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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： | 2/51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)
TABLE 3. OSD Register Recommendations
PPL=0
PPL=1
PPL=2
PPL=3
PPL=4
PPL=5
PPL=6
PPL=7
PLL Auto
25 - 110
25 - 108
25 - 102
25 - 96
If 1152 pixels per line is being used, the horizontal scan rate
would have to be lower than 106 kHz in order to not exceed
the maximum OSD pixel frequency of 111 MHz. The maxi-
mum number of vertical video lines that may be used is 1536
lines as in a 2048x1536 display. The LM1246 has a PLL
Auto feature, which will automatically select an internal PLL
frequency range setting that will guarantee optimal OSD
locking for any horizontal scan rate. This offers improved
PLL performance and eliminates the need for PLL register
settings determined by the user. To initialize the PLL Auto
feature, set bits, 0x843E[1:0] to 0 for pre-calibration, which
takes one vertical scan period to complete, and must be
done while the video is blanked. Subsequently, set
0x843E[6] to 1, which must also be done while the video is
blanked. Table 3. OSD Register Recommendations shows
the recommended horizontal scan rate ranges (in kHz) for
each pixels per line register setting, 0x8401[7:5]. These
ranges are recommended for chip ambient temperatures of
0oCto70oC, and the recommended PLL filter values are
6.2kohms, 0.01uF, and 1000pF as shown in the schematic.
While the OSD PLL will lock for other register combinations
and at scan rates outside these ranges, the performance of
the loop will be improved if these recommendations are
followed.
PLL Auto Mode Initialization Sequence
Blank video
In PLL manual mode, set PLL range (0x843E[1:0]) to 0
Wait for at least one vertical period or vertical sync pulse
to pass
Set 0x843E[6] to 1 to activate the Auto mode
Wait for at least one vertical period or vertical sync pulse
to pass
Unblank video
This Sequence must be done by the microcontroller at sys-
tem power up, as well as each time there is a horizontal line
rate change from the video source, for the PLL Auto mode to
function properly.
Pin Descriptions and Application Information
Pin
No.
Pin Name
Schematic
Description
1
V Flyback
Required for OSD synchronization and is also
used for vertical blanking of the video outputs.
The actual switching threshold is about 35% of
V
CC. For logic level inputs C4 can be a jumper,
but for flyback inputs, an AC coupled
differentiator is recommended, where R
V is large
enough to prevent the voltage at pin 1 from
exceeding V
CC or going below GND. C4 should
be small enough to flatten the vertical rate ramp
at pin 1. C
24 may be needed to reduce noise.
2V
REF Bypass
Provides filtering for the internal voltage which
sets the internal bias current in conjunction with
R
EXT. A minimum of 0.1 F is recommended for
proper filtering. This capacitor should be placed
as close to pin 2 and the pin 4 ground return as
possible.
LM1246
www.national.com
10
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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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