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AD9948

HORIZONTAL CLAMPING AND BLANKING

The AD9948’s horizontal clamping and blanking pulses are

fully programmable to suit a variety of applications. Individual

sequences are defined for each signal, which are then organized

into multiple regions during image readout. This allows the dark

pixel clamping and blanking patterns to be changed at each

stage of the readout to accommodate different image transfer

timing and high speed line shifts.

Individual CLPOB and PBLK Sequences

The AFE horizontal timing consists of CLPOB and PBLK, as

shown in Figure 8. These two signals are independently pro-

grammed using the parameters shown in Table XII. The start

polarity, first toggle position, and second toggle position are

fully programmable for each signal. The CLPOB and PBLK

signals are active low, and should be programmed accordingly.

Up to four individual sequences can be created for each signal.

Individual HBLK Sequences

The HBLK programmable timing shown in Figure 9 is similar

to CLPOB and PBLK. However, there is no start polarity con-

trol. Only the toggle positions are used to designate the start and

the stop positions of the blanking period. Additionally, there is a

polarity control, HBLKMASK, which designates the polarity of

the horizontal clock signals H1–H4 during the blanking period.

Setting HBLKMASK high will set H1 = H3 = low and H2 =

H4 = high during the blanking, as shown in Figure 10. Up to

four individual sequences are available for HBLK.

(3)

(2)

(1)

CLPOB

PBLK

. . .

PROGRAMMABLE SETTINGS:

1. START POLARITY (CLAMP AND BLANK REGION ARE ACTIVE LOW)

2. FIRST TOGGLE POSITION

3. SECOND TOGGLE POSITION

ACTIVE

Figure 8. Clamp and Preblank Pulse Placement

(2)

(1)

HBLK

. . .

PROGRAMMABLE SETTINGS:

1. FIRST TOGGLE POSITION = START OF BLANKING

2. SECOND TOGGLE POSITION = END OF BLANKING

BLANK

Figure 9. Horizontal Blanking (HBLK) Pulse Placement

Table XII. CLPOB and PBLK Individual Sequence Parameters

Parameter

Length

Range

Description

Polarity

High/Low

Starting Polarity of Clamp and PBLK Pulses for Sequences 0–3.

Toggle Position 1

12b

0–4095 Pixel Location

First Toggle Position within the Line for Sequences 0–3.

Toggle Position 2

12b

0–4095 Pixel Location

Second Toggle Position within the Line for Sequences 0–3.

Table XIII. HBLK Individual Sequence Parameters

Parameter

Length

Range

Description

HBLKMASK

High/Low

Masking Polarity for H1 for Sequences 0–3 (0 = H1 Low, 1 = H1 High).

Toggle Position 1

12b

0–4095 Pixel Location

First Toggle Position within the Line for Sequences 0–3.

Toggle Position 2

12b

0–4095 Pixel Location

Second Toggle Position within the Line for Sequences 0–3.

Toggle Position 3

12b

0–4095 Pixel Location

Third Toggle Position within the Line for Sequences 0–3.

Toggle Position 4

12b

0–4095 Pixel Location

Fourth Toggle Position within the Line for Sequences 0–3.

Toggle Position 5

12b

0–4095 Pixel Location

Fifth Toggle Position within the Line for Sequences 0–3.

Toggle Position 6

12b

0–4095 Pixel Location

Sixth Toggle Position within the Line for Sequences 0–3.

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