AD9883A
Table VI. Control Register Map (continued)
Register
Write and
Read or
Read Only
Hex
Address
Default
Value
Bits
Name
Function
0FH
R/W
7:1
0*******
Bit 7 – Clamp Function. Chooses between Hsync for Clamp
signal or another external signal to be used for clamping.
(Logic 0 = Hsync, Logic 1 = Clamp.)
*1******
**0*****
Bit 6 – Clamp Polarity. Valid only with external Clamp signal.
(Logic 0 = Active High, Logic 1 Selects Active Low.)
Bit 5 – Coast Select. Logic 0 selects the coast input pins to be
used for the PLL coast. Logic 1 selects Vsync to be used for the
PLL coast.
***0****
****1***
*****1**
******1*
Bit 4 – Coast Polarity Override. (Logic 0 = Polarity determined by
chip, Logic 1 = Polarity set by Bit 3 in register 0FH.)
Bit 3 – Coast Polarity. Selects polarity of external Coast signal.
(Logic 0 = Active Low, Logic 1 = Active High.)
Bit 2 – Seek Mode Override. (Logic 1 = Allow Low Power Mode,
Logic 0 = Disallow Low Power Mode.)
Bit 1 – PWRDN. Full Chip Power-Down, Active Low. (Logic 0 =
Full Chip Power-Down, Logic 1 = Normal.)
10H
11H
R/W
R/W
7:3
7:0
10111***
*****0**
******0*
*******0
Sync-on-Green Sync-on-Green Threshold. Sets the voltage level of the Sync-on-
Threshold
Green slicer’s comparator.
Bit 2 – Red Clamp Select. Logic 0 selects clamp to ground.
Logic 1 selects clamp to midscale (voltage at Pin 37).
Bit 1 – Green Clamp Select. Logic 0 selects clamp to ground.
Logic 1 selects clamp to midscale (voltage at Pin 37).
Bit 0 – Blue Clamp Select. Logic 0 selects clamp to ground.
Logic 1 selects clamp to midscale (voltage at Pin 37).
00100000
Sync Separator
Threshold
Sync Separator Threshold. Sets how many internal 5 MHz clock
periods the sync separator will count to before toggling high or low.
This should be set to some number greater than the maximum
Hsync or equalization pulsewidth.
12H
13H
14H
R/W
R/W
RO
7:0
7:0
7:0
00000000
00000000
Pre-Coast
Pre-Coast. Sets the number of Hsync periods that Coast becomes
active prior to Vsync.
Post-Coast
Sync Detect
Post-Coast. Sets the number of Hsync periods that Coast stays
active following Vsync.
Bit 7 – Hsync detect. It is set to Logic 1 if Hsync is present on the
analog interface; otherwise it is set to Logic 0.
Bit 6 – AHS: Active Hsync. This bit indicates which analog Hsync
is being used. (Logic 0 = Hsync Input Pin, Logic 1 = Hsync from
Sync-on-Green.)
Bit 5 – Input Hsync Polarity Detect. (Logic 0 = Active Low,
Logic 1 = Active High.)
Bit 4 – Vsync Detect. It is set to Logic 1 if Vsync is present on the
analog interface; otherwise it is set to Logic 0.
Bit 3 – AVS: Active Vsync. This bit indicates which analog Vsync
is being used. (Logic 0 = Vsync Input Pin, Logic 1 = Vsync from
Sync Separator.)
Bit 2 – Output Vsync Polarity Detect. (Logic 0 = Active Low,
Logic 1 = Active High.)
Bit 1 – Sync-on-Green Detect. It is set to Logic 1 if sync is present
on the Green video input; otherwise it is set to 0.
Bit 0 – Input Coast Polarity Detect. (Logic 0 = Active Low, Logic 1 =
Active High.)
15H
R/W
7:0
1111****
****1***
*****1**
******1*
Test Register
Bits [7:4] Reserved for future use.
Bit 3 – Must be set to 1 for proper operation.
Bit 2 – Must be set to 1 for proper operation.
Bit 1 – 4:2:2 Output Formatting Mode (Logic 0 = 4:2:2 mode, Logic 1=
4:4:4 mode)
*******1
Bit 0 – Must be set to 0 for proper operation.
–16–
REV. B
ADI [ ADI ]
