adv7189b Analog Devices, Inc., adv7189b Datasheet - Page 31

• Manufacturer Part Number: adv7189b
• Description: Multiformat Sdtv Video Decoder
• Manufacturer: Analog Devices, Inc.

Table 33. AGC Modes
Input Video Type
Any
CVBS
Y/C
YPrPb
Luma Gain
LAGC[2:0] Luma Automatic Gain Control, Address
0x2C[7:0]
The luma automatic gain control mode bits select the mode of
operation for the gain control in the luma path. There are ADI
internal parameters to customize the peak white gain control.
Contact ADI sakes for more information.
Table 34. LAGC Function
LAGC[2:0]
000
001
010 (default)
011
100
101
110
111
LAGT[1:0] Luma Automatic Gain Timing, Address
0x2F[7:6]
The luma automatic gain timing register allows the user to
influence the tracking speed of the luminance automatic gain
control. Note this register only has an effect if the LAGC[2:0]
register is set to 001, 010, 011, or 100 (automatic gain control
modes).
If peak white AGC is enabled and active (see the
S TATUS_1[7:0] Address 0x10[7:0] section), the actual gain
1 8 9 H
update speed is dictated by the peak white AGC loop and, as a
result, the LAGT settings have no effect. As soon as the part
leaves peak white AGC, LAGT becomes relevant again.
The update speed for the peak white algorithm can be
customized by the use of internal parameters. Contact ADI
for more information.
Description
Manual fixed gain (use LMG[11:0])
AGC (blank level to sync tip); peak white
algorithm off
AGC (blank level to sync tip); peak white
algorithm on
Reserved
Reserved
Reserved
Reserved
Freeze gain
Luma Gain
Manual gain luma.
Dependent on horizontal sync depth.
Peak White.
Dependent on horizontal sync depth.
Peak White.
Dependent on horizontal sync depth.
Rev. B | Page 31 of 104
Table 35. LAGT Function
LAGT[1:0]
00
01
10
11 (default)
LG[11:0] Luma Gain, Address 0x2F[3:0]; Address
0x30[7:0]; LMG[11:0] Luma Manual Gain, Address
0x2F[3:0]; Address 0x30[7:0]
Luma Gain[11:0] is a dual-function register. If written to, a
desired manual luma gain can be programmed. This gain
becomes active if the LAGC[2:0] mode is switched to manual
fixed gain. Equation 1 shows how to calculate a desired gain. If
read back, this register returns the current gain value.
Depending on the setting in the LAGC[2:0] bits, this is one of
the following values:
x
x
Table 36. LG/LMG Function
LG[11:0]/LMG[11:0]
LMG[11:0] = X
LG[11:0]
Luma manual gain value (LAGC[2:0] set to luma manual
gain mode)
Luma automatic gain value (LAGC[2:0] set to any of the
automatic modes)
Luma
Chroma Gain
Manual gain chroma.
Dependent on color burst amplitude.
Taken from luma path.
Dependent on color burst amplitude.
Taken from luma path.
Dependent on color burst amplitude.
Taken from luma path.
Dependent on color burst amplitude.
Taken from luma path.
Taken from luma path.
_
Gain
0
Read/Write
Write
Read
LG
Description
Slow (TC = 2 sec)
Medium (TC = 1 sec)
Fast (TC = 0.2 sec)
Adaptive
2048
d
4095
Description
Manual gain for
luma path
Actually used gain
0
...
2
ADV7189B
(1)