NTE1739 查看數據表（PDF） - NTE Electronics

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NTE1739

Integrated Circuit TV Horizontal/Vertical Countdown Digital Sync System

NTE Electronics 

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

10–stage counter will continue to provide an output pulse at the 525th clock pulse; a 3–bit 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 3–bit 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 burst–gate (key pulse) which, when

summed externally, produce the sandcastle pulse necessary for the operation of most Chrom/Lumi-

nance integrated circuits.

Electrical Characteristics: (TA = +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.

Horizontal VCO Oscillator Pull–In

8 No Sync Applied S1 = B

8 For 15734 ±1Hz

15547 – 15854 Hz

–300 – +300 Hz

Horizontal Blanking Width

12 Std NTSC Sync Applied

9.5

– 10.5 µs

Vertical Blanking Width

12 Std NTSC Sync Applied

1140 – 1148 µs

Burst Gate Width

16 Std NTSC Sync Applied

2.98 – 3.42 µs

Burst Gate Delay

16 From End of Horizontal Sync (Pin3) 20

to Start of Burst Gate (Pin16)

– 215 ns

Horizontal Pulse Width

8 Std NTSC Sync Applied

31.4 – 32.1 µs

Vertical Pulse Width

11 Std NTSC Sync Applied

504 – 516 µs

Horizontal Sync Input

–

Vertical Sync Input

–

–

10

– VP–P

–

10

– VP–P

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