Page 1
August 2000
LMC6772
Dual Micropower Rail-To-Rail Input CMOS Comparator
with Open Drain Output
LMC6772 Dual Micropower Rail-To-Rail Input CMOS Comparator with Open Drain Output
General Description
The LMC6772 is an ultra low power dual comparator with a
maximum 10 µA/comparator power supply current. It is designed to operate over a wide range of supply voltages, with
a minimum supply voltage of 2.7V.
The common mode voltage range of the LMC6772 exceeds
both the positive and negative supply rails, a significant advantage in single supply applications. The open drain output
of the LMC6772 allows for wired-OR configurations. The
open drain output also offers the advantage of allowing the
output to be pulled to any voltage rail up to 15V, regardless
of the supply voltage of the LMC6772.
The LMC6772 is targeted for systems where low power consumption is the critical parameter. Guaranteed operation at
supply voltages of 2.7V and rail-to-rail performance makes
this comparator ideal for battery-powered applications.
Refer to the LMC6762 datasheet for a push-pull output stage
version of this device.
Connection Diagram
8-Pin DIP/SO/MSOP
Features
(Typical unless otherwise noted)
n Low power consumption (max): I
n Wide range of supply voltages: 2.7V to 15V
n Rail-to-Rail Input Common Mode Voltage Range
n Open drain output
n Short circuit protection: 40 mA
n Propagation delay (
@
VS= 5V, 100 mV overdrive): 5 µs
= 10 µA/comp
S
Applications
n Laptop computers
n Mobile phones
n Metering systems
n Hand-held electronics
n RC timers
n Alarm and monitoring circuits
n Window comparators, multivibrators
DS012347-1
Top View
© 2000 National Semiconductor Corporation DS012347 www.national.com
Page 2
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
LMC6772
Distributors for availability and specifications.
ESD Tolerance (Note 2) 1.5 kV
Differential Input Voltage (V
Voltage at Input/Output Pin (V
+–V−
Supply Voltage (V
) 16V
Current at Input Pin (Note 8)
Current at Output Pin (Notes 3, 7)
+
)+0.3V to (V−)−0.3V
+
)+0.3V to (V−)−0.3V
±
5mA
±
30 mA
Storage Temperature Range −65˚C to +150˚C
Junction Temperature (Note 4) 150˚C
Operating Ratings (Note 1)
Supply Voltage 2.7 ≤ V
Junction Temperature Range
LMC6772AI, LMC6772BI 40˚C ≤ T
Thermal Resistance (θ
N Package, 8-Pin Molded DIP 100˚C/W
M Package, 8-Pin Surface Mount 172˚C/W
)
JA
Current at Power Supply Pin, LMC6772 40 mA
Lead Temperature (Soldering, 10 seconds) 260˚C
2.7V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ= 25˚C, V+= 2.7V, V−= 0V, VCM=V+/2. Boldface limits apply at the
temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
V
OS
TCV
OS
Input Offset Voltage 3 5 15 mV
Input Offset Voltage 2.0 µV/˚C
Temperature Drift
Input Offset Voltage (Note 10) 3.3 µV/Month
Average Drift
I
B
I
OS
Input Current 0.02 pA
Input Offset Current 0.01 pA
CMRR Common Mode Rejection Ratio 75 dB
PSRR Power Supply Rejection Ratio
A
V
V
CM
Voltage Gain (By Design) 100 dB
Input Common-Mode CMRR>55 dB 3.0 2.9 2.9 V
±
1.35V<V
<
±
7.5V 80 dB
S
Voltage Range 2.7 2.7 min
−0.3 −0.2 −0.2 V
V
OL
I
S
Output Voltage Low I
= 2.5 mA 0.2 0.3 0.3 V
LOAD
Supply Current For Both Comparators 12 20 20 µA
(Output Low) 25 25 max
I
Leakage
Output Leakage Current VIN(+) = 0.5V, 0.1 500 500 nA
V
(−) = 0V, VO= 15V
IN
LMC6772AI LMC6772BI Units
Limit Limit
(Note 6) (Note 6)
818max
0.0 0.0 max
0.4 0.4 max
≤ 15V
S
≤ +85˚C
J
5.0V and 15.0V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ= 25˚C, V+= 5.0V and 15.0V, V−= 0V, VCM=V+/2. Boldface limits
apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
V
OS
TCV
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Input Offset Voltage 3 5 15 mV
