LM1276 National Semiconductor Corporation, LM1276 Datasheet - Page 38

• Manufacturer Part Number: LM1276
• Description: 150 Mhz I2c Compatible Rgb Preamplifier With Internal 512 Character Osd Rom, 512 Character Ram And 4 Dacs
• Manufacturer: National Semiconductor Corporation

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Pre-Amplifier Interface Registers
DAC 1 Output Level:
DAC 2 Output Level:
DAC 3 Output Level:
DAC 4 Output Level:
DAC Config, OSD Contrast & DC Offset:
Global Video Control:
Bits 6–0
Bit 7
Bits 7–0
Bits 7–0
Bits 7–0
Bits 7–0
Bits 2–0
Bits 5–3
Bit 6
Bit 7
This register determines the contrast gain and affects all three channels, blue, red and green.
Reserved and should be set to zero.
This register determines the output of DAC 1. The full-scale output is determined by bit 6 of the
DAC Config, OSD Contrast & DC Offset Register (0x8438).
This register determines the output of DAC 2. The full-scale output is determined by bit 6 of the
DAC Config, OSD Contrast & DC Offset Register (0x8438).
This register determines the output of DAC 3. The full-scale output is determined by bit 6 of the
DAC Config, OSD Contrast & DC Offset Register (0x8438).
This register determines the output of DAC 4. The output of this DAC can be scaled and mixed
with the outputs of DACs 1–3 as determined by bit 7 of the DAC Config, OSD Contrast & DC
Offset Register (0x8438).
These determine the DC offset of the three video outputs, blue, red and green.
These determine the contrast of the internally generated OSD.
When this bit is a 0, the full-scale outputs of DACs 1–3 are 0.5V to 4.5V. When it is a 1, the
full-scale range is 0.5V to 2.5V.
When this bit is a 0, the DAC 4 output is independent. When it is a 1, the DAC 4 output is scaled
by 50% and added to the outputs of DACs 1–3.
Contrast
Burn In
BI[1:0]
DAC Options
DCF[1:0]
Burn In
BI_EN PLLCAL
DACOSDDCOFF (0x8438)
GLOBALCTRL (0x8439)
OSD Contrast
DAC1CTRL (0x8434)
DAC2CTRL (0x8435)
DAC3CTRL (0x8436)
DAC4CTRL (0x8437)
DAC 1 Output Level
DAC 2 Output Level
DAC 3 Output Level
DAC 4 Output Level
OSD[2:0]
PLL
(Continued)
DAC1[7:0]
DAC2[7:0]
DAC3[7:0]
DAC4[7:0]
38
Res’d
RSV
Res’d
RSV
DC Offset
DC[2:0]
Power
PS
Blank
BV