NSC LMV7219M7X 7 nsec, 2.7v to 5v comparator with rail-to-rail output Datasheet

LMV7219
7 nsec, 2.7V to 5V Comparator with Rail-to-Rail Output
General Description
Features
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.
(VS = 5V, TA = 25˚C, Typical values unless specified)
n Propagation delay
7ns
n Low supply current
1.1mA
n Input common mode voltage range extends 200mv
below ground
n Ideal for 2.7V and 5V single supply applications
n Internal hysteresis ensures clean switching
n Fast rise and fall time
1.3ns
n Available in space-saving packages: 5-pin SC70-5 and
SOT23-5
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.
Applications
n
n
n
n
n
n
n
Portable and battery-powered systems
Scanners
Set top boxes
High speed differential line receiver
Window comparators
Zero-crossing detectors
High-speed sampling circuits
Typical Application
10105401
© 2004 National Semiconductor Corporation
DS101054
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LMV7219 7 nsec, 2.7V to 5V Comparator with Rail-to-Rail Output
November 2004
LMV7219
Connection Diagram
SC70-5/SOT23-5
10105402
Top View
Ordering Information
Package
5-pin SC70-5
5-pin SOT23-5
Part Number
Marking
Supplied as
LMV7219M7
C15
1k Units Tape and Reel
LMV7219M7X
C15
3k Units Tape and Reel
LMV7219M5
C14A
1k Units Tape and Reel
LMV7219M5X
C14A
3k Units Tape and Reel
NSC Drawing
MAA05A
MF05A
Simplified Schematic
10105403
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2
Voltage at Input/Output pins
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Current at Input Pin (Note 9)
ESD Tolerance (Note 2)
± 10mA
Operating Ratings
Machine Body
150V
Human Model Body
Supply voltages (V+ - V−)
2000V
Output Short Circuit Duration
(Note 3)
Supply Voltage (V+ - V−)
−40˚C to +85˚C
Storage Temperature Range
5.5V
−65˚C to +150˚C
Package Thermal Resistance
Soldering Information
Infrared or Convection (20
sec)
2.7V to 5V
Operating Temperature
Range (Note 4)
± Supply Voltage
Differential Input Voltage
Wave Soldering (10 sec)
(V+) + 0.4V
(V−) − 0.4V
235˚C
SC70-5
478˚C/W
SOT23-5
265˚C/W
260˚C (lead temp)
2.7V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VCM = V+/2, V+ = 2.7V, V− = 0V, CL = 10 pF and RL > 1 MΩ to
V−. Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Typ
(Note 5)
Limit
(Note 6)
Units
1
6
8
mV
max
VOS
Input Offset Voltage
IB
Input Bias Current
450
950
2000
nA
max
IOS
Input Offset Current
50
200
400
nA
max
CMRR
Common Mode Rejection Ratio
0V < VCM < 1.50V
85
62
55
dB
min
PSRR
Power Supply Rejection Ratio
V+ = 2.7V to 5V
85
65
55
dB
min
VCM
Input Common-Voltage Range
CMRR > 50 dB
VCC −1
VCC −1.2
VCC −1.3
V
min
−0.2
−0.1
0
V
max
IL = 4 mA,
VID = 500 mV
VCC −0.22
VCC −0.3
VCC −0.4
IL = 0.4 mA,
VID = 500 mV
VCC −0.02
VCC −0.05
VCC −0.15
IL = −4 mA,
VID = −500 mV
130
200
300
IL = −0.4 mA,
VID = −500 mV
15
50
150
Sourcing,
VO = 0V (Note 3)
20
Sinking,
VO = 2.7V (Note 3)
20
VO
Output Swing High
Output Swing Low
ISC
Output Short Circuit Current
V
min
mV
max
mA
IS
Supply Current
No Load
0.9
VHYST
Input Hysteresis Voltage
(Note 10)
7
VTRIP+
Input Referred Positive Trip Point
(see Figure 1)
3
8
mV
max
VTRIP−
Input Referred Negative Trip Point
(see Figure 1)
−4
−8
mV
min
3
1.6
2.2
mA
max
mV
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LMV7219
Absolute Maximum Ratings (Note 1)
LMV7219
2.7V Electrical Characteristics
(Continued)
Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VCM = V+/2, V+ = 2.7V, V− = 0V, CL = 10 pF and RL > 1 MΩ to
V−. Boldface limits apply at the temperature extremes.
