Analog Devices Advantiv ADV7604 Hardware Manual page 236

the full digitized waveform (including synchronizations) within the 12-bit output range. For this
application, the AGC_TAR[9:0] value is very important. For more information, refer to Section
10.4.
Note: The 12-bit target code for white is nominally 940, the target code for black is 64.
Examples:
An error signal is derived from the comparison of the measured synchronization depth and the
target value. The error signal is weighted by a factor that allows different response times to be
selected (AGC_TIM[2:0] is used to select different time constants). The resulting gain value is
applied to all three channels A, B, and C.
The AGC_FREEZE bit allows the AGC loop to be stopped, that is, frozen. If frozen, the currently
active gain is no longer updated but is applied continuously to all three data streams.
HS_NORM Nominal Horizontal Synchronization Depth Selection , CP Map, Address 0x71, [3]
Function
HS_NORM
0
1
AGC_TAR_MAN AGC Manual Target Level Enable , CP Map, Address 0x71, [5]
Function
AGC_TAR_MAN
0
1
AGC_TAR[9:0] AGC Manual Target Level , CP Map, Address 0x71, [7:6]; Address 0x72, [7:0]
Function
AGC_TAR[9:0]
xx xxxx xxxx
0x000
Rev. F August 2010
=
_ [ : 9 ] 0 (
AGC TAR Code
Equation 11: CP AGC Target Value
_
AGC TAR
=
286
HSync
_
AGC TAR
=
300
HSync
Description
AGC target is to scale the video as per 300 mV horizontal
synchronization depth
AGC target is to scale the video as per 286 mV horizontal
synchronization depth
Description
AGC operates based on a 300 mV or 286 mV horizontal synchronization
depth.
Use HS_NORM to select between the two.
AGC operates based on AGC_TAR[9:0].
Description
Sets the target value for the synchronization depth after gain has been
applied (feedback system). (Refer to
Default value
− •
)
Code
White Black
VideoHeigh
286
mV
= − •
( 940 64 )
mV
714
mV
300
mV
= − •
( 940 64 )
mV
700
mV
Equation
236
SyncHeight
mV
t
mV
=
351
dec
=
375
dec
11.)
ADV7604