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参数资料
| 型号： | LM1253AAE/NA |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 画面叠加 |
| 英文描述： | ON-SCREEN DISPLAY IC, PDIP28 |
| 封装： | 0.600 INCH, PLASTIC, DIP-28 |
| 文件页数： | 8/61页 |
| 文件大小： | 1671K |
| 代理商： | LM1253AAE/NA |
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National VideoPlex Video System
(Continued)
The response of the LM2453 CRT driver to the VideoPlex
signal from the LM1253A Pre-Amp is shown in
Figure 24.
Note that there are two sections in the video signal; the video
information is above V
REF and the clamp information is be-
low V
REF. The signals on the video out and clamp pins of the
LM2453 for an arbitrary video waveform from the LM1253A
is shown in
Figure 25.
ESD and Arc-Over Protection
The LM1253A incorporates full ESD protection with special
consideration given to maximizing arc-over robustness. The
monitor designer must still use good circuit design and PCB
layout techniques. The human body model ESD susceptibil-
ity of the LM1253A is 2 kV, however many monitor manufac-
turers are now testing their monitors to the level 4 of the IEC
801-2 specification which requires the monitor to survive an
8 kV discharge. External ESD protection is needed to sur-
vive this level of ESD. The LM1253A provides excellent
protection against both ESD and arc-over, but this is not a
substitute for good PCB layout.
Figure 26 show the recommended input protection for the
LM1253A. This provides the best protection against ESD.
When this protection is combined with good PCB layout the
LM1253A will easily survive the IEC 801-2 level 4 testing
(8 kV ESD). It is strongly recommended that the protection
diodes be added as shown in
Figure 26. The 1N4148 diode
has a maximum capacitance of 4 pF which will have little
effect on the response of the video system due to the low
impedance of the input video.
The ESD cells of the LM1253A also provide good protection
against arc-over, however good PCB layout is necessary.
The LM1253A should not be exposed directly to the voltages
that may occur during arc-over. The main vulnerability of the
LM1253A to arc-over is though the ground traces on the
PCB. For proper protection all ground connections associ-
ated with the LM1253A, including the grounds to the bypass
capacitors, must have short returns to the ground pins. A
significant ground plane should be used to connect all the
LM1253A grounds.
Figure 31, which shows the demo board
layout, is an excellent example of an effective ground plane.
The list below should be followed to ensure a PCB with good
grounding:
All grounds associated with the LM1253A should be con-
nected together through a large ground plane.
CRT driver ground is connected to the video pre-amp
ground at one point.
CRT and arc protection grounds are connected directly to
the chassis or main ground. There is no arc-over current
flow from these grounds through the LM1253A grounds.
Input signal traces for SDA, SCL, H Flyback, V Flyback,
Clamp should be kept away from the LM2453 and all
traces that an arc can travel on.
DS101265-27
FIGURE 24. DC I/O Transfer Characteristics for the LM2453 CRT Driver
(Test Conditions: V
REF = 1.65V, VCC1 = 80V, VBB = 8V)
DS101265-28
FIGURE 25. LM2453 Input and Output Waveforms
LM1253A
www.national.com
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM1253AN | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Monolithic Triple 180 MHz I2C CRT Pre-amp With Integrated Analog On Screen Display (OSD) Generator |
| LM-1256 | 制造商:ROHM 制造商全称:Rohm 功能描述:16 x 16 matrix displays |
| LM-1256_1 | 制造商:ROHM 制造商全称:Rohm 功能描述:16】16 matrix displays |
| LM-1256LB1 | 制造商:ROHM 制造商全称:Rohm 功能描述:16】16 matrix displays |
| LM125AN | 制造商:NSC 制造商全称:National Semiconductor 功能描述:VOLTAGE REGULATORS |
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