AD9923ABBCZ datasheet(34/88 Pages) AD

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AD9923A

Rev. 0 | Page 34 of 88

REGION 0

FIELD SETTINGS:

1. SEQUENCE CHANGE POSITIONS (SCP1 TO SCP8) DEFINE EACH OF THE NINE AVAILABLE REGIONS IN THE FIELD.

2. VSEQSEL0 TO VSEQSEL8 SELECTS THE DESIRED V-SEQUENCE FOR EACH REGION.

3. SGLINE1 REGISTER SELECTS WHICH HD LINE IN THE FIELD CONTAINS THE SENSOR-GATE PULSE(S).

XV1 TO XV13

SCP 1

SCP 2

VSEQSEL0

VSEQSEL1

SCP 3

VSEQSEL2

SCP 4

VSEQSEL3

SCP 5

VSEQSEL4

SCP 8

VSEQSEL8

REGION 1

REGION 2

REGION 3

REGION 4

REGION 8

VSG

SGACTLINE

SCP 0

Figure 46. Complete Field Is Divided into Regions

Second V-Pattern Group During VSG Active Line and

Special V-Pattern Insertion

Most CCDs require additional vertical timing during the sensor

gate line. The AD9923A can output a second V-pattern group

for XV1 to XV13 during the line when the VSG1 to VSG8

sensor gates are active. Figure 47 shows a typical VSG line,

which includes two sets of V-pattern groups for XV1 to XV13.

At the start of the VSG line, the V-pattern group is selected

using the appropriate VSEQSEL register. The second V-pattern

group, unique to the VSG line, is selected using the VPATSECOND

second VPAT group uses the VSTARTSECOND register. For

more information, see Table 16.

In addition to inserting a second V-pattern into the VSG line,

the AD9923A can insert a second V-pattern into any other

single line in each sequence. To enable this function in a par-

ticular sequence, set the SPXV_EN register in the appropriate

set of sequence registers to 1. The SPXV_ACT register determines

the active line for the special second V-pattern. The VPATSELB

and VSTARTB registers control both the V-pattern used and the

starting pixel location of the special second V-pattern. For more

information, see Table 17.

To avoid undesired behavior, do not use the special second

V-pattern in the VSG line; use the existing VPATSECOND and

VSTARTSECOND registers to insert a second V-pattern into

the VSG line. It is recommended that VPATSECOND and

VSTARTSECOND registers are used to create complex timing in

the sensor gate line and not the GROUPB registers. Additionally,

given that the special second V-pattern insertion uses some of the

Group B registers, the user cannot use the special second V-pattern

insertion function and Group B in the same sequence.

Table 17. Special Second V-Pattern Insertion

Length

(Bits)

Range

Description

SPXV_EN

0 or 1

0 = off, 1= enable special

second V-pattern insertion.

SPXV_ACT

Line 0 to

Line 4095

Active line for special

second V-pattern insertion.

VPATSELB

0 to 31

V-pattern

number

Selected V-pattern for

special second V-pattern

insertion if SPXV_EN = 1.

VSTARTB

0 to 8191

pixel

location

Start position for selected

V-pattern for special

second V-pattern

insertion if SPXV_EN = 1.

Sweep Mode Operation

The AD9923A contains an additional mode of vertical timing

operation called sweep mode. This mode is used to generate a

large number of repetitive pulses that span across multiple HD

lines. Normally, the vertical timing of the AD9923A must be

contained within one HD line length, but when sweep mode is

enabled, the HD boundaries are ignored until the region is

finished. This is useful, for example, in CCD readout operations.

Depending on the vertical resolution of the CCD, up to 3000 clock

cycles, spanning across several HD line lengths, can be required

to shift charge out of the vertical interline CCD registers. These

registers must be free of all charge at the end of the image

exposure before the image is transferred. This can be accom-

plished in sweep mode by quickly shifting out any charge using

a long series of pulses from the XV1 to XV13 outputs. To enable

sweep mode in any region, program the appropriate SWEEP

AD9923ABBCZ Datasheet(PDF) 34 Page - Analog Devices

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