LM614
Quad Operational Amplifier and Adjustable Reference
General Description
Features
The LM614 consists of four op-amps and a programmable
voltage reference in a 16-pin package. The op-amp
out-performs most single-supply op-amps by providing
higher speed and bandwidth along with low supply current.
This device was specifically designed to lower cost and
board space requirements in transducer, test, measurement
and data acquisition systems.
Combining a stable voltage reference with four wide output
swing op-amps makes the LM614 ideal for single supply
transducers, signal conditioning and bridge driving where
large common-mode-signals are common. The voltage reference consists of a reliable band-gap design that maintains
low dynamic output impedance (1Ω typical), initial tolerance
(2.0%), and the ability to be programmed from 1.2V to 5.0V
via two external resistors. The voltage reference is very
stable even when driving large capacitive loads, as are
commonly encountered in CMOS data acquisition systems.
As a member of National’s new Super-Block™ family, the
LM614 is a space-saving monolithic alternative to a multichip
solution, offering a high level of integration without sacrificing
performance.
Op Amp
n Low operating current: 450µA
n Wide supply voltage range: 4V to 36V
n Wide common-mode range: V − to (V+− 1.8V)
n Wide differential input voltage: ± 36V
Reference
n Adjustable output voltage: 1.2V to 5.0V
n Initial tolerance: ± 2.0%
n Wide operating current range: 17µA to 20mA
n Tolerant of load capacitance
Applications
n
n
n
n
Transducer bridge driver and signal processing
Process and mass flow control systems
Power supply voltage monitor
Buffered voltage references for A/D’s
Connection Diagram
00932601
Ordering Information
Package
16-Pin Wide
Body SOIC
Temperature
Range
Part Number
Package Marking
Transport Media
NSC Drawing
0˚C to 70˚C
LM614CWM
LM614CWM
Rails
M16B
LM614CWMX
LM614CWM
1k Units Tape and Reel
LM614IWM
LM614IWM
Rails
LM614IWMX
LM614IWM
1k Units Tape and Reel
−40˚C to 85˚C
Super-Block™ is a trademark of National Semiconductor Corporation.
© 2001 National Semiconductor Corporation
DS009326
www.national.com
LM614 Quad Operational Amplifier and Adjustable Reference
December 2001
LM614
Absolute Maximum Ratings
(Note 1)
Storage Temperature Range
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Voltage on Any Pins except VR
(referred to V− pin)
(Note 2)
36V (Max)
(Note 3)
−0.3V (Min)
−65˚C ≤ TJ ≤ +150˚C
Maximum Junction Temperature
150˚C
Thermal Resistance,
Junction-to-Ambient (Note 4)
150˚C
Soldering Information (Soldering,
10 sec.)
220˚C
± 1kV
ESD Tolerance (Note 5)
Operating Temperature Range
Current through Any Input Pin &
± 20 mA
VR Pin
LM614C
0˚C ≤ TJ ≤ +70˚C
LM614C
± 36V
± 32V
LM614I
−40˚C ≤ TJ ≤ +85˚C
LM614I
Differential Input Voltage
Electrical Characteristics
These specifications apply for V− = GND = 0V, V+ = 5V, VCM = VOUT = 2.5V, IR = 100µA, FEEDBACK pin shorted to GND,
unless otherwise specified. Limits in standard typeface are for TJ = 25˚C; limits in Boldface type apply over the Operating
Temperature Range .