Input Offset Voltage V+= 5V 2.0 µV/˚C
OS
Temperature Drift V
Input Offset Voltage V
Average Drift V
+
= 15V 4.0
+
= 5V (Note 10) 3.3 µV/Month
+
= 15V (Note 10) 4.0
LMC6772AI LMC6772BI Units
Limit Limit
(Note 6) (Note 6)
818max
Page 3
5.0V and 15.0V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for TJ= 25˚C, V+= 5.0V and 15.0V, V−= 0V, VCM=V+/2. Boldface limits
apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
I
B
I
OS
CMRR Common Mode V
PSRR Power Supply Rejection Ratio
A
V
V
CM
Input Current V = 5V 0.04 pA
Input Offset Current V+= 5V 0.02 pA
+
=5V 75 dB
Rejection Ratio V
+
= 15V 82 dB
±
2.5V<V
<
±
5V 80 dB
S
Voltage Gain (By Design) 100 dB
Input Common-Mode V+= 5.0V 5.3 5.2 5.2 V
Voltage Range CMRR
>
55 dB 5.0 5.0 min
−0.3 −0.2 −0.2 V
+
V
= 15.0V 15.3 15.2 15.2 V
>
CMRR
55 dB 15.0 15.0 min
−0.3 −0.2 −0.2 V
V
OL
I
S
Output Voltage Low V+= 5V 0.2 0.4 0.4 V
I
=5mA 0.55 0.55 max
LOAD
+
V
= 15V 0.2 0.4 0.4 V
I
=5mA 0.55 0.55 max
LOAD
Supply Current For Both Comparators 12 20 20 µA
(Output Low) 25 25 max
I
SC
Short Circuit Current V+= 15V, Sinking, VO= 12V 45 mA
(Note 7)
LMC6772AI LMC6772BI Units
Limit Limit
(Note 6) (Note 6)
0.0 0.0 max
0.0 0.0 max
LMC6772
AC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ= 25˚C, V+= 5V, V−= 0V, VCM=VO=V+/2. Boldface limits apply at
the temperature extreme.
Symbol Parameter Conditions Typ
(Note 5)
t
RISE
Rise Time f = 10 kHz, CL= 50 pF, 0.3 µs
Overdrive = 10 mV (Note 9)
t
FALL
Fall Time f = 10 kHz, CL= 50 pF, 0.3 µs
Overdrive = 10 mV (Note 9)
t
PHL
Propagation Delay f = 10 kHz, 10 mV 10 µs
(High to Low) C
= 50 pF 100 mV 4 µs
L
(Note 9)
+
V
= 2.7V, 10 mV 10 µs
f = 10 kHz,
C
= 50 pF 100 mV 4 µs
L
(Note 9)
LMC6772AI LMC6772BI Units
Limit Limit
(Note 6) (Note 6)
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Page 4
AC Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for TJ= 25˚C, V+= 5V, V−= 0V, VCM=VO=V+/2. Boldface limits apply at
LMC6772
the temperature extreme.
Symbol Parameter Conditions Typ
(Note 5)
t
PLH
Propagation Delay f = 10 kHz, 10 mV 10 µs
(Low to High) C
= 50 pF 100 mV 4 µs
L
(Note 9)
+
V
= 2.7V, 10 mV 8 µs
f = 10 kHz,
C
= 50 pF 100 mV 4 µs
L
(Note 9)
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the devicemayoccur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the electrical characteristics.
Note 2: Human body model, 1.5 kΩ in series with 100 pF. The output pins of the two comparators (pin 1 and pin 7) have an ESD tolerance of 1.5 kV. All other pins
have an ESD tolerance of 2 kV.
Note 3: Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in exceeding the
maximum allowed junction temperature of 150˚C. Output currents in excess of
Note 4: The maximum power dissipation is a function of T
–TA)/θJA. All numbers apply for packages soldered directly into a PC board.
Note 5: Typical Values represent the most likely parametric norm.
Note 6: All limits are guaranteed by testing or statistical analysis.
Note 7: Do not short circuit output to V
Note 8: Limiting input pin current is only necessary for input voltages that exceed absolute maximum input voltage ratings.
Note 9: C
Note 10: Input offset voltage Average Drift is calculated by dividing the accelerated operating life drift average by the equivalent operational time. The input offset
voltage average drift represents the input offset voltage change at worst-case input conditions.
inlcudes the probe and jig capacitance. The rise time, fall time and propagation delays are measured with a 2V input step.
L
+
, when V+ is>12V or reliability will be adversely affected.
, θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD=(T
J(max)
±
30 mA over long term may adversely affect reliability.
