Clamping; Figure 8: Video Signal Path To Adcs - Analog Devices Advantiv ADV7604 Hardware Manual

Function
REFERENCE_TRIM[2:0]
010
011
100
101
110
111
Important:
• The part must be set as follows when
Set AFE Map, register 0x0C to 0x1F
Set CP Map, register 0x3E[2] to 1b0
Set CP Map, register 0x40 to 0x60
• The default value of AFE Map, register 0x0C is 0x0E
• The default value of CP Map, register 0x3E is 0x80
• The default value of CP Map, register 0x40 is 0x80

6.2.3 Clamping

VOLTAGE_CLAMP_EN, IO Map, Address 0x30, [7]
The ADV7604 has three voltage clamps; one placed before each of the three ADCs (refer to
8). The purpose of the voltage clamp is to ensure that the video input signal lies inside the range of
the ADC. Clamping is done automatically and does not require user programming. Optimum
performance is selected by default.
analog input to scale the input video to the input range of the ADCs.
Resistor Divider
(24R/51R)
Pad
1V
Voltage
Clamp
Rev. F August 2010
Description
1.2 V
1.3 V
1.4 V (recommended setting)
Reserved
Reserved
Reserved
Figure 8 shows the resistor divider network required on each
0.9 SHA
Input Bu ffer
1V single-ended
SHA
x 1.4
CML

Figure 8: Video Signal Path to ADCs

REFERENCE_TRIM
CP Core Pre-Gain
Multiplier
ADC
0.75
REFP
1.2V
0.7V
ADC
REFERENCE_TRIM= 3b100
differential
0.5V
REFN
65
is set to 3b100:
CP Core
ADV7604
Figure