AD9995 Analog Devices, AD9995 Datasheet - Page 14

• Manufacturer Part Number: AD9995
• Description: 12-Bit CCD Signal Processor with Precision Timing Generator
• Manufacturer: Analog Devices

Generating Special HBLK Patterns
There are six toggle positions available for HBLK. Normally,
only two of the toggle positions are used to generate the standard
HBLK interval. However, the additional toggle positions may be
used to generate special HBLK patterns, as shown in Figure 12.
The pattern in this example uses all six toggle positions to gen-
erate two extra groups of pulses during the HBLK interval. By
changing the toggle positions, different patterns can be created.
AD9995
HBLK
H1/H3
THE POLARITY OF H1 DURING BLANKING IS PROGRAMMABLE (H2 IS OPPOSITE POLARITY OF H1).
HBLK
PROGRAMMABLE SETTINGS:
1. FIRST TOGGLE POSITION = START OF BLANKING
2. SECOND TOGGLE POSITION = END OF BLANKING
HD
HD
H1/H3
H2/H4
HBLK
H2/H4
H1/H3
1
BLANK
Figure 10. Horizontal Blanking (HBLK) Pulse Placement
TOG1
SPECIAL H-BLANK PATTERN IS CREATED USING MULTIPLE HBLK TOGGLE POSITIONS.
2
Figure 12. Generating Special HBLK Patterns
Figure 11. HBLK Masking Control
TOG2
TOG3
–14–
Generating HBLK Line Alternation
One further feature of the AD9995 is the ability to alternate dif-
ferent HBLK toggle positions on odd and even lines. This may be
used in conjunction with V-pattern odd/even alternation or on its
own. When a 1 is written to the HBLKALT register, TOG1 and
TOG2 are used on odd lines only, while TOG3–TOG6 are used
on even lines. Writing a 2 to the HBLKALT register gives the
opposite result: TOG1 and TOG2 are used on even lines, while
TOG3–TOG6 are used on odd lines. See the Vertical Timing
Generation, Line Alternation section for more information.
TOG4
TOG5
TOG6
BLANK
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