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参数资料
| 型号： | LM1276AAA/NA |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 音频／视频放大 |
| 英文描述： | 1 CHANNEL, VIDEO PREAMPLIFIER, PDIP28 |
| 封装： | PLASTIC, DIP-28 |
| 文件页数： | 15/50页 |
| 文件大小： | 6075K |
| 代理商： | LM1276AAA/NA |
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OSD VIDEO TIMING
Please refer to the LM1247 datasheet for details.
CHARACTER CELL
Please refer to the LM1247 datasheet for details.
FOUR COLOR FONT AS TWO 2-COLOR
Please refer to the LM1247 datasheet for details.
ATTRIBUTE TABLES
Each character has an attribute value assigned to it in the
page RAM. The attribute value is 4 bits wide, making each
character entry in the page RAM 13 bits wide in total. The
attribute value acts as an address, which points to one of 16
entries in either the two-color attribute table RAM or the four-
color attribute table RAM. The attribute word in the table
contains the coding information which defines which color is
represented by color 0 and color 1 in the two color attribute
table and color 0, color 1, color 2, color 3 in the four-color
attribute table. Each color is defined by a 9-bit value, with 3
bits assigned to each channel of RGB. A dynamic look-up ta-
ble defines each of the 16 different color ‘palettes’. As the
look-up table can be dynamically coded by the microcontroller
over the I2C compatible interface, each color can be assigned
to any one of 29 (i.e. 512) choices. This allows a maximum of
64 different colors to be used within one page using the 4-
color characters, with up to 4 different colors within any one
character and 32 different colors using the 2-color characters,
with 2 different colors within any one character.
TRANSPARENT DISABLE
In addition to the 9 lines of video data, a tenth data line is
generated by the transparent disable bit. When this line is ac-
tivated, the black color code will be translated as ‘transparent’
or invisible. This allows the video information from the PC
system to be visible on the screen when this is present. Note
that this feature is enabled on any black color in any of the
first 8 attribute table entries.
VARIABLE TONE TRANSPARENCY
When the transparency is already in effect the tone of the
transparency can be adjusted. The contrast of the PC video
that is visible in the “transparent area” can be varied from
100% (fully transparent) to 0% (completely black). For exam-
ple, 50% reduction in contrast would provide a semi-trans-
parent effect. Just as in the conventional transparency mode,
variable tone transparency is effective on backgrounds or
foregrounds with black color codes from only the first 8 at-
tribute table entries. This feature is controlled by 0x85C0[6:0],
and is only available when the transparency mode is already
enabled.
OSD WINDOW FADE IN/FADE OUT
The OSD window can be opened and closed with a fade in/
fade out effect. The interval for fading in and fading out the
OSD window in the horizontal and vertical direction is variable
and can be set by the microcontroller. This allows the OSD
window to be opened or closed in the vertical directions, hor-
izontal direction, or from the upper left to lower right corner.
Assuming the desired time to typically complete a full fade in
or fade out is 0.5 seconds, and if the vertical scan frequency
is for example, 60 Hz, the number of steps is:
With a typical OSD window that is 300 pixels wide and 180
video lines long, the horizontal and vertical intervals would be:
For a smooth fade in or fade out animation from the upper left
corner to the lower right corner, the horizontal to vertical in-
terval ratio must be matched to the aspect ratio of the OSD
window. In the example above, the 300 pixel wide by 180 lines
long OSD window has an aspect ratio of 5:3. Thus, the hori-
zontal to vertical interval ratio should be set to 5/3 or 10/6.
With an OSD window aspect ratio of 3:2, the H/V intervals can
be set to 3/2, 6/4, 9/6, 12/8, or 15/10 for optimal operation. If
the calculated aspect ratio of an OSD window is a non-integer
ratio, the H/V interval ratio should meet or exceed the aspect
ratio. For example, if the OSD aspect ratio is 3.7:2 (or 1.85:1),
the H/V intervals should be set to 2/1, 4/2, 6/3, 8/4, 10/5, or
12/6. The fade in/out speed increases as H/V interval settings
are increased. The OSD window can also be faded in or out
in only one direction if desired, by setting the horizontal inter-
val to 0 for fading in/out strictly in the vertical direction or
setting the vertical interval to 0 for fading in/out in the hori-
zontal direction. In interlaced video formats, it is not recom-
mended to fade in and fade out the OSD in the vertical
direction, and should be only faded in the horizontal direction.
The fade in/out function can be enabled/disabled with bit 5 of
the frame control register, 0x8400, and the horizontal & ver-
tical intervals are controlled by setting register 0x8429. The
OSD window fade in/out feature can only be used with OSD
window 1.
ENHANCED FEATURES
Please refer to the LM1247 datasheet for details.
Microcontroller Interface
The microcontroller interfaces to the LM1276 preamp using
the I2C compatible interface. The protocol of the interface be-
gins with a Start Pulse followed by a byte comprised of a 7-
bit Slave Device Address and a Read/Write bit. Since the first
byte is composed of both the address and the read/write bit,
the address of the LM1276 for writing is 0xBA (10111010b)
and the address for reading is 0xBB (10111011b). The de-
velopment software provided by National Semiconductor will
automatically take care of the difference between the read
and write addresses if the target address under the commu-
nications tab is set to 0xBA. Figures 17, 18 show a write and
read sequence on the I2C compatible interface.
WRITE SEQUENCE
The write sequence begins with a start condition, which con-
sists of the master pulling SDA low while SCL is held high.
The Slave Device Write Address, 0xBA, is sent next. Each
byte that is sent is followed by an acknowledge bit. When SCL
is high, the master will release the SDA line. The slave must
pull SDA low to acknowledge. The register to be written to is
next sent in two bytes, the least significant byte being sent
first. The master can then send the data, which consists of
one or more bytes. Each data byte is followed by an acknowl-
edge bit. If more than one data byte is sent, the data will
increment to the next address location. See Figure 17.
www.national.com
22
200969 Version 2 Revision 4
Print Date/Time: 2011/07/11 11:20:12
LM1276
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM1279 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:110 MHz RGB Video Amplifier System with OSD |
| LM12791DL WAF | 制造商:Texas Instruments 功能描述: |
| LM1279A | 制造商:未知厂家 制造商全称:未知厂家 功能描述: |
| LM1279AN | 功能描述:IC AMP RGB VIDEO SYSTEM 20-DIP RoHS:否 类别:集成电路 (IC) >> 线性 - 放大器 - 视频放大器和频缓冲器 系列:- 标准包装:1,000 系列:- 应用:驱动器 输出类型:差分 电路数:3 -3db带宽:350MHz 转换速率:1000 V/µs 电流 - 电源:14.5mA 电流 - 输出 / 通道:60mA 电压 - 电源，单路/双路(±):5 V ~ 12 V，±2.5 V ~ 6 V 安装类型:表面贴装 封装/外壳:20-VFQFN 裸露焊盘 供应商设备封装:20-QFN 裸露焊盘（4x4） 包装:带卷 (TR) |
| LM1279DL WAF | 制造商:Texas Instruments 功能描述: |
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