M52342 데이터 시트보기 (PDF) - MITSUBISHI ELECTRIC

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M52342

PLL-SPLIT VIF/SIF IC

MITSUBISHI ELECTRIC  

Pin 22 (VIDEO OUTPUT)

22

MITSUBISHI ICs (TV)

M52342FP

PLL-SPLIT VIF/SIF IC

An output amplitude is positive 2VP-P in the case of 87.5%

video modulation.

internal

driving current : 3mA

Pin 23 (APC FILTER)

Bias

12kΩ

1.1VO-P

In the locked state, the cut-off frequency of the filter is

adjusted effectively by an external resistor so that it will be

in the range of around 30 to 200kHz.

23

In case the cut-off frequency is lower, the pull-in speed

becomes slow. On the other hand, a higher cut-off frequency

widen the pull-in range and band width, which results

in a degradation in the S/N ratio. So, in the actual TV system

design, the appropriate constant should be chosen for getting

desirable performance considering above conditions.

[V23]

3.4VO-P

fo

[IF input frequency]

[Pin 23 output]

[FM mod. frequency]

100kHz

In the application, an offset between AFT center frequency and VCO free-running frequency, can be improved by connecting a 220kΩ resistor

to Vcc supply (pin 21).

23

21

220kΩ

C

A buzz noise also decreases by connecting a capacitor from

pin 23 to Vcc (pin 21) or GND. This effect utilizes the signal

interference on the printed circuit board. So, the determination

that which connection is effective, to Vcc or GND, is done by a

cut and try method.

The capacitor of less than 680pF, which depends on Q of VCO coil,

is recommended to prevent an APC pull-in range from narrowing.

Taking it into consideration in the actual TV set design.

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