LMC7221BIM5X National Semiconductor, LMC7221BIM5X Datasheet - Page 7

• Manufacturer Part Number: LMC7221BIM5X
• Description: IC,VOLT COMPARATOR,SINGLE,CMOS,SOP,8PIN,PLASTIC
• Manufacturer: National Semiconductor

Specifications of LMC7221BIM5X

• Rohs Compliant: NO

Typical Performance Characteristics
Application Information
1.0 BENEFITS OF THE LMC7221 TINY COMPARATOR
Size
The small footprint of the 5-Pin SOT23 packaged Tiny Com-
parator, (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 LMC7221 extends
battery life in portable applications, and may allow the reduc-
tion of the size of batteries in some applications.
Wide Voltage Range
The LMC7221 is characterized at 15V, 5V and 2.7V. Perfor-
mance data is provided at these popular voltages. This wide
voltage range makes the LMC7221 a good choice for de-
vices where the voltage may vary over the life of the batter-
ies.
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 micro-
processors and other digital circuits. The LMC7221 can be
thought of as a one-bit a/d converter.
Leakage Current vs. Supply Voltage
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Open Drain Output
The open drain output is like the open collector output of a
logic gate. This makes the LMC7221 very useful for mixed
voltage systems.
Driving LEDs (Light Emitting Diodes)
With a 5 volt power supply, the LMC7221’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 LMC7221 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, am-
plifiers, 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 LMC7221’s common mode input range extends
below ground even when powered by a single positive sup-
ply, it can be used with large input resistors as a zero
crossing detector.
Low Input Currents and High Input Impedance
These characteristics allow the LMC7221 to be used to
sense high impedance signals from sensors. They also
make it possible to use the LMC7221 in timing circuits built
with large value resistors. This can reduce the power dissi-
pation 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.
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