LM1253AN National Semiconductor, LM1253AN Datasheet - Page 18

• Manufacturer Part Number: LM1253AN
• Description: Monolithic Triple 180 MHz I2C CRT Pre-amp With Integrated Analog On Screen Display (OSD) Generator
• Manufacturer: National Semiconductor

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BGAIN
GGAIN
RGAIN
CONTRAST
BBIAS
GBIAS
RBIAS
BRIGHTNESS
PEDESTAL
OSD
CONTRAST
DC OFFSET
Pre-Amp Functional Description
An active horizontal blanking signal is added to the video at
the output, giving excellent smear performance, and pre-
venting video content dependent DC bias offsets as a result
of high frequency over shoot.
Parameter
8438h Bits 7–5
8438h Bits 4–3
8438h Bits 2–0
Address
8430h
8431h
8432h
8433h
8434h
8435h
8436h
8437h
TABLE 2. Registers Controlling the Output Video and Clamp Signal
FIGURE 28. Register Control of the Output Video and Clamp Signal
Size
7 Bit
7 Bit
7 Bit
7 Bit
8 Bit
8 Bit
8 Bit
8 Bit
3 Bit
2 Bit
3 Bit
Blue Channel Gain
Green Channel Gain
Red Channel Gain
Overall Gain of All Three Channels
Blue Bias Clamp Pulse Amplitude
Green Bias Clamp Pulse Amplitude
Red Bias Clamp Pulse Amplitude
Amplitude of Brightness Clamp Pulse of All 3 Channels
Offset to the Brightness Control
OSD Gain
Active Video DC Offset of All 3 Channels
(Continued)
18
The outputs are referenced to a DC level (V
the LM1253A preamp, and so are guaranteed to provide
stable DC operating levels within the system without the
need for additional external feedback components.
Description
DS101265-31
REF
) produced by
Default
60h
60h
60h
60h
80h
80h
80h
80h
4h
2h
4h