LA7945N 查看數據表（PDF） - SANYO -> Panasonic

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LA7945N

Closed Caption Signal (US specifications) Extraction IC

SANYO -> Panasonic 

LA7945N

Pin Descriptions

Figure 1

* The peripheral circuit for the pins described below is shown in figure 1.

Either a resistor or a fixed current supply is connected to the lower side

(the side away from the pin) of the differential amplifier.

Pin 1 (21H OUT) : R=18kΩ. This signal goes high during the 21H and

284H periodes. The fall of this signal is taken as the completion of

data transfer.

Pin 2 (sync SEP) : R=9kΩ. Synchronization separation output, see pin

19.

Pin 3 (DATA OUT) : I≈280µA.

Outputs the data overlapped with the vertical retrace period.

Pin 5 (CLOCK OUT) : R=9kΩ. A clock output whose phase matches that

of DATA OUT.

Pin 6 (O/E OUT) : R=18kΩ. Field discrimination signal. High on odd

fields.

Pin 7 (H LOCK OUT) : I≈50µA.

A resistor and capacitor are connected to pin 8, and this pin goes

high when the internal VCO and the input signal are synchronized.

Pin 9 (V PULSE OUT) : R=18kΩ. Set low during the 0.5H period

synchronized with the vertical synchronization signal.

Pin 10 (H PULSE OUT) : R=18kΩ. Outputs a low signal synchronized

with the horizontal synchronization signal.

• Pin 8 (H LOCK FILTER) : The H LOCK detection filter is connected to this pin.

Pin 8 is charged when the H gate and Sync phases match, and this voltage

is compared and output to pin 7. The resistor R1 is used for discharge. The

time from internal VCO locking until pin 7 goes high, and the time from

lock release to the pin going low can be adjusted by changing the values of

C1 and R1. If the pin 7 H LOCK OUT output is not used, C1 and R1 will

be unnecessary.

Figure 2 : Pin 8 (H LOCK FILTER) Peripheral Circuit

• Pin 11 (VCO C) : The capacitor for the 32fH VCO is connected to this pin. (Error : 5%)

The LA7945N generates the 32fH oscillation not by using a ceramic resona-

tor, but by charging this capacitor with the fixed current defined by the resis-

tance connected at pin 12. The horizontal pulses and the clock output from

pin 5 are generated using this oscillator as a reference.

Figure 3 : Pin 11 (VCO C) Peripheral Circuit

No.4616–5/9

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