Symbol
tPD
Parameter
Propagation Delay
Conditions
Typ
(Note 5)
Limit
(Note 6)
Units
Overdrive = 5 mV
VCM = 0V (Note 7)
12
Overdrive = 15 mV
VCM = 0V (Note 7)
11
Overdrive = 50 mV
VCM = 0V (Note 7)
10
1
ns
ns
max
20
tSKEW
Propagation Delay Skew
(Note 8)
tr
Output Rise Time
10% to 90%
2.5
ns
tf
Output Fall Time
90% to 10%
2
ns
5V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VCM = V+/2, V+ = 5V, V− = 0V, CL = 10 pF and RL > 1 MΩ to
V−. Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Typ
(Note 5)
Limit
(Note 6)
Units
1
6
8
mV
max
VOS
Input Offset Voltage
IB
Input Bias Current
500
950
2000
nA
max
IOS
Input Offset Current
50
200
400
nA
max
CMRR
Common Mode Rejection Ratio
0V < VCM < 3.8V
85
65
55
dB
min
PSRR
Power Supply Rejection Ratio
V+ = 2.7V to 5V
85
65
55
dB
min
VCM
Input Common-Mode Voltage Range
CMRR > 50 dB
VCC −1
VCC −1.2
VCC −1.3
V
min
−0.2
−0.1
0
V
max
IL = 4 mA,
VID = 500 mV
VCC −0.13
VCC −0.2
VCC −0.3
IL = 0.4 mA,
VID = 500 mV
VCC −0.02
VCC −0.05
VCC −0.15
IL = −4 mA,
VID = −500 mV
80
180
280
IL = −0.4 mA,
VID = −500 mV
10
50
150
Sourcing, VO = 0V
(Note 3)
68
30
20
Sinking, VO = 5V
(Note 3)
65
30
20
1.8
2.4
VO
Output Swing High
Output Swing Low
ISC
Output Short Circuit Current
V
min
mV
max
mA
min
IS
Supply Current
No Load
1.1
VHYST
Input Hysteresis Voltage
(Note 10)
7.5
VTrip+
Input Referred Positive Trip Point
(See figure 1)
3.5
8
mV
max
VTrip−
Input Referred Negative Trip Point
(See figure 1)
−4
−8
mV
min
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4
mA
max
mV
(Continued)
Unless otherwise specified, all limits guaranteed for TJ = 25˚C, VCM = V+/2, V+ = 5V, V− = 0V, CL = 10 pF and RL > 1 MΩ to
V−. Boldface limits apply at the temperature extremes.
Symbol
tPD
Parameter
Propagation Delay
Conditions
Typ
(Note 5)
Limit
(Note 6)
Units
ns
max
Overdrive = 5 mV
VCM = 0V (Note 7)
9
Overdrive = 15mV
VCM = 0V (Note 7)
8
20
Overdrive = 50 mV
VCM = 0V (Note 7)
7
19
tSKEW
Propagation Delay Skew
(Note 8)
tr
Output Rise Time
tf
Output Fall Time
0.4
ns
10% to 90%
1.3
ns
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 kΩ in series with 100 pF. Machine model, 200Ω in 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 = (TJ(MAX) - 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: 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.
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LMV7219
5V Electrical Characteristics
LMV7219
Typical Performance Characteristics
Unless otherwise specified, VS = 5V, CL = 10 pF, TA = 25˚C
VOS vs. Supply Voltage
Supply Current vs. Supply Voltage
10105404
10105405
Input Offset and Trip Voltage vs. Supply Voltage
Sourcing Current vs. Output Voltage
10105408
10105406
Sourcing Current vs. Output Voltage
Sinking Current vs. Output Voltage
10105409
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10105410
6
Propagation Delay vs. Temperature
(VS = 2.7V, VOD = 15 mV)
Sinking Current vs. Output Voltage
10105412
10105411
Propagation Delay vs. Capacitive Load
(VS = 5V, VOD = 15 mV)
Propagation Delay vs. Temperature
(VS = 5V, VOD = 15 mV)
10105413
10105414
Propagation Delay vs. Input Overdrive
Propagation Delay (tPD−)
10105416
10105415
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LMV7219
Typical Performance Characteristics Unless otherwise specified, VS = 5V, CL = 10 pF, TA =
25˚C (Continued)
LMV7219
Typical Performance Characteristics Unless otherwise specified, VS = 5V, CL = 10 pF, TA =
25˚C (Continued)
Propagation Delay (tPD+)
10105417
The LMV7219 has a push pull output. When the output
switches, there is a direct path between VCC 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 parasitic 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.
Application Section
LMV7219 is a single supply comparator with internal hysteresis, 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 Vcc. 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 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 comparatorinput 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
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8
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 comparator response time. Calculate the resistor values as follows:
1) Select R3. The current through R3 should be greater than
the input bias current to minimize errors. The current through
R3 (IF) at the trip point is (VREF - VOUT) /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:
(when VOUT = 0)
R3 = VREF/IF
(VOUT = VCC)
R3 = VCC - VREF /IF
2) Choose a hysteresis band required (VHB).
3) Calculate R1, where R1 = R3 X(VHB/VCC)
4) Choose the trip point for VIN rising. This is the threshold
voltage (VTHR) at which the comparator switches from low to
high as VIN rises about the trip point.
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 oscillations in the transition region. However, this capacitor can
cause some degradation to tpd when the source impedance
is low.
5) Calculate R2 as follows:
Zero-Crossing Detector
The inverting input is connected to ground and the noninverting input is connected to 100mVp-p signal. As the
signal at the non-inverting input crosses 0V, the comparator’s output Changes State.
6) Verify the trip voltage and hysteresis as follows:
10105422
FIGURE 3. Zero-Crossing Detector
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.
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 VREF threshold, the comparator’s output changes state.
10105421
FIGURE 2. Additional Hysteresis
Circuit Layout and Bypassing
10105423
The LMV7219 requires high-speed layout. Follow these layout guidelines:
1. Power supply bypassing is critical, and will improve stability and transient response. A decoupling capacitor such as
FIGURE 4. Threshold Detector
9
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LMV7219
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.
Additional Hysteresis
LMV7219
Crystal Oscillator
IR Receiver
A simple crystal oscillator using the LMV7219 is shown
below. Resistors R1 and R2 set the bias point at the comparator’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.
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.
10105425
FIGURE 6. IR Receiver
10105424
FIGURE 5. Crystal Oscillator
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10
LMV7219
Physical Dimensions
inches (millimeters) unless otherwise noted
5-Pin SC70-5
NS Package Number MAA05A
11
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LMV7219 7 nsec, 2.7V to 5V Comparator with Rail-to-Rail Output
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
5-Pin SOT23-5
NS Package Number MF05A
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the right at any time without notice to change said circuitry and specifications.
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