欢迎访问ic37.com |
会员登录 免费注册
发布采购

LMC7211BIM5X 参数 Datasheet PDF下载

LMC7211BIM5X图片预览
型号: LMC7211BIM5X
PDF下载: 下载PDF文件 查看货源
内容描述: 微型CMOS比较器具有轨至轨输入和推挽输出 [Tiny CMOS Comparator with Rail-to-Rail Input and Push-Pull Output]
分类和应用: 比较器放大器放大器电路光电二极管
文件页数/大小: 13 页 / 332 K
品牌: NSC [ National Semiconductor ]
 浏览型号LMC7211BIM5X的Datasheet PDF文件第3页浏览型号LMC7211BIM5X的Datasheet PDF文件第4页浏览型号LMC7211BIM5X的Datasheet PDF文件第5页浏览型号LMC7211BIM5X的Datasheet PDF文件第6页浏览型号LMC7211BIM5X的Datasheet PDF文件第8页浏览型号LMC7211BIM5X的Datasheet PDF文件第9页浏览型号LMC7211BIM5X的Datasheet PDF文件第10页浏览型号LMC7211BIM5X的Datasheet PDF文件第11页  
Application Information  
1.0 Benefits of the LMC7211 Tiny Comparator  
cuits. For very long timing circuits, using high value resistors  
can reduce the size and cost of large value capacitors for the  
same R-C time constant.  
Size. The small footprint of the SOT 23-5 packaged Tiny  
Comparator, (0.120 x 0.118 inches, 3.05 x 3.00 mm) saves  
space on printed circuit boards, and enable the design of  
smaller electronic products. Because they are easier to  
carry, many customers prefer smaller and lighter products.  
Direct Sensor Interfacing. The wide input voltage range  
and high impedance of the LMC7211 may make it possible  
to directly interface to a sensor without the use of amplifiers  
or bias circuits. In circuits with sensors which can produce  
outputs in the tens to hundreds of millivolts, the LMC7211  
can compare the sensor signal with an appropriately small  
reference voltage. This may be done close to ground or the  
positive supply rail. Direct sensor interfacing may eliminate  
the need for an amplifier for the sensor signal. Eliminating  
the amplifier can save cost, space, and design time.  
Height. The height (0.056 inches, 1.43 mm) of the Tiny  
Comparator makes it possible to use it in PCMCIA type III  
cards.  
Simplified Board Layout. The Tiny Comparator can sim-  
plify board layout in several ways. First, by placing a com-  
parator where comparators are needed, instead of routing  
signals to a dual or quad device, long pc traces may be  
avoided.  
2.0 Low Voltage Operation  
By using multiple Tiny Comparators instead of duals or  
quads, complex signal routing and possibly crosstalk can be  
reduced.  
Comparators are the common devices by which analog sig-  
nals interface with digital circuits. The LMC7211 has been  
designed to operate at supply voltages of 2.7V without sac-  
rificing performance to meet the demands of 3V digital sys-  
tems.  
Low Supply Current. The typical 7 µA supply current of the  
LMC7211 extends battery life in portable applications, and  
may allow the reduction of the size of batteries in some ap-  
plications.  
At supply voltages of 2.7V, the common-mode voltage range  
extends 200 mV (guaranteed) below the negative supply.  
This feature, in addition to the comparator being able to  
sense signals near the positive rail, is extremely useful in low  
voltage applications.  
Wide Voltage Range. The LMC7211 is characterized at  
15V, 5V and 2.7V. Performance data is provided at these  
popular voltages. This wide voltage range makes the  
LMC7211 a good choice for devices where the voltage may  
vary over the life of the batteries.  
Digital Outputs Representing Signal Level. Comparators  
provide a high or low digital output depending on the voltage  
levels of the (+) and (−) inputs. This makes comparators use-  
ful for interfacing analog signals to microprocessors and  
other digital circuits. The LMC7211 can be thought of as a  
one-bit a/d converter.  
Push-Pull Output. The push-pull output of the LMC7211 is  
capable of both sourcing and sinking milliamp level currents  
even at a 2.7 volt supply. This can allow the LMC7211 to  
drive multiple logic gates.  
Driving LEDs (Light Emitting Diodes). With a 5 volt power  
supply, the LMC7211’s output sinking current can drive  
small, high efficiency LEDs for indicator and test point cir-  
cuits. The small size of the Tiny package makes it easy to  
find space to add this feature to even compact designs.  
DS012337-5  
FIGURE 1. Even at Low-Supply Voltage of 2.7V, an  
Input Signal which Exceeds the Supply Voltages  
Produces No Phase Inversion at the Output  
Input range to Beyond Rail to Rail. The input common  
mode range of the LMC7211 is slightly larger than the actual  
power supply range. This wide input range means that the  
comparator can be used to sense signals close to the power  
supply rails. This wide input range can make design easier  
by eliminating voltage dividers, amplifiers, and other front  
end circuits previously used to match signals to the limited  
input range of earlier comparators. This is useful to power  
supply monitoring circuits which need to sense their own  
power supply, and compare it to a reference voltage which is  
close to the power supply voltage. The wide input range can  
also be useful for sensing the voltage drop across a current  
sense resistor for battery chargers.  
At V+ 2.7V propagation delays are tPLH 4 µs and tPHL  
4 µs with overdrives of 100 mV.  
=
=
=
Please refer to the performance curves for more extensive  
characterization.  
3.0 Shoot-Through Current  
The shoot-through current is defined as the current surge,  
above the quiescent supply current, between the positive  
and negative supplies of a device. The current surge occurs  
when the output of the device switches states. The  
shoot-through current results in glitches in the supply volt-  
ages. Usually, glitches in the supply lines are prevented by  
bypass capacitors. When the glitches are minimal, the value  
of the bypass capacitors can be reduced.  
Zero Crossing Detector. Since the LMC7211’s common  
mode input range extends below ground even when pow-  
ered by a single positive supply, it can be used with large in-  
put resistors as a zero crossing detector.  
Low Input Currents and High Input Impedance. These  
characteristics allow the LMC7211 to be used to sense high  
impedance signals from sensors. They also make it possible  
to use the LMC7211 in timing circuits built with large value  
resistors. This can reduce the power dissipation of timing cir-  
7
www.national.com