Symbol
IS
VS
Parameter
Conditions
Typ
(Note 6)
LM614I
LM614C
Limits
(Note 7)
Units
Total Supply
RLOAD = ∞,
450
1000
µA max
Current
4V ≤ V+ ≤ 36V (32V for LM614C)
550
1070
µA max
2.2
2.8
V min
Supply Voltage Range
2.9
3
V min
46
32
V max
43
32
V max
4V ≤ V+ ≤ 36V
1.5
5.0
mV max
(4V ≤ V+ ≤ 32V for LM614C)
2.0
7.0
mV max
V
1.0
5.0
mV max
1.5
7.0
mV max
OPERATIONAL AMPLIFIER
VOS1
VOS2
VOS Over Supply
VOS Over VCM
CM
(V
Average VOS Drift
+
= 0V through VCM =
− 1.8V), V+ = 30V
(Note 7)
µV/˚C
15
max
IB
IOS
Input Bias Current
Input Offset Current
Average Offset
Drift Current
10
35
nA max
11
40
nA max
0.2
4
nA max
0.3
5
nA max
4
pA/˚C
Differential
1800
MΩ
Common-Mode
RIN
Input Resistance
3800
MΩ
CIN
Input Capacitance
Common-Mode Input
5.7
pF
en
Voltage Noise
f = 100 Hz, Input Referred
74
In
Current Noise
f = 100 Hz, Input Referred
58
CMRR
Common-Mode
V
Rejection Ratio
CMRR = 20 log (∆VCM/∆VOS)
90
70
dB min
Power Supply
4V ≤ V+ ≤ 30V, VCM = V+/2,
110
75
dB min
Rejection Ratio
PSRR = 20 log (∆V+/∆VOS)
100
70
dB min
PSRR
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+
= 30V, 0V ≤ VCM ≤ (V+ − 1.8V),
2
95
75
dB min
(Continued)
These specifications apply for V− = GND = 0V, V+ = 5V, VCM = VOUT = 2.5V, IR = 100µA, FEEDBACK pin shorted to GND,
unless otherwise specified. Limits in standard typeface are for TJ = 25˚C; limits in Boldface type apply over the Operating
Temperature Range .
Symbol
AV
Parameter
Conditions
R
Voltage Gain
5V ≤ VOUT ≤ 25V
SR
Slew Rate
V
+
GBW
Gain Bandwidth
C
L
LM614I
LM614C
Limits
(Note 7)
Units
500
94
V/mV
50
40
min
± 0.70
± 0.65
± 0.50
± 0.45
V/µs
= 10 kΩ to GND, V+ = 30V,
Open Loop
L
Typ
(Note 6)
= 30V (Note 8)
= 50 pF
0.8
MHz
0.52
VO1
VO2
Output Voltage
R
Swing High
V
Output Voltage
R
L
+
L
+
= 10 kΩ to GND
V
= 36V (32V for LM614C)
V+ − 1.6
= 10 kΩ to V+
V
Swing Low
V
IOUT
Output Source
V
OUT
V
−IN
I SINK
Output Sink
V
OUT
Current
V
−IN
Short Circuit Current
V
OUT
V
−IN
ISHORT
+
−
− 1.4
+ 0.8
−
MHz
V
+
− 1.8
V min
V+ − 1.9
V min
V
−
+ 0.95
−
V max
= 36V (32V for LM614C)
V + 0.9
V + 1.0
V max
= 2.5V, V+IN = 0V,
25
16
mA min
= −0.3V
= 1.6V, V+IN = 0V,
= 0.3V
= 0V, V+IN = 3V,
= 2V, Source
V
OUT
V
−IN
= 5V, V+IN = 2V,
= 3V, Sink
15
13
mA min
17
13
mA min
9
8
mA min
30
50
mA max
40
60
mA max
30
70
mA max
32
90
mA max
VOLTAGE REFERENCE
VR
Voltage Reference
(Note 9)
1.244
1.2191
V min
1.2689
V max
( ± 2.0%)
Average Temperature
(Note 10)
10
150
Drift
max
Hysteresis
(Note 11)
3.2
V R Change
V R(100 µA) − VR(17 µA)
with Current
VR(10 mA) − VR(100 µA)
R
PPM/˚C
Resistance
µV/˚C
0.05
1
mV max
0.1
1.1
mV max
1.5
5
mV max
mV max
(Note 12)
2.0
5.5
∆V R(10→0.1 mA)/9.9 mA
0.2
0.56
Ω max
∆V R(100→17 µA)/83 µA
0.6
13
Ω max
V R Change
V R(Vro
with High VRO
(3.76V between Anode and
2.5
7
mV max
2.8
10
mV max
V
V R(V +
0.1
1.2
mV max
(V = 32V for LM614C)
0.1
1.3
mV max
VR(V +
0.01
1
mV max
0.01
1.5
mV max
22
50
nA max
29
55
nA max
= Vr)
− VR(Vro
= 5.0V)
FEEDBACK)
R
+
Change with
V Change
IFB
FEEDBACK Bias
= 5V)
− VR(V +
= 36V)
+
= 5V)
− VR(V +
= 3V)
V ANODE ≤ VFB ≤ 5.06V
Current
en
Voltage Noise
BW = 10 Hz to 10 kHz,
3
30
µV RMS
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LM614
Electrical Characteristics
LM614
Electrical Characteristics
(Continued)
These specifications apply for V− = GND = 0V, V+ = 5V, VCM = VOUT = 2.5V, IR = 100µA, FEEDBACK pin shorted to GND,
unless otherwise specified. Limits in standard typeface are for TJ = 25˚C; limits in Boldface type apply over the Operating
Temperature Range .
