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RXM-418-LC-S 参数 Datasheet PDF下载

RXM-418-LC-S图片预览
型号: RXM-418-LC-S
PDF下载: 下载PDF文件 查看货源
内容描述: LC系列接收器模块数据 [LC SERIES RECEIVER MODULE DATA]
分类和应用:
文件页数/大小: 9 页 / 381 K
品牌: ETC [ ETC ]
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Basic Remote Control Receiver Circuit  
4. Observe appropriate layout practice between the module and its antenna. A  
simple trace may suffice for runs of less than 0.25" but longer distances should  
be covered using 50 coax or a 50 microstrip transmission line. This is  
because the trace leading to the module can effectively contribute to the length  
of the antenna, thus lowering its resonant bandwidth. In order to minimize loss  
and detuning, a microstrip transmission line is commonly utilized. The term  
microstrip refers to a PCB trace running over a groundplane, the width of  
which has been calculated to serve as a 50 transmission line between the  
module and antenna. This effectively removes the trace as a source of  
detuning.The correct trace width can be easily calculated using the information  
below.  
Figure 16 shows an  
example of a basic remote  
control receiver utilizing a  
decoder chip from Holtek.  
When a key is pressed at  
the transmitter, a corres-  
ponding pin at the receiver  
goes high. A schematic for  
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16  
15  
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NC  
ANT  
GND  
NC  
NC  
NC  
GND  
VCC  
PDN  
NC  
NC  
NC  
NC  
NC  
DATA  
NC  
the  
transmitter/encoder  
circuit may be found in  
the LC transmitter guide.  
These circuits can be  
easily modified and clearly  
demonstrate the ease of  
using the Linx LC modules  
for remote control appli-  
cations.  
HT658  
Figure 16: Basic Remote Control Receiver  
BOARD LAYOUT CONSIDERATIONS  
If you are at all familiar with RF devices you may be  
concerned about specialized board layout  
requirements. Fortunately, because of the care  
taken by Linx in designing the LC Series,  
integrating an LC-S receiver is very straightforward.  
This ease of application is a result of the advanced  
multi-layer isolated construction of the module. By  
adhering to good layout principles and observing a  
GROUNDPLANE  
ON LOWER LAYER  
Figure 17: Microstrip Formulas (Er = Dielectric constant of pc board material)  
few basic design rules you can enjoy  
straightforward path to RF success.  
a
1. No conductive items should be placed within 0.15  
in. of the module’s top or sides.  
Effective  
Dielectric Characteristic  
Constant  
3.59  
Always incorporate  
adequate groundplane  
Dielectric Width/Height  
2. A groundplane should be placed under the  
module as shown. In most cases, it will be placed  
Constant  
(W/d)  
1.8  
2
Impedance  
4.8  
50.0  
51.0  
on the bottom layer. The amount of overall plane area is also critical for the  
correct function of many antenna styles and is covered in the next section.  
4
3.07  
2.55  
3
2.12  
48.0  
3. Keep receiver module away from interference sources. Any frequency of  
sufficient amplitude to enter the receiver’s front end will reduce system range,  
cause bit errors, and may even prevent reception entirely. There are many  
possible sources of internally generated interference. High speed logic is one of  
the worst in this respect, as fast logic edges have harmonics which extend into  
the UHF band and the PCB tracks radiate these harmonics most efficiently.  
Microprocessors with external busses are generally incompatible with sensitive  
radio receivers. Single-chip microprocessors do not generally pose a problem.  
Switching power supplies, oscillators, even relays can also be significant  
sources of potential interference. Here again, the single best weapon against  
such problems is attention to placement and layout. Filter the supply with a high-  
frequency bypass capacitor as described above. Place adequate groundplane  
under all potential sources of noise.  
RECEIVER ANTENNA CONSIDERATIONS  
The choice of antennas is one of the most critical and often overlooked design  
considerations. The range, performance, and legality of an RF link is critically  
dependent upon the type of antenna employed. Proper design and matching of  
an antenna is a complex task requiring sophisticated test equipment and a  
strong background in principles of RF propagation. While adequate antenna  
performance can often be obtained by trial and error methods, you may also  
want to consider utilizing a professionally designed antenna such as those  
offered by Linx. Our low-cost antenna line is designed to ensure maximum  
performance and compliance with Part 15 attachment requirements.  
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