LMV7219
7 nsec, 2.7V to 5V Comparator with Rail-to-Rail Output
General Description
The LMV7219 is a low-power, high-speed comparator with
internal hysteresis. The LMV7219 operating voltage ranges
from 2.7V to 5V with push/pull rail-to-rail output. This device
achieves a 7ns propagation delay while consuming only
1.1mA of supply current at 5V.
The LMV7219 inputs have a common mode voltage range
that extends 200mV below ground, allowing ground sensing.
The internal hysteresis ensures clean output transitions even
with slow-moving inputs signals.
The LMV7219 is available in the SC70-5 and SOT23-5
packages, which are ideal for systems where small size and
low power are critical.
Features
(V
S
=5V,T
A
= 25˚C, Typical values unless specified)
nPropagation delay 7ns
nLow supply current 1.1mA
nInput common mode voltage range extends 200mv
below ground
nIdeal for 2.7V and 5V single supply applications
nInternal hysteresis ensures clean switching
nFast rise and fall time 1.3ns
nAvailable in space-saving packages: 5-pin SC70-5 and
SOT23-5
Applications
nPortable and battery-powered systems
nScanners
nSet top boxes
nHigh speed differential line receiver
nWindow comparators
nZero-crossing detectors
nHigh-speed sampling circuits
Typical Application
10105401
November 2004
LMV7219 7 nsec, 2.7V to 5V Comparator with Rail-to-Rail Output
© 2004 National Semiconductor Corporation DS101054 www.national.com
Connection Diagram
SC70-5/SOT23-5
10105402
Top View
Ordering Information
Package Part Number Marking Supplied as NSC Drawing
5-pin SC70-5 LMV7219M7 C15 1k Units Tape and Reel MAA05A
LMV7219M7X C15 3k Units Tape and Reel
5-pin SOT23-5 LMV7219M5 C14A 1k Units Tape and Reel MF05A
LMV7219M5X C14A 3k Units Tape and Reel
Simplified Schematic
10105403
LMV7219
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Tolerance (Note 2)
Machine Body 150V
Human Model Body 2000V
Differential Input Voltage ±Supply Voltage
Output Short Circuit Duration (Note 3)
Supply Voltage (V
+
-V
−
) 5.5V
Soldering Information
Infrared or Convection (20
sec)
235˚C
Wave Soldering (10 sec) 260˚C (lead temp)
Voltage at Input/Output pins (V
+
) + 0.4V
(V
−
) − 0.4V
Current at Input Pin (Note 9) ±10mA
Operating Ratings
Supply voltages (V
+
-V
−
) 2.7V to 5V
Operating Temperature
Range (Note 4)
−40˚C to +85˚C
Storage Temperature Range −65˚C to +150˚C
Package Thermal Resistance
SC70-5 478˚C/W
SOT23-5 265˚C/W
2.7V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
CM
=V
+
/2, V
+
= 2.7V, V
−
= 0V, C
L
=10pFandR
L
>1MΩto
V
−
.Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
Limit
(Note 6)
Units
V
OS
Input Offset Voltage 1 6
8
mV
max
I
B
Input Bias Current 450 950
2000
nA
max
I
OS
Input Offset Current 50 200
400
nA
max
CMRR Common Mode Rejection Ratio 0V <V
CM
<1.50V 85 62
55
dB
min
PSRR Power Supply Rejection Ratio V
+
= 2.7V to 5V 85 65
55
dB
min
V
CM
Input Common-Voltage Range CMRR >50 dB V
CC
−1 V
CC
−1.2
V
CC
−1.3
V
min
−0.2 −0.1
0
V
max
V
O
Output Swing High I
L
= 4 mA,
V
ID
= 500 mV
V
CC
−0.22 V
CC
−0.3
V
CC
−0.4 V
min
I
L
= 0.4 mA,
V
ID
= 500 mV
V
CC
−0.02 V
CC
−0.05
V
CC
−0.15
Output Swing Low I
L
=−4mA,
V
ID
= −500 mV
130 200
300 mV
