REV. B

AD9883A

–15–

Table VI. Control Register Map

Write and

Hex

Read or

Default

Register

Address

Read Only

Bits

Value

Name

Function

00H

RO

7:0

Chip Revision

An 8-bit register that represents the silicon revision level.

Revision 0 = 0000 0000.

01H

*

R/

W

7:0

01101001

PLL Div MSB

This register is for Bits [11:4] of the PLL divider. Greater values mean

the PLL operates at a faster rate. This register should be loaded first

whenever a change is needed. This will give the PLL more time to lock.

02H

*

R/

W

7:4

1101

****

PLL Div LSB

Bits [7:4] of this word are written to the LSBs [3:0] of the

PLL divider word.

03H

R/

W

7:3

01

******

Bits [7:6] VCO Range. Selects VCO frequency range.

(See PLL description.)

**001***

Bits [5:3] Charge Pump Current. Varies the current that drives the

low-pass filter. (See PLL description.)

04H

R/

W

7:3

10000

***

Phase Adjust

ADC Clock Phase Adjustment. Larger values mean more delay.

(1 LSB = T/32)

05H

R/

W

7:0

10000000

Clamp

Places the Clamp signal an integer number of clock periods after the trail-

Placement

ing edge of the Hsync signal.

06H

R/

W

7:0

10000000

Clamp

Number of clock periods that the Clamp signal is actively clamping.

Duration

07H

R/

W

7:0

00100000

Hsync Output

Sets the number of pixel clocks that HSOUT will remain active.

Pulsewidth

08H

R/W

7:0

10000000

Red Gain

Controls ADC input range (contrast) of each respective channel.

Greater values give less contrast.

09H

R/W

7:0

10000000

Green Gain

0AH

R/W

7:0

10000000

Blue Gain

0BH

R/W

7:1

Red Offset

Controls dc offset (brightness) of each respective channel. Greater

values decrease brightness.

0CH

R/W

7:1

Green Offset

0DH

R/W

7:1

Blue Offset

0EH

R/

W

7:0

0

*******

Sync Control

Bit 7 – Hsync Polarity Override. (Logic 0 = Polarity determined by

chip, Logic 1 = Polarity set by Bit 6 in register 0EH.)

*1******

Bit 6 – Hsync Input Polarity. Indicates polarity of incoming Hsync

signal to the PLL. (Logic 0 = Active Low, Logic 1 = Active High.)

**0*****

Bit 5 – Hsync Output Polarity. (Logic 0 = Logic High Sync,

Logic 1 = Logic Low Sync.)

***0****

Bit 4 – Active Hsync Override. If set to Logic 1, the user can select

the Hsync to be used via Bit 3. If set to Logic 0, the active interface

is selected via Bit 6 in register 14H.

****0***

Bit 3 – Active Hsync Select. Logic 0 selects Hsync as the active

sync. Logic 1 selects Sync-on-Green as the active sync. Note that the

indicated Hsync will be used only if Bit 4 is set to Logic 1 or if both

syncs are active. (Bits 1, 7 = Logic 1 in register 14H.)

*****0**

Bit 2 – Vsync Output Invert. (Logic 1 = No Invert, Logic 0 = Invert.)

******0*

Bit 1 – Active Vsync Override. If set to Logic 1, the user can select

the Vsync to be used via Bit 0. If set to Logic 0, the active interface

is selected via Bit 3 in register 14H.

*******0

Bit 0 – Active Vsync Select. Logic 0 selects Raw Vsync as the output

Vsync. Logic 1 selects Sync Separated Vsync as the output Vsync.

Note that the indicated

Vsync will be used only if Bit 1 is set to Logic 1.

2-Wire Serial Register Map

The AD9883A is initialized and controlled by a set of registers,

which determine the operating modes. An external controller is

employed to write and read the control registers through the

two-line serial interface port.