adv7188 Analog Devices, Inc., adv7188 Datasheet - Page 19

• Manufacturer Part Number: adv7188
• Description: Multiformat Sdtv Video Decoder With Fast Switch Overlay Support
• Manufacturer: Analog Devices, Inc.

Fast Blank and Contrast Reduction
Programmable Thresholds
The internal fast blank and contrast reduction signals are
resolved from the trilevel FB signal using two comparators, as
shown in Figure 11. To facilitate compliance with different
input level standards, the reference level to these comparators is
programmable via FB_LEVEL [1:0] and CNTR_LEVEL [1:0].
The resulting thresholds are given in Table 15.
FB_LEVEL [1:0], Address 0xF1 [5:4]
These bits control the reference level for the fast blank comparator.
CNTR_LEVEL [1:0], Address 0xF1 [7:6]
These bits control the reference level for the contrast reduction
comparator.
Table 15. Fast Blank and Contrast Reduction Programmable Threshold I
CNTR_ENABLE
0
0
0
0
1
1
1
1
FB_LEVEL [1:0]
00 (default)
01
10
11
00 (default)
01
10
11
CNTR_LEVEL [1:0]
XX
XX
XX
XX
00
01
10
11
Rev. A | Page 19 of 112
Fast Blanking Threshold (V)
1.4
1.6
1.8
2.0
1.6
1.8
2.0
2.2
Figure 11. Fast Blank and Contrast Reduction Programmable Threshold
2
C Controls
PROGRAMMABLE
THRESHOLDS
FB PIN
Contrast Reduction Threshold (V)
n/a
n/a
n/a
n/a
0.4
0.6
0.8
2.0
FAST BLANK
COMPARATOR
CONTRAST
REDUCTION
COMPARATOR
+
–
–
+
FAST BLANK
C
ADV7188