Symbol
Parameter
Conditions
Typ
(Note 6)
LM614I
LM614C
Limits
(Note 7)
Units
VRO = VR
Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the
device beyond its rated operating conditions.
Note 2: Input voltage above V+ is allowed.
Note 3: More accurately, it is excessive current flow, with resulting excess heating, that limits the voltages on all pins. When any pin is pulled a diode drop below
V−, a parasitic NPN transistor turns ON. No latch-up will occur as long as the current through that pin remains below the Maximum Rating. Operation is undefined
and unpredictable when any parasitic diode or transistor is conducting.
Note 4: Junction temperature may be calculated using TJ = TA + P DθjA. The given thermal resistance is worst-case for packages in sockets in still air. For packages
soldered to copper-clad board with dissipation from one comparator or reference output transistor, nominal θjA is 90˚C/W for the WM package.
Note 5: Human body model, 100 pF discharged through a 1.5 kΩ resistor.
Note 6: Typical values in standard typeface are for TJ = 25˚C; values in boldface type apply for the full operating temperature range. These values represent the
most likely parametric norm.
Note 7: All limits are guaranteed at room temperature (standard type face) or at operating temperature extremes (bold type face).
Note 8: Slew rate is measured with op amp in a voltage follower configuration. For rising slew rate, the input voltage is driven from 5V to 25V, and the output voltage
transition is sampled at 10V and @20V. For falling slew rate, the input voltage is driven from 25V to 5V, and the output voltage transition is sampled at 20V and 10V.
Note 9: VR is the Cathode-feedback voltage, nominally 1.244V.
Note 10: Average reference drift is calculated from the measurement of the reference voltage at 25˚C and at the temperature extremes. The drift, in ppm/˚C, is
106 • ∆V R/(VR[25˚C] • ∆TJ), where ∆V R is the lowest value subtracted from the highest, VR[25˚C] is the value at 25˚C, and ∆TJ is the temperature range. This parameter
is guaranteed by design and sample testing.
Note 11: Hysteresis is the change in VR caused by a change in TJ, after the reference has been “dehysterized”. To dehysterize the reference; that is minimize the
hysteresis to the typical value, cycle its junction temperature in the following pattern, spiraling in toward 25˚C: 25˚C, 85˚C, −40˚C, 70˚C, 0˚C, 25˚C.
Note 12: Low contact resistance is required for accurate measurement.
Typical Performance Characteristics (Reference)
TJ = 25˚C, FEEDBACK pin shorted to V−
= 0V, unless otherwise noted
Reference Voltage vs.
Temperature on 5 Representative Units
Reference Voltage Drift
00932648
00932647
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4
TJ = 25˚C, FEEDBACK pin shorted to V−
= 0V, unless otherwise noted (Continued)
Accelerated Reference Voltage Drift vs. Time
Reference Voltage vs. Current and Temperature
00932649
00932650
Reference Voltage vs. Current and Temperature
Reference Voltage vs. Reference Current
00932652
00932651
Reference Voltage vs. Reference Current
Reference AC Stability Range
00932653
00932654
5
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LM614
Typical Performance Characteristics (Reference)
LM614
Typical Performance Characteristics (Reference)
TJ = 25˚C, FEEDBACK pin shorted to V−
= 0V, unless otherwise noted (Continued)
FEEDBACK Current vs. FEEDBACK-to-Anode Voltage
FEEDBACK Current vs. FEEDBACK-to-Anode Voltage
00932655
00932656
Reference Noise Voltage vs. Frequency
Reference Small-Signal Resistance vs. Frequency
00932657
00932658
Reference Power-Up Time
Reference Voltage with FEEDBACK Voltage Step
00932659
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00932660
6
TJ = 25˚C, FEEDBACK pin shorted to V−
= 0V, unless otherwise noted (Continued)
Reference Step Response for 100 µA ∼ 10 mA Current
Step
Reference Voltage with 100∼12 µA Current Step
00932661
00932662
Reference Voltage Change with Supply Voltage Step
00932663
Typical Performance Characteristics (Op Amps)
V+ = 5V, V− = GND = 0V, VCM = V+/2,
VOUT = V+/2, TJ = 25˚C, unless otherwise noted
VOS vs. Junction Temperature on 9 Representative Units
Input Common-Mode Voltage Range vs. Temperature
00932665
00932664
7
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LM614
Typical Performance Characteristics (Reference)
LM614
Typical Performance Characteristics (Op Amps)
V+ = 5V, V− = GND = 0V, VCM = V+/2,
+
VOUT = V /2, TJ = 25˚C, unless otherwise noted (Continued)
Input Bias Current vs. Common-Mode Voltage
Slew Rate vs. Temperature and Output Sink Current
00932666
00932667
Large-Signal Step Response
Output Voltage Swing vs. Temp. and Current
00932668
00932669
Output Source Current vs. Output Voltage and Temp.