max
I
L
= −0.4 mA,
V
ID
= −500 mV
15 50
150
I
SC
Output Short Circuit Current Sourcing,
V
O
= 0V (Note 3)
20
mA
Sinking,
V
O
= 2.7V (Note 3)
20
I
S
Supply Current No Load 0.9 1.6
2.2
mA
max
V
HYST
Input Hysteresis Voltage (Note 10) 7 mV
V
TRIP
+Input Referred Positive Trip Point (see Figure 1)38mV
max
V
TRIP
−Input Referred Negative Trip Point (see Figure 1)−4−8mV
min
LMV7219
www.national.com3
2.7V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
CM
=V
+
/2, V
+
= 2.7V, V
−
= 0V, C
L
=10pFandR
L
>1MΩto
V
−
.Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
Limit
(Note 6)
Units
t
PD
Propagation Delay Overdrive=5mV
V
CM
= 0V (Note 7)
12
ns
max
Overdrive = 15 mV
V
CM
= 0V (Note 7)
11
Overdrive = 50 mV
V
CM
= 0V (Note 7)
10 20
t
SKEW
Propagation Delay Skew (Note 8) 1 ns
t
r
Output Rise Time 10% to 90% 2.5 ns
t
f
Output Fall Time 90% to 10% 2 ns
5V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
CM
=V
+
/2, V
+
= 5V, V
−
= 0V, C
L
=10pFandR
L
>1MΩto
V
−
.Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
Limit
(Note 6)
Units
V
OS
Input Offset Voltage 1 6
8
mV
max
I
B
Input Bias Current 500 950
2000
nA
max
I
OS
Input Offset Current 50 200
400
nA
max
CMRR Common Mode Rejection Ratio 0V <V
CM
<3.8V 85 65
55
dB
min
PSRR Power Supply Rejection Ratio V
+
= 2.7V to 5V 85 65
55
dB
min
V
CM
Input Common-Mode Voltage Range CMRR >50 dB V
CC
−1 V
CC
−1.2
V
CC
−1.3
V
min
−0.2 −0.1
0
V
max
V
O
Output Swing High I
L
= 4 mA,
V
ID
= 500 mV
V
CC
−0.13 V
CC
−0.2
V
CC
−0.3 V
min
I
L
= 0.4 mA,
V
ID
= 500 mV
V
CC
−0.02 V
CC
−0.05
V
CC
−0.15
Output Swing Low I
L
=−4mA,
V
ID
= −500 mV
80 180
280 mV
max
I
L
= −0.4 mA,
V
ID
= −500 mV
10 50
150
I
SC
Output Short Circuit Current Sourcing, V
O
=0V
(Note 3)
68 30
20 mA
min
Sinking, V
O
=5V
(Note 3)
65 30
20
I
S
Supply Current No Load 1.1 1.8
2.4
mA
max
V
HYST
Input Hysteresis Voltage (Note 10) 7.5 mV
V
Trip
+Input Referred Positive Trip Point (See figure 1) 3.5 8 mV
max
V
Trip
−Input Referred Negative Trip Point (See figure 1) −4 −8 mV
min
LMV7219
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5V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V
CM
=V
+
/2, V
+
= 5V, V
−
= 0V, C
L
=10pFandR
L
>1MΩto
V
−
.Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Typ
(Note 5)
Limit
(Note 6)
Units
t
PD
Propagation Delay Overdrive=5mV
V
CM
= 0V (Note 7)
9
ns
max
Overdrive = 15mV
V
CM
= 0V (Note 7)
820
Overdrive = 50 mV
V
CM
= 0V (Note 7)
719
t
SKEW
Propagation Delay Skew (Note 8) 0.4 ns
t
r
Output Rise Time 10% to 90% 1.3 ns
t
f
Output Fall Time 90% to 10% 1.25 ns
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. 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 kΩin series with 100 pF. Machine model, 200Ωin series with 100 pF.
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 ±30mA over long term may adversely affect reliability.
Note 4: The maximum power dissipation is a function of TJ(MAX),θJA, and TA. The maximum allowable power dissipation at any ambient temperature is
PD=(T
J(MAX) -T
A)/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: Propagation delay measurements made with 100 mV steps. Overdrive is measure relative to VTrip.
