NTE1739
Integrated Circuit
TV Horizontal/Vertical Countdown
Digital Sync System
Features:
D
Horizontal Oscillator
D
Vertical Countdown
D
Composite Blanking Output
D
BurstGate Output
D
Horizontal Ramp Generator
D
Internal Shunt Regulator
Description:
The NTE1739 is a video sync system in a 16Lead DIP type package designed for use in television,
monitor or video display products. The NTE1739 contains a horizontal phaselocked oscillator and
vertical countdown. It also features composite blanking and burstgate outputs which, when external-
ly summed, produce the sandcastle pulse necessary for the operation of most chroma/luma circuits.
The NTE1739 is intended for use in 525line systems and operates with standard or nonstandard
input signals. An automatic moderecognition circuit forces operation into the nonsynchronous mode
for nonstandard sync input signals.
Absolute Maximum Ratings:
DC Supply Current, Pin7
50mA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input Voltage (All Inputs)
1V to V+ + 1V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Device Dissipation (T
A
+85
C)
900mW
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Derate Linearly Above 85
C 14mW/
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Ambient Temperature Range
40
to +85
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage Temperature Range
65
to +150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lead Temperature (During Soldering, 1/16
1/32 in. (1.59
0.79mm) from case, 10s max)
+265
C
. . .
Circuit Operation
The master oscillator operates at 8 times the horizontal rate, fH, as determined by the external LC
connected between Pin5 and Pin6. The master oscillator is divided by 2, 4, and 8 and is then fed to
the horizontal output amplifier and also to a 10stage vertical countdown circuit. Horizontal AFC is
performed by comparing the horizontal ramp input signal on Pin2, derived from the flyback pulse, to
the horizontal sync signal on Pin3, producing correction voltage. The correction voltage then is ap-
plied to the master oscillator to phase lock the system.
The divide by 2 and 4 outputs are used to drive a 10stage counter for the vertical circuits. The use
of the countdown system and associated logic circuits assures good noise immunity and the deletion
of the vertical hold control.
Circuit Operation (Cont'd)
The Gain/Window switch input on Pin10 is a logic input which controls the digital window in which the
system looks for the occurrence of a vertical sync pulse: it also adjusts the phase detector gain for
the two corresponding vertical windows. The 464th (Pin10 = low) or the 512th (Pin10 = high) clock
pulse (at 2fH) from the horizontal divider is used to set the start of the vertical sync window. The end
of the sync window occurs at the 592nd (Pin10 = low) or the 568th (Pin10 = High) clock pulse. If the
incoming vertical sync pulse occurs regularly at the same time the 525th clock pulse occurs, it is used
to generate the start of the vertical blanking and vertical sweep; the system is in the standard sync
mode. If the incoming vertical sync pulse pulse is absent (removed by noise, for example), the
10stage counter will continue to provide an output pulse at the 525th clock pulse; a 3bit counter
will count the number of fields where no sync pulse occurred coincident with the 525th clock pulse.
If no coincidence is detected in 8 sequential fields, the 3bit counter energizes the toggle which shifts
the mode of operation from standard sync to nonstandard sync.
In the nonstandard sync mode vertical scan is initiated by the incoming vertical sync pulse. Non stan-
dard sync operation results when the incoming vertical sync pulse occurs regularly within the vertical
sync window; 464 to 592 counts (Pin10 = low) or 512 to 568 counts (Pin10 = high) but not at the 525th
count (Standard Sync Mode). In the nonstandard sync mode if no sync pulse is present, the system
will free run at a frequency determined by the 592 (Pin10 = low) or 568 (Pin10 = high) count.
The NTE1739 generates a composite blanking signal and a burstgate (key pulse) which, when
summed externally, produce the sandcastle pulse necessary for the operation of most Chrom/Lumi-
nance integrated circuits.
Electrical Characteristics: (T
A
= +25
to +70
C unless otherwise specified)
Parameter
Pin
Test Conditions
Min
Typ
Max
Unit
Supply Current
7
Adjust 24V Supply for 7V on Pin7
7
14
mA
Regulator Voltage
7
7.0
8.6
V
Saturation Voltages
Horizontal Output
8
0
0.4
V
Inverted Horizontal Output
13
0
0.4
V
Vertical Output
11
0
0.2
V
Blanking Output
12
0
0.175
V
Horizontal Ramp Output
15
0
0.175
V
Horizontal VCO Free Running Freq.
8
No Sync Applied S
1
= B
15547
15854
Hz
Horizontal VCO Oscillator PullIn
8
For 15734
1Hz
300
+300
Hz
Horizontal Blanking Width
12
Std NTSC Sync Applied
9.5
10.5
s
Vertical Blanking Width
12
Std NTSC Sync Applied
1140
1148
s
Burst Gate Width
16
Std NTSC Sync Applied
2.98
3.42
s
Burst Gate Delay
16
From End of Horizontal Sync (Pin3)
to Start of Burst Gate (Pin16)
20
215
ns
Horizontal Pulse Width
8
Std NTSC Sync Applied
31.4
32.1
s
Vertical Pulse Width
11
Std NTSC Sync Applied
504
516
s
Horizontal Sync Input
10
V
PP
Vertical Sync Input
10
V
PP
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