CXD1217 Просмотр технического описания (PDF) - Sony Semiconductor

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CXD1217

Synchronizing Signal Generator for Video Camera

Sony Semiconductor 

CXD1217Q

• V reset (VRI input)

When the VRI is input as shown in figure below, OSYNC can be reset at the same phase with the SYNC signal.

Counter State

1 2 3 4 5 67

SYNC Signal

VRI

CXD1217 internal clock (2fH)

(See Timing Chart Diagram)

V reset pulse

8 9 10 11 12 13 14 15

Falling edge permitted span

a

Rising edge is to be behind from point a

After reset SYNC OUT

9

10 11 12

13 14

Reset State

Since the falling edge point in the diagram above (marked with ↑) is the boundary of reset, if the falling edge

of the VRI input traverses that point, it causes 1/2H deviation to the reset state.

Accordingly, if resetting is applied between two similar systems whose frequency are different, the V to which

resetting is applied generates jitter of 1/2H. (When the resetting is applied continuously.)

• LALT reset (LALTRI input)

Phase relation between LALTRI pulse polarity and 2fH is the same as in the case of V resetting.

Resetting operation is basically required only in the external synchronizing mode (GEN LOCK mode). However,

even in the internal synchronizing mode, it sometimes requires H and V outputs whose phases are deviated

against a certain output. In that case, it suffices to use two CXD1217s and conduct the operation as follows:

Clock

CXD1217

OHD1 OVD1

VRI2

CXD1217

VRI2

OHD2 OVD2

Input

Shift Reg.

Clock

Output

Delay

∗ It suffices to set IC-1 and IC-2 into INT mode.

By varying the Delay and Shift Reg. of the above diagram, any phases of OHD2 and OVD2 can be provided

against the respective OHD1 and OVD1.

3. Color framing

In the case of internal synchronization in the individual NTSC, PAL and PALM systems, the phase

relationships between SYNC of the 1st field and sub-carrier are kept stable regardless of the power supply

being ON or OFF. However, as the PAL and PALM systems are comprised of PLL, the absolute values

concerning the phase according to variation of the ambient temperature drifts.

–6–

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