Output Sink Current vs. Output Voltage and Temp.
00932671
00932670
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8
V+ = 5V, V− = GND = 0V, VCM = V+/2,
+
VOUT = V /2, TJ = 25˚C, unless otherwise noted (Continued)
Output Swing, Large Signal
Output Impedance vs. Frequency and Gain
00932672
00932673
Small-Signal Pulse Response vs. Temp.
Small-Signal Pulse Response vs. Load
00932674
00932675
Op Amp Voltage Noise vs. Frequency
Op Amp Current Noise vs. Frequency
00932676
00932677
9
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LM614
Typical Performance Characteristics (Op Amps)
LM614
Typical Performance Characteristics (Op Amps)
V+ = 5V, V− = GND = 0V, VCM = V+/2,
+
VOUT = V /2, TJ = 25˚C, unless otherwise noted (Continued)
Small-Signal Voltage Gain vs. Frequency and
Temperature
Small-Signal Voltage Gain vs. Frequency and Load
00932678
00932679
Follower Small-Signal Frequency Response
Common-Mode Input Voltage Rejection Ratio
00932681
00932680
Power Supply Current vs. Power Supply Voltage
Positive Power Supply Voltage Rejection Ratio
00932607
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00932621
10
V+ = 5V, V− = GND = 0V, VCM = V+/2,
+
VOUT = V /2, TJ = 25˚C, unless otherwise noted (Continued)
Negative Power Supply Voltage Rejection Ratio
Input Offset Current vs. Junction Temperature
00932622
00932624
Input Bias Current vs. Junction Temperature
00932638
Typical Performance Distributions
Average VOS Drift Industrial Temperature Range
Average VOS Drift Commercial Temperature Range
00932630
00932631
11
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LM614
Typical Performance Characteristics (Op Amps)
LM614
Typical Performance Distributions
(Continued)
Average IOS Drift Industrial Temperature Range
Average IOS Drift Commercial Temperature Range
00932633
00932634
Voltage Reference Broad-BandNoise Distribution
Op Amp Voltage Noise Distribution
00932635
00932636
Op Amp Current Noise Distribution
00932637
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12
LM614
Application Information
VOLTAGE REFERENCE
Reference Biasing
The voltage reference is of a shunt regulator topology that
models as a simple zener diode. With current Ir flowing in the
“forward” direction there is the familiar diode transfer function. Ir flowing in the reverse direction forces the reference
voltage to be developed from cathode to anode. The cathode may swing from a diode drop below V− to the reference
voltage or to the avalanche voltage of the parallel protection
diode, nominally 7V. A 5.0V reference with V+ = 3V is allowed.
Capacitors in parallel with the reference are allowed. See the
Reference AC Stability Range typical curve for capacitance
values — from 20 µA to 3 mA any capacitor value is stable.
With the reference’s wide stability range with resistive and
capacitive loads, a wide range of RC filter values will perform
noise filtering.
00932610
00932609
FIGURE 2. Reference Equivalent Circuit
FIGURE 1. Voltages Associated with Reference
(Current Source Ir is External)
The reference equivalent circuit reveals how Vris held at the
constant 1.2V by feedback, and how the FEEDBACK pin
passes little current.
