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参数资料
| 型号： | LMH6580VSX |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 多路复用及模拟开关 |
| 英文描述： | 8-CHANNEL, CROSS POINT SWITCH, PQFP48 |
| 封装： | TQFP-48 |
| 文件页数： | 8/24页 |
| 文件大小： | 693K |
| 代理商： | LMH6580VSX |
Application Information
INTRODUCTION
The LMH6580/LMH6581 are high speed, fully buffered, non-
blocking, analog crosspoint switches. Having fully buffered
inputs allows the LMH6580/LMH6581 to accept signals from
low or high impedance sources without the worry of loading
the signal source. The fully buffered outputs will drive 75
or
50
back terminated transmission lines with no external com-
ponents other than the termination resistor. When disabled,
the outputs are in a high impedance state. The LMH6580/
LMH6581 can have any input connected to any (or all) output
(s). Conversely, a given output can have only one associated
input.
INPUT AND OUTPUT EXPANSION
The LMH6580/LMH6581 have high impedance inactive
states for both inputs and outputs allowing maximum flexibility
for crosspoint expansion. In addition the LMH6580/LMH6581
employ diagonal symmetry in pin assignments. The diagonal
symmetry makes it easy to use direct pin to pin vias when the
parts are mounted on opposite sides of a board. As an ex-
ample two LMH6580/LMH6581 chips can be combined on
one board to form either an 8 x 8 crosspoint or a 16 x 4 cross-
point. To make an 8 x 8 crosspoint all 8 input pins would be
tied together (Input 0 on side 1 to input 7 on side 2 and so on)
while the 4 output pins on each chip would be left separate.
To make the 16 x 4 crosspoint, the 4 outputs would be tied
together while all 16 inputs would remain independent. In the
16 x 4 configuration it is important not to have 2 connected
outputs active at the same time. With the 8 x 8 configuration,
on the other hand, having two connected inputs active is a
valid state. Crosspoint expansion as detailed above has the
advantage that the signal will go through only one crosspoint.
Expansion methods that have cascaded stages will suffer
bandwidth loss far greater than the small loading effect of
parallel expansion.
Output expansion as shown in Figure 1 is very straight for-
ward. Connecting the inputs of two crosspoint switches has a
very minor impact on performance. Input expansion requires
more planning. Input expansion, as show in Figure 2 and
Figure 3 gives the option of two ways to connect the outputs
of the crosspoint switches. In Figure 2 the crosspoint switch
outputs are connected directly together and share one termi-
nation resistor. This is the easiest configurarion to implement
and has only one drawback. Because the disabled output of
the unused crosspoint (only one output can be active at a
time) has a small amount of capacitance, the frequency re-
sponse of the active crosspoint will show peaking. This is
amount of peaking is not a problem.
As illustrated in Figure 3 each crosspoint output can be given
its own termination resistor. This results in a frequency re-
sponse nearly identical to the non expansion case. There is
one drawback for the gain of 2 crosspoint, and that is gain
error. With a 75
termination resistor the 1250 resistance
of the disabled crosspoint output will cause a gain error. In
order to counter act this the termination resistors of both
crosspoints should be adjusted to approximately 80
. This
will provide very good matching, but the gain accuracy of the
system will now be dependent on the process variations of
the crosspoint resistors which have a variability of approxi-
mately ±20%.
30007242
FIGURE 1. Output Expansion
30007243
FIGURE 2. Input Expansion with Shared Termination
Resistors
www.national.com
16
LMH6580/LMH6581
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LMH6581 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:8x4 500MHz Analog Crosspoint Switch, Gain of 1, Gain of 2 |
| LMH6581B E WAF | 制造商:Texas Instruments 功能描述: |
| LMH6581EVAL | 功能描述:BOARD EVALUATION FOR LMH6581 RoHS:否 类别:编程器，开发系统 >> 评估演示板和套件 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:- 主要目的:电源管理，电池充电器 嵌入式:否 已用 IC / 零件:MAX8903A 主要属性:1 芯锂离子电池 次要属性:状态 LED 已供物品:板 |
| LMH6581VS | 制造商:Texas Instruments 功能描述: |
| LMH6581VS/NOPB | 功能描述:IC CROSSPOINT SWITCH 8X4 48TQFP RoHS:是 类别:集成电路 (IC) >> 接口 - 模拟开关，多路复用器，多路分解器 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:2,500 系列:- 功能:- 电路:2 x SPST 导通状态电阻:20 欧姆 电压电源:单电源 电压 - 电源，单路/双路(±):3 V ~ 5.5 V 电流 - 电源:4.1mA 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:带卷 (TR) |
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