... Absolute Maximum Ratings If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Supply Voltage Input Voltage V DC Pins 15 23 Pins 4 5 Pins 8 28 Pins Power Dissipation ( (Above 25 C Derate Based on and T JA ...

Page 3

... SET SET 15k SET SET 0 025 T and the ambient temperature T Jmax the number given in the Absolute Maximum Ratings whichever is lower For Jmax these parts when board mounted follow LM1291N resistor where 12V (Continued) Limit Units (Note (max (max (max (min) ...

Page 4

Test Circuit 4 ...

Page 5

Block Diagram Pin Descriptions See Figures 4 through 15 for input and output schematics Pin 1 - CLAMP CNTL This low-impedance current-mode input pin is internally biased to 2V The direction of current sets the pulse position (back porch or ...

Page 6

Pin Descriptions (Continued) Pin SYNC OUT The sync processor outputs active-low H HV sync derived from the active sync input (pin 9 or pin 12) Pin 11 stays low in the absence of sync input See ...

Page 7

Application Hints (Continued) 3 Video mute Numerous designs require video blanking during scanning mode transitions The LM1291 provides an active-low pulse at pin 3 when triggered by a step change of H sync frequen- cy from The ...

Page 8

Input Output Schematics (Continued 12323 – 7 FIGURE 12323 – 8 FIGURE 12323– 9 FIGURE 9 8 ...

Page 9

Input Output Schematics (Continued) FIGURE 10 FIGURE 12 FIGURE 12323 – 12323 – 12323 – 12323– 11 FIGURE 12323– 13 FIGURE ...

Page 10

Typical Application 10 ...

Page 11

11 ...

Page 12

... Italiano National does not assume any responsibility for use of any circuitry described no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications Order Number LM1291N NS Package Number N28B 2 A critical component is any component of a life ...

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