
37
TABLE 63. PROGRAMMABLE FRACTIONAL GAIN
SUB ADDRESS = 50
H
BIT
NO.
FUNCTION
DESCRIPTION
RESET
STATE
7-6
Reserved
Set to 00
B
for proper operation.
00
B
5
Select PFG Enable
Set to “1” to enable the recommended PFG value in bits 4-0 below.
0
B
(Use 1
B
)
4-0
PFG
Programmable Fractional Gain (PFG). When enabled by bit 5, changes the loop gain (response
time) of the AGC logic. Slower values provide some noise immunity to input signals with poor
sync/back-porch characteristics. Recommend using the slowest PFG value of 00001
B
for
optimum performance. (Thus the recommended 8-bit register value = 21
H
).
The 5-bit PFG value has a fractional representation as: 2
0
. 2
-1
2
-2
2
-3
2
-4
Sample PFG values:
00000
B
: Gain = 0.0000 (freezes AGC at current value)
00001
B
: Gain = 0.0625 (slowest AGC response time -- recommended PFG)
01100
B
: Gain = 0.7500 (default)
10000
B
: Gain = 1.0000
11111
B
: Gain = 1.9375 (fastest AGC response time -- not recommended)
01100
B
(Use 01
H
)
TABLE 64. MV STRIPE GATE
SUB ADDRESS = 51
H
BIT
NO.
FUNCTION
DESCRIPTION
RESET
STATE
7-6
Reserved
Set to 00
B
for proper operation.
00
B
5-0
MV Stripe Gate
Defines the start of the gate for MV Color Stripe detection in 4xF
SC
counts. The gate should start
prior to the chroma burst. Default value of 010100
B
(14
H
) is valid for NTSC. Recommend
100000
B
(20
H
) for PAL.
010100
B
TABLE 65. RESERVED
SUB ADDRESS = 52
H
BIT
NO.
FUNCTION
DESCRIPTION
RESET
STATE
7-0
Reserved
Set bit 5 to “1” for optimum performance.
02
H
(Use 22
H
)
TABLE 66. AGC HYSTERESIS
SUB ADDRESS = 53
H
BIT
NO.
FUNCTION
DESCRIPTION
RESET
STATE
7-4
Defines the amount of hysteresis in the AGC logic. Larger hysteresis values stabilize the AGC
with poor quality input signals. For example:
0000
B
= No Hysteresis
1000
B
= Default Hysteresis
1111
B
= Maximum Hysteresis (Recommended hysteresis value)
1000
B
(Use F0
H
)
3-0
Reserved
Set to 0000
B
for proper operation.
0000
B
TABLE 67. DEVICE REVISION
SUB ADDRESS = 7F
H
BIT
NO.
FUNCTION
DESCRIPTION
RESET
STATE
7-0
Device Revision
This 8-bit register specifies the device revision number. Data written to this read-only register is
ignored. The production baseline revision number is 01
H
.
01
H
HMP8117