Note 8: Propagation Delay Skew is defined as absolute value of the difference between tPDLH and tPDHL.
Note 9: Limiting input pin current is only necessary for input voltages that exceed absolute maximum input voltage ratings.
Note 10: The LMV7219 comparator has internal hysteresis. The trip points are the input voltage needed to change the output state in each direction. The offset
voltage is defined as the average of Vtrip+and Vtrip−, while the hysteresis voltage is the difference of these two.
LMV7219
www.national.com5
Typical Performance Characteristics Unless otherwise specified, V
S
= 5V, C
L
= 10 pF, T
A
= 25˚C
Supply Current vs. Supply Voltage V
OS
vs. Supply Voltage
10105404 10105405
Input Offset and Trip Voltage vs. Supply Voltage Sourcing Current vs. Output Voltage
10105406 10105408
Sourcing Current vs. Output Voltage Sinking Current vs. Output Voltage
10105409 10105410
LMV7219
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Typical Performance Characteristics Unless otherwise specified, V
S
= 5V, C
L
= 10 pF, T
A
=
25˚C (Continued)
Sinking Current vs. Output Voltage
Propagation Delay vs. Temperature
(V
S
= 2.7V, V
OD
=15mV)
10105411 10105412
Propagation Delay vs. Temperature
(V
S
= 5V, V
OD
=15mV)
Propagation Delay vs. Capacitive Load
(V
S
= 5V, V
OD
=15mV)
10105413 10105414
Propagation Delay vs. Input Overdrive Propagation Delay (t
PD
−)
10105415
10105416
LMV7219
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Typical Performance Characteristics Unless otherwise specified, V
S
= 5V, C
L
= 10 pF, T
A
=
25˚C (Continued)
Propagation Delay (t
PD
+)
10105417
Application Section
LMV7219 is a single supply comparator with internal hyster-
esis, 7ns of propagation delay and only 1.1mA of supply
current.
The LMV7219 has a typical input common mode voltage
range of −0.2V below the ground to 1V below V
cc
. The
differential input stage is a pair of PNP transistors, therefore,
the input bias current flows out of the device. If either of the
input signals falls below the negative common mode limit,
the parasitic PN junction formed by the substrate and the
base of the PNP will turn on, resulting in an increase of input
bias current.
If one of the inputs goes above the positive common mode
limit, the output will still maintain the correct logic level as
long as the other input stays within the common mode range.
However, the propagation delay will increase. When both
inputs are outside the common mode voltage range, current
saturation occurs in the input stage, and the output becomes
unpredictable.
The propagation delay does not increase significantly with
large differential input voltages. However, large differential
voltages greater than the supply voltage should be avoided
to prevent damages to the input stage.
The LMV7219 has a push pull output. When the output
switches, there is a direct path between V
CC
and ground,
causing high output sinking or sourcing current during the
transition. After the transition, the output current decreases
and the supply current settles back to about 1.1mA at 5V,
thus conserving power consumption.
Most high-speed comparators oscillate when the voltage of
one of the inputs is close to or equal to the voltage on the
other input due to noise or undesirable feedback. The
LMV7219 have 7mV of internal hysteresis to counter para-
sitic effects and noise. The hysteresis does not change
significantly with the supply voltages and the common mode
input voltages as reflected in the specification table.
The internal hysteresis creates two trip points, one for the
rising input voltage and one for the falling input voltage. The
difference between the trip points is the hysteresis. With
internal hysteresis, when the comparator’s input voltages
are equal, the hysteresis effectively causes one comparator-
input voltage to move quickly past the other, thus taking the
input out of the region where oscillation occurs. Standard
comparators require hysteresis to be added with external
resistors. The fixed internal hysteresis eliminates these
resistors.
