adv7310 Analog Devices, Inc., adv7310 Datasheet - Page 47

• Manufacturer Part Number: adv7310
• Description: Multiformat 216 Mhz Video Encoder With Six Nsv 12-bit Dacs
• Manufacturer: Analog Devices, Inc.

PROGRAMMABLE DAC GAIN CONTROL
DACs A, B, and C are controlled by REG 0A.
DACs D, E, and F are controlled by REG 0B.
The I
down from its absolute level.
REV. A
CASE A
700mV
300mV
CASE B
700mV
300mV
GAIN PROGRAMMED IN DAC OUTPUT LEVEL
REGISTERS, SUBADDRESS 0Ah, 0Bh
2
Figure 40. Programmable DAC Gain—Positive and
Negative Gain
C control registers will adjust the output signal gain up or
NEGATIVE GAIN PROGRAMMED IN
DAC OUTPUT LEVEL REGISTERS,
SUBADDRESS 0Ah, 0Bh
–47–
In case A, the video output signal is gained. The absolute level
of the sync tip and blanking level both increase with respect to
the reference video output signal. The overall gain of the signal
is increased from the reference signal.
In case B, the video output signal is reduced. The absolute level
of the sync tip and blanking level both decrease with respect to
the reference video output signal. The overall gain of the signal
is reduced from the reference signal.
The range of this feature is specified for ± 7.5% of the nominal
output from the DACs. For example, if the output current of
the DAC is 4.33 mA, the DAC tune feature can change this
output current from 4.008 mA (–7.5%) to 4.658 mA (+7.5%).
The reset value of the vid_out_ctrl registers is 00h → nominal
DAC output current. The following table is an example of how
the output current of the DACs varies for a nominal 4.33 mA
output current.
Reg 0Ah or 0Bh
0100 0000 (40h)
0011 1111 (3Fh)
0011 1110 (3Eh)
...
...
0000 0010 (02h)
0000 0001 (01h)
0000 0000 (00h)
1111 1111 (FFh)
1111 1110 (FEh)
...
...
1100 0010 (C2h)
1100 0001 (C1h)
1100 0000 (C0h)
DAC
Current
(mA)
4.658
4.653
4.648
...
...
4.43
4.38
4.33
4.25
4.23
...
...
4.018
4.013
4.008
Table XI.
ADV7310/ADV7311
% Gain
7.5000%
7.3820%
7.3640%
...
...
0.0360%
0.0180%
0.0000%
–0.0180%
–0.0360%
...
...
–7.3640%
–7.3820%
–7.5000%
(I
Nominal)
2
C Reset Value,