LMC6772AI LMC6772BI Units
Limit Limit
(Note 6) (Note 6)
J(max)
Typical Performance Characteristics V
Supply Current vs Supply
Voltage (Output High)
DS012347-3
Supply Current vs Supply
Voltage (Output Low)
+
= 5V, Single Supply, TA= 25˚C unless otherwise specified
Input Current vs
Common-Mode Voltage
DS012347-4
DS012347-5
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Page 5
Typical Performance Characteristics V
specified (Continued)
+
= 5V, Single Supply, TA= 25˚C unless otherwise
LMC6772
Input Current vs
Common-Mode Voltage
∆VOSvs ∆V
CM
VS= 2.7V
DS012347-6
Input Current vs
Common-Mode Voltage
∆VOSvs ∆V
CM
VS=5V
DS012347-7
Input Current
vs Temperature
∆VOSvs ∆V
CM
VS= 15V
DS012347-8
Output Voltage vs
Output Current (Sinking)
DS012347-9
DS012347-12
Output Voltage vs
Output Current (Sinking)
DS012347-10
DS012347-13
DS012347-11
Output Voltage vs
Output Current (Sinking)
DS012347-14
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Page 6
Typical Performance Characteristics V
specified (Continued)
LMC6772
Output Short Circuit
Current (Sinking) vs
Supply Voltage
Leakage Current
vs Output Voltage
+
= 5V, Single Supply, TA= 25˚C unless otherwise
Response Time for
Overdrive (t
PLH
)
Response Time
for Overdrive (t
PHL
Response Time for
Overdrive (t
PLH
)
DS012347-15
Response Time
)
DS012347-18
for Overdrive (t
PLH
Response Time for
Overdrive (t
PHL
)
DS012347-16
Response Time
)
DS012347-19
for Overdrive (t
PHL
)
Response Time vs
Capacitive Load
DS012347-17
DS012347-20
DS012347-21
Application Hints
1.0 Input Common-Mode Voltage
Range
At supply voltages of 2.7V,5V and 15V,the LMC6772 has an
input common-mode voltage range which exceeds both supplies. As in the case of operational amplifiers, CMVR is defined by the V
common-mode range of the device. A CMRR (∆V
of 75 dB (typical) implies a shift of
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shift of the comparator over the
OS
<
1 mV over the entire
OS
/∆VCM)
DS012347-22
common-mode range of the device. The absolute maximum
input voltage at V
+
= 5V is 200 mV beyond either supply rail
DS012347-23
at room temperature.
Page 7
1.0 Input Common-Mode Voltage
Range
FIGURE 1. An Input Signal Exceeds the LMC6772
A wide input voltage range means that the comparator can
be used to sense signals close to ground and also to the
power supplies. This is an extremely useful feature in power
supply monitoring circuits.
An input common-mode voltage range that exceeds the supplies, 20 fA input currents (typical), and a high input impedance makes the LMC6772 ideal for sensor applications. The
LMC6772 can directly interface to sensors without the use of
amplifiers or bias circuits. In circuits with sensors which produce outputs in the tens to hundreds of millivolts, the
LMC6772 can compare the sensor signal with an appropriately small reference voltage. This reference voltage can be
close to ground or the positive supply rail.
(Continued)
DS012347-24
Power Supply Voltages with No Output Phase
Inversion
2.0 Low Voltage Operation
Comparators are the common devices by which analog signals interface with digital circuits. The LMC6772 has been
designed to operate at supply voltages of 2.7V, without sacrificing performance, to meet the demands of 3V digital systems.
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.
DS012347-25
FIGURE 2. Even at Low-Supply Voltage of 2.7V, an
Input Signal which Exceeds the Supply Voltages
Produces No Phase Inversion at the Output
+
At V
= 2.7V, propagation delays are t
4 µs with overdrives of 100 mV. Please refer to the performance curves for more extensive characterization.
= 4 µs and t
PLH
PHL
3.0 Output Short Circuit Current
The LMC6772 has short circuit protection of 40 mA. However,it is not designed to withstand continuous short circuits,
transient voltage or current spikes, or shorts to any voltage
beyond the supplies. A resistor is 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.
4.0 Hysteresis
If the input signal is very noisy, the comparator output might
trip several times as the input signal repeatedly passes
through the threshold. This problem can be addressed by
making use of hysteresis as shown below.
DS012347-26
FIGURE 3. Canceling the Effect of Input Capacitance
LMC6772
=
The capacitor added across the feedback resistor increases
the switching speed and provides more short term hysteresis. This can result in greater noise immunity for the circuit.
5.0 Spice Macromodel
A Spice Macromodel is available for the LMC6772. The
model includes a simulation of:
Input common-mode voltage range
•
Quiescent and dynamic supply current
•
Input overdrive characteristics
•
and many more characteristics as listed on the macromodel
disk.
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Page 8
5.0 Spice Macromodel (Continued)
Contact the National Semiconductor Customer Response
LMC6772
Center at 1-800-272-9959 to obtain an operational amplifier
spice model library disk.
Typical Applications
Universal Logic Level Shifter
The output of the LMC6772 is the uncommitted drain of the
output NMOS transistor. Many drains can be tied together to
provide an output OR’ing function. An output pullup resistor
can be connected to any available power supply voltage
within the permitted power supply range.
