Datasheet Texas Instruments LMC7211 (Texas Instruments) - 9

LMC7211-N www.ti.com
SNOS746F – MAY 2004 – REVISED JANUARY 2013
APPLICATION INFORMATION Benefits of the LMC7211 Tiny Comparator 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.
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 simplify board layout in several ways. First, by placing a comparator where comparators are needed, instead of routing signals to a dual or quad device, long pc traces may be avoided. By using multiple Tiny Comparators instead of duals or quads, complex signal routing and possibly crosstalk can be reduced.
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 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 useful 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 circuits. The small size of the Tiny package makes it easy to find space to add this feature to even compact designs.
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.
Zero Crossing Detector.
Since the LMC7211's common mode input range extends below ground even when powered by a single positive supply, it can be used with large input 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 circuits. 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.
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.
Low Voltage Operation
Comparators are the common devices by which analog signals interface with digital circuits. The LMC7211 has been designed to operate at supply voltages of 2.7V without sacrificing performance to meet the demands of 3V digital systems. Copyright © 2004–2013, Texas Instruments Incorporated Submit Documentation Feedback 9 Product Folder Links: LMC7211-N Document Outline FEATURES Applications DESCRIPTION Connection Diagram Absolute Maximum Ratings Operating Ratings 2.7V Electrical Characteristics 5.0V and 15.0V Electrical Characteristics AC Electrical Characteristics Typical Performance Characteristics Application Information Benefits of the LMC7211 Tiny Comparator Low Voltage Operation Shoot-Through Current Output Short Circuit Current Hysteresis Input Protection Layout Considerations Open Drain Output, Dual Versions Additional SOT23-5 Tiny Devices Spice Macromodel