LMC7221AIM5X National Semiconductor, LMC7221AIM5X Datasheet - Page 9

• Manufacturer Part Number: LMC7221AIM5X
• Description: IC,VOLT COMPARATOR,SINGLE,CMOS,TSOP,5PIN,PLASTIC
• Manufacturer: National Semiconductor

Specifications of LMC7221AIM5X

• Rohs Compliant: NO

Application Information
4.0 OUTPUT SHORT CIRCUIT CURRENT
The LMC7221 has short circuit protection of 40 mA. How-
ever, it is not designed to withstand continuous short circuits,
transient voltage or current spikes, or shorts to any voltage
beyond the supplies. A resistor in series with the output
should reduce the effect of shorts. For outputs which send
signals off PC boards additional protection devices, such as
diodes to the supply rails, and varistors may be used.
5.0 INPUT PROTECTION
If input signals are likely to exceed the common mode range
of the LMC7221, or it is likely that signals may be present
when power is off, damage to the LMC7221 may occur.
Large value (100 kΩ to MΩ) input resistors may reduce the
likelihood of damage by limiting the input currents. Since the
LMC7221 has very low input leakage currents, the effect on
accuracy will be small. Additional protection may require the
use of diodes, as shown in Figure 3. Note that diode leakage
current may affect accuracy during normal operation.
The R-C time constant of R
also slow response time.
6.0 LAYOUT CONSIDERATIONS
The LMC7221 is not an especially fast comparator, so high
speed design practices are not required. The LMC7221 is
capable of operating with very high impedance inputs, so
precautions should be taken to reduce noise pickup with
high impedance (∼ 100 kΩ and greater) designs and in
electrically noisy environments.
Keeping high value resistors close to the LMC7221 and
minimizing the size of the input nodes is a good practice.
With multilayer designs, try to avoid long loops which could
act as inductors (coils). Sensors which are not close to the
comparator may need twisted pair or shielded connections
to reduce noise.
FIGURE 3.
IN
and the diode capacitance may
(Continued)
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7.0 PUSH-PULL OUTPUTS, DUAL VERSIONS
The LMC7211 is a comparator similar to the LMC7221, but
with push-pull outputs which can source current.
The performance of the LMC7221 is available in a dual
device. Please see the LMC6772 datasheet. For a dual
device with push-pull outputs, please see the LMC6762
datasheet.
Rail-to-Rail Input Low Power Comparators —
8.0 ADDITIONAL 5-Pin SOT23 TINY DEVICES
National Semiconductor has additional parts available in the
space saving SOT23 Tiny package, including amplifiers,
voltage references, and voltage regulators. These devices
include —
LMC7101 1 MHz gain-bandwidth rail-to-rail input and output
LMC7111 Low power 50 kHz gain-bandwidth rail-to-rail in-
LM7131
LP2980
LM4040
LM4041
LM385
Contact your National Semiconductor representative for the
latest information.
9.0 SPICE MACROMODEL
A Spice Macromodel is available for the LMC7221 compara-
tor on the National Semiconductor Amplifier Macromodel
disk. Contact your National Semiconductor representative to
obtain the latest version.
Push-Pull Output
LMC7221
LMC6762
Open Drain Output
LMC7221
LMC6772
amplifier — high input impedance and high gain
700 µA typical current 2.7V, 3V, 5V and 15V
specifications.
put and output amplifier with 25 µA typical current
specified at 2.7V, 3.0V, 3.3V, 5V and 10V.
Tiny Video amp with 70 MHz gain bandwidth 3V,
5V and
Micropower SOT 50 mA Ultra Low-Dropout
Regulator.
Precision micropower shunt voltage reference.
Fixed voltages of 2.500V, 4.096V, 5.000V, 8.192V
and 10.000V.
Precision micropower shut voltage reference
1.225V and adjustable.
Low current voltage reference. Fixed Voltages of
1.2V and 2.5V.
5-Pin SOT23, 8-Pin SOIC
8-Pin SOIC
5-Pin SOT23, 8-Pin SOIC
8-Pin SOIC
±
5V specifications.
Single
Dual
Single
Dual
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