FIGURE 4. Universal Logic Level Shifter
DS012347-27
Bi-Stable Multivibrator
DS012347-30
FIGURE 6. Bi-Stable Multivibrator
Abi-stable multivibrator has two stable states. The reference
voltage is set up by the voltage divider of R
and R3. A pulse
2
applied to the SET terminal will switch the output of the comparator high. The resistor divider of R
, and R5now
1,R4
clamps the non-inverting input to a voltage greater than the
reference voltage. A pulse applied to RESET will now toggle
the output low.
Zero Crossing Detector
The two 1 kΩ resistors bias the input to half of the power
supply voltage. The pull-up resistor should go to the output
logic supply. Due to its wide operating range, the LMC6772
is ideal for the logic level shifting applications.
One-Shot Multivibrator
DS012347-28
FIGURE 5. One-Shot Multivibrator
A monostable multivibrator has one stable state in which it
can remain indefinitely. It can be triggered externally to another quasi-stable state. Amonostable multivibrator can thus
be used to generate a pulse of desired width.
The desired pulse width is set by adjusting the values of C
and R4. The resistor divider of R1and R2can be used to determine the magnitude of the input trigger pulse. The
LMC6772 will change state when V
vides a rapid discharge path for capacitor C
<
V2. Diode D2pro-
1
to reset at the
2
end of the pulse. The diode also prevents the non-inverting
input from being driven below ground.
DS012347-29
FIGURE 7. Zero Crossing Detector
A voltage divider of R
age V
at the non-inverting input. By making the series resis-
1
tance of R
when V
and R2equal to R5, the comparator will switch
1
= 0. Diode D1insures that V3never drops below
IN
−0.7V. The voltage divider of R
and R5establishes a reference volt-
4
and R3then prevents V
2
2
from going below ground. A small amount of hysteresis is
setup to ensure rapid output voltage transitions.
2
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Page 9
Typical Applications (Continued)
Oscillator
FIGURE 8. Square Wave Generator
Figure 8
wave generator circuit. The total hysteresis of the loop is set
by R
1,R2
discharge paths for the capacitor C. The charge path is set
through R
the RC time constant of R
path for the capacitor is set by R
between the pulses can be changed by varying R5, and the
pulse width can be altered by R
put can be changed by varying both R
DS012347-31
Time Delay Generator
shows the application of the LMC6772 in a square
and R3.R4and R5provide separate charge and
and D1. So, the pulse width t1is determined by
4
and C. Similarly, the discharge
4
and D2. Thus, the time t
5
. The frequency of the out-
4
and R5.
4
LMC6772
2
FIGURE 9. Time Delay Generator
The circuit shown above provides output signals at a prescribed time interval from a time reference and automatically
resets the output when the input returns to ground. Consider
the case of V
= 0. The output of comparator 4 is also at
IN
DS012347-32
ground. This implies that the outputs of comparators 1, 2,
and 3 are also at ground. When an input signal is applied,
the output of comparator 4 swings high and C charges exponentially through R. This is indicated above. The output volt-
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Page 10
Typical Applications (Continued)
ages of comparators 1, 2, and 3 swtich to the high state
LMC6772
when V
rises above the reference voltages VA,VBand VC.
C1
Ordering Information
Package Temperature Range NSC Drawing Transport
8-Pin Molded DIP LMC6772AIN, LMC6772BIN N08E Rails
8-Pin Small Outline LMC6772AIM, LMC6772BIM M08A Rails
LMC6772AIMX, LMC6772BIMX M08A Tape and Reel
8-Pin Mini SO LMC6772AIMM
LMC6772AIMMX
A small amount of hysteresis has been provided to insure
fast switching when the RC time constant is chosen to give
long delay times.
−40˚C to +85˚C Media
MUA08A Rails
Tape and Reel
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Page 11
Physical Dimensions inches (millimeters) unless otherwise noted
LMC6772
8-Pin Small Outline Package
Order Number LMC6772AI or LMC6772BI
NS Package Number M08A
8-Pin Molded Dual-In-Line Package
Order Number LMC6772AI or LMC6772BI
NS Package Number N08E
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Page 12
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
Order Number LMC6772AIMM or LMC6772AIMMX
NS Number MUA08A
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whose failure to perform when properly used in
accordance with instructions for use provided in the
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support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
labeling, can be reasonably expected to result in a
significant injury to the user.
LMC6772 Dual Micropower Rail-To-Rail Input CMOS Comparator with Open Drain Output
National Semiconductor
Corporation
Americas
Tel: 1-800-272-9959
Fax: 1-800-737-7018
Email: support@nsc.com
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