To generate the required reverse current, typically a resistor
is connected from a supply voltage higher than the reference
voltage. Varying that voltage, and so varying Ir, has small
effect with the equivalent series resistance of less than an
ohm at the higher currents. Alternatively, an active current
source, such as the LM134 series, may generate Ir.
00932611
FIGURE 3. 1.2V Reference
Adjustable Reference
The FEEDBACK pin allows the reference output voltage,
Vro, to vary from 1.24V to 5.0V. The reference attempts to
hold Vr at 1.24V. If Vr is above 1.24V, the reference will
conduct current from Cathode to Anode; FEEDBACK current
always remains low. If FEEDBACK is connected to Anode,
then Vro = Vr = 1.24V. For higher voltages FEEDBACK is
held at a constant voltage above Anode — say 3.76V for Vro
= 5V. Connecting a resistor across the constant Vr generates
a current I=Vr/R1 flowing from Cathode into FEEDBACK
node. A Thevenin equivalent 3.76V is generated from FEEDBACK to Anode with R2=3.76/I. For a 1% error, use R1 such
that I is greater than one hundred times the FEEDBACK bias
current. For example, keep I ≥ 5.5µA.
00932612
FIGURE 4. Thevenin Equivalent
of Reference with 5V Output
13
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LM614
Application Information
(Continued)
00932613
00932616
R1 = Vr/I = 1.24/32µ = 39k
R2 = R1 {(Vro/Vr) − 1} = 39k {(5/1.24) − 1)} = 118k
FIGURE 8. Diode in Series with R1 Causes Voltage
across R1 and R2 to be Proportional to Absolute
Temperature (PTAT)
FIGURE 5. Resistors R1 and R2 Program
Reference Output Voltage to be 5V
Connecting a resistor across Cathode-to-FEEDBACK creates a 0 TC current source, but a range of TCs may be
synthesized.
Understanding that Vr is fixed and that voltage sources,
resistors, and capacitors may be tied to the FEEDBACK pin,
a range of Vr temperature coefficients may be synthesized.
00932617
I = Vr/R1 = 1.24/R1
00932614
FIGURE 6. Output Voltage has Negative Temperature
Coefficient (TC) if R2 has Negative TC
FIGURE 9. Current Source is Programmed by R1
00932615
00932618
FIGURE 7. Output Voltage has Positive TC
if R1 has Negative TC
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FIGURE 10. Proportional-to-Absolute-Temperature
Current Source
14
non-inverting input to V− on unused amps is preferred).
Choosing operating points that cause oscillation, such as
driving too large a capacitive load, is best avoided.
(Continued)
Op Amp Output Stage
These op amps, like their LM124 series, have flexible and
relatively wide-swing output stages. There are simple rules
to optimize output swing, reduce cross-over distortion, and
optimize capacitive drive capability:
1. Output Swing: Unloaded, the 42µA pull-down will bring
the output within 300 mV of V− over the military temperature range. If more than 42µA is required, a resistor from
output to V− will help. Swing across any load may be
improved slightly if the load can be tied to V+, at the cost
of poorer sinking open-loop voltage gain
2. Cross-over Distortion: The LM614 has lower cross-over
distortion (a 1 VBE deadband versus 3 VBE for the
LM124), and increased slew rate as shown in the characteristic curves. A resistor pull-up or pull-down will force
class-A operation with only the PNP or NPN output
transistor conducting, eliminating cross-over distortion
3. Capacitive Drive: Limited by the output pole caused by
the output resistance driving capacitive loads, a
pull-down resistor conducting 1 mA or more reduces the
output stage NPN re until the output resistance is that of
the current limit 25Ω. 200pF may then be driven without
oscillation.
00932619
FIGURE 11. Negative-TC Current Source
Hysteresis
The reference voltage depends, slightly, on the thermal history of the die. Competitive micro-power products
vary — always check the data sheet for any given device. Do
not assume that no specification means no hysteresis.
OPERATIONAL AMPLIFIERS
Any amp or the reference may be biased in any way with no
effect on the other amps or reference, except when a substrate diode conducts (see Guaranteed Electrical Characteristics (Note 1)). One amp input may be outside the
common-mode range, another amp may be operated as a
comparator, another with all terminals floating with no effect
on the others (tying inverting input to output and
Op Amp Input Stage
The