10105418
FIGURE 1. Input and Output Waveforms, Non-Inverting Input Varied
LMV7219
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Additional Hysteresis
If additional hysteresis is desired, this can be done with the
addition of three resistors using positive feedback, as shown
in Figure 2. The positive feedback method slows the com-
parator response time. Calculate the resistor values as fol-
lows:
1) Select R3. The current through R3 should be greater than
the input bias current to minimize errors. The current through
R3 (I
F
) at the trip point is (V
REF
-V
OUT
) /R3. Consider the two
possible output states when solving for R3, and use the
smaller of the two resulting resistor values. The two formulas
are:
R3=V
REF
/I
F
(when V
OUT
=0)
R3=V
CC
-V
REF
/I
F
(V
OUT
=V
CC
)
2) Choose a hysteresis band required (V
HB
).
3) Calculate R1, where R1 = R3 X(V
HB
/V
CC
)
4) Choose the trip point for V
IN
rising. This is the threshold
voltage (V
THR
) at which the comparator switches from low to
high as V
IN
rises about the trip point.
5) Calculate R2 as follows:
6) Verify the trip voltage and hysteresis as follows:
This method is recommended for additional hysteresis of up
to a few hundred millivolts. Beyond that, the impedance of
R3 is low enough to affect the bias string and adjustment of
R1 may be also required.
Circuit Layout and Bypassing
The LMV7219 requires high-speed layout. Follow these lay-
out guidelines:
1. Power supply bypassing is critical, and will improve sta-
bility and transient response. A decoupling capacitor such as
0.1µF ceramic should be placed as close as possible to V
+
pin. An additional 2.2µF tantalum capacitor may be required
for extra noise reduction.
2. Keep all leads short to reduce stray capacitance and lead
inductance. It will also minimize unwanted parasitic feedback
around the comparator.
3. The device should be soldered directly to the PC board
instead of using a socket.
4. Use a PC board with a good, unbroken low inductance
ground plane. Make sure ground paths are low-impedance,
especially were heavier currents are flowing.
5. Input traces should be kept away from output traces. This
can be achieved by running a topside ground plane between
the output and inputs.
6. Run the ground trace under the device up to the bypass
capacitor to shield the inputs from the outputs.
7. To prevent parasitic feedback when input signals are
slow-moving, a small capacitor of 1000pF or less can be
placed between the inputs. It can also help eliminate oscil-
lations in the transition region. However, this capacitor can
cause some degradation to tpd when the source impedance
is low.
Zero-Crossing Detector
The inverting input is connected to ground and the non-
inverting input is connected to 100mVp-p signal. As the
signal at the non-inverting input crosses 0V, the compara-
tor’s output Changes State.
Threshold Detector
Instead of tying the inverting input to 0V, the inverting input
can be tied to a reference voltage. The non-inverting input is
connected to the input. As the input passes the V
REF
thresh-
old, the comparator’s output changes state.
10105421
FIGURE 2. Additional Hysteresis
10105422
FIGURE 3. Zero-Crossing Detector
10105423
FIGURE 4. Threshold Detector
LMV7219
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Crystal Oscillator
A simple crystal oscillator using the LMV7219 is shown
below. Resistors R1 and R2 set the bias point at the com-
parator’s non-inverting input. Resistors R3, R4 and C1 sets
the inverting input node at an appropriate DC average level
based on the output. The crystal’s path provides resonant
positive feedback and stable oscillation occurs. The output
duty cycle for this circuit is roughly 50%, but it is affected by
resistor tolerances and to a lesser extent by the comparator
offset.
IR Receiver
The LMV7219 is an ideal candidate to be used as an infrared
receiver. The infrared photo diode creates a current relative
to the amount of infrared light present. The current creates a
voltage across RD. When this voltage level cross the voltage
applied by the voltage divider to the inverting input, the
output transitions.
10105424
FIGURE 5. Crystal Oscillator
10105425
FIGURE 6. IR Receiver
LMV7219
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Physical Dimensions inches (millimeters) unless otherwise noted
5-Pin SC70-5
NS Package Number MAA05A
LMV7219
www.national.com11
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
5-Pin SOT23-5
NS Package Number MF05A
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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(b) support or sustain life, and whose failure to perform when
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2. A critical component is any component of a life support
device or system whose failure to perform can be reasonably
expected to cause the failure of the life support device or
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LMV7219 7 nsec, 2.7V to 5V Comparator with Rail-to-Rail Output
