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 12 (VCO R) : The capacitor for the 32fH VCO is connected to this pin. (Error : 1%)

The resistor defines the current that charges the pin 11 capacitor. A DC volt-

age of 2/3 that of VCC is output from pin 12.

Figure 4 : Pin 12 (VCO R) Peripheral Circuit

• Pin 13 (AFC1) : The horizontal AFC filter is connected to this pin.

Although the ability to follow horizontal fluctuarions improves as R1 in-

creases, the holding power is reduced. Select this value according to the ap-

plication circuit. Since the closed caption signal is overlapped with 21H, the

VCO in this IC is influenced by signals such as the vertical synchronization

signal and the copy guard signal. The values of C2 and C3 should be deter-

mined so that the VCO is stable with respect to these signals. To stabilize pin

13 at a voltage of about 2.7V (when VCC=5V) with no input, the ratio of C2

and C3 should be set so that this voltage takes on a value close to the of pin

13 when power is first applied.

Figure 5 : Pin 13 (AFC1) Peripheral Circuit

No.4616–6/9

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