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参数资料
| 型号： | LM1246AAA/NA |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 音频／视频放大 |
| 英文描述： | 3 CHANNEL, VIDEO PREAMPLIFIER, PDIP24 |
| 封装： | PLASTIC, DIP-24 |
| 文件页数： | 51/51页 |
| 文件大小： | 2794K |
| 代理商： | LM1246AAA/NA |
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Typical Performance Characteristics V
CC = 5V, TA = 25C unless otherwise specified (Continued)
SYSTEM INTERFACE SIGNALS
The Horizontal and Vertical Blanking and the Clamping input
signals are important for proper functionality of the LM1246.
Both blanking inputs must be present for OSD synchroniza-
tion. In addition, the Horizontal blanking input also assists in
setting the proper cathode black level, along with the Clamp-
ing pulse. The Vertical blanking input initiates a blanking
level at the LM1246 outputs which is programmable from 3
to 127 lines (we recommend at least 10). The start position
of the internal Horizontal blanking pulse is programmable
from 0 to 64 pixels ahead of the start position of the Hori-
zontal flyback input. Both horizontal and vertical blanking
can be individually disabled, if desired.
and Vertical inputs are logic levels. Figure 2 shows the
smaller pin 24 voltage superimposed on the horizontal
blanking pulse input to the neck board with R
H = 4.7k and
C
17 = 0.1 F. Note where the voltage at pin 24 is clamped to
about 1V when the pin is sinking current. Figure 3 shows the
smaller pin 1 voltage superimposed on the vertical blanking
input to the neck board with C
4 jumpered and RV = 4.7k.
These component values correspond to the application cir-
cuit of Figure 9.
Figures 4, 5 show the case where the horizontal and vertical
inputs are from deflection. Figure 4 shows the pin 24 voltage
which is derived from a horizontal flyback pulse of 35V peak
to peak with R
the pin 1 voltage which is derived from a vertical flyback
pulse of 55V peak to peak with C
4 = 1500 pF and RV = 120k.
Figure 6 shows the pin 23 clamp input voltage superimposed
on the neck board clamp logic input pulse. R
31 =1kand
should be chosen to limit the pin 23 voltage to about 2.5V
peak to peak. This corresponds to the application circuit
given in Figure 9.
CATHODE RESPONSE
Figure 7 shows the response at the red cathode for the
1.5 ns. The resulting leading edge has a 7.1 ns risetime and
a 7.6% overshoot, while the trailing edge has a 7.1 ns
risetime and a 6.9% overshoot with an LM2467 driver.
ABL GAIN REDUCTION
The ABL function reduces the contrast level of the LM1246
as the voltage on pin 22 is lowered from V
CC to around 2V.
Figure 8 shows the amount of gain reduction as the voltage
is lowered from V
CC (5.0V) to 2V. The gain reduction is small
until V
22 reaches the knee around 3.7V, where the slope
increases. Many system designs will require about 3 dB to
5 dB of gain reduction in full beam limiting. Additional attenu-
ation is possible, and can be used in special circumstances.
However, in this case, video performance such as video
linearity and tracking between channels will tend to depart
from normal specifications.
OSD PHASE LOCKED LOOP
The PLL in the LM1246 has a maximum pixels per line
setting significantly higher than that of the LM1247. The
range for the LM1246 is from 704 to 1152 pixels per line, in
increments of 64. The maximum OSD pixel frequency avail-
able is 111 MHz. For example, if the horizontal scan rate is
106kHz, 1024 pixels per line would be acceptable to use,
since the OSD pixel frequency is:
Horizontal Scan Rate X PPL =
106kHz X 1024 = 108.5 MHz
20068508
FIGURE 8. ABL Gain Reduction Curve
LM1246
www.national.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM1246AAC/NA | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述:IC 150MHZ RGB PREAMP 1246 DIP24 |
| LM1246AAC/NA/NOPB | 功能描述:IC PREAMP RGB 150MHZ 24-DIP RoHS:是 类别:集成电路 (IC) >> 线性 - 视频处理 系列:- 产品变化通告:Product Discontinuation 07/Mar/2011 标准包装:3,000 系列:OMNITUNE™ 类型:调谐器 应用:移动电话，手机，视频显示器 安装类型:表面贴装 封装/外壳:65-WFBGA 供应商设备封装:PG-WFSGA-65 包装:带卷 (TR) 其它名称:SP000365064 |
| LM1246NA | 制造商:NSC 制造商全称:National Semiconductor 功能描述:150 MHz I2C Compatible RGB Preamplifier with Internal 512 Character OSD ROM, 512 Character RAM and 4 DACs |
| LM1247 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:150 MHz I2C Compatible RGB Preamplifier with Internal 512 Character OSD ROM, 512 Character RAM and 4 DACs |
| LM1247AAG/NA | 功能描述:IC PREAMP CMOS 150MHZ 24DIP RoHS:否 类别:集成电路 (IC) >> 线性 - 视频处理 系列:- 产品变化通告:Product Discontinuation 07/Mar/2011 标准包装:3,000 系列:OMNITUNE™ 类型:调谐器 应用:移动电话，手机，视频显示器 安装类型:表面贴装 封装/外壳:65-WFBGA 供应商设备封装:PG-WFSGA-65 包装:带卷 (TR) 其它名称:SP000365064 |
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