CXA1645 데이터 시트보기 (PDF) - Sony Semiconductor

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CXA1645

RGB Encoder

Sony Semiconductor 

CXA1645P/M

7. VREF pin (Pin 14)

Do not connect this pin to an external load that might cause AC signals to flow, which will cause IC

malfunctions. When connecting a DC load, make sure that the current flowing from this pin is kept below

2mA.

8. YTRAP pin (Pin 17)

There are the following two means of reducing cross color generated by subcarrier frequency components

contained in the Y signal.

(1) Install a capacitor of 30 to 68pF between YTRAP and GND. Decide the capacitance by conducting image

evaluation, etc., giving consideration to both cross color and resolution.

Relations between capacitance and image quality are as follows:

Capacitance

Cross color

Resolution

30pF ←→ 68pF

Large ←→ Small

High ←→ Low

17

C

(2) Connect a capacitor C and an inductor L in series between YTRAP and GND. When the subcarrier

frequency is fo, the values C and L are determined by the equation fo =

1

2π √LC

. Decide the values in

image evaluation, etc., giving consideration to both cross color and resolution.

Relations between inductor values and image quality are as follows:

Inductor value

Cross color

Resolution

Small ←→ Large

Large ←→ Small

High ←→ Low

17

C

L

For instance, L = 68µH and C = 28pF are recommended for NTSC. It is necessary to select an inductor L

with a sufficiently small DC resistance. Method (2) is more useful for achieving a higher resoluation than

method (1). When an even higher resolution is necessary, use of the S terminal (YOUT and COUT) is

recommended.

9. Driving COUT (Pin 15), YOUT (Pin 16), CVOUT (Pin 20), and B.G.R OUT (Pins 21, 22 and 23) outputs

In Pin Description, "Capable of driving a 75Ω load" means that the pin can drive a capacitor +75Ω +75Ω

load shown in the figure below. In other words, the pin is capable of driving a 150Ω load in AC.

75Ω 220µF

PIN

75Ω

Keep in mind that the pin is incapable of driving a 150Ω load in DC load in DC direct coupling.

10. This IC employs a number of 75Ω driver pins, so oscillation is likely to occur when measures described in

Nos. 4 and 6 are not taken thoroughly. Be very careful of oscillation in printed circuit board design and

carry out thorough investigations in the actual driving condition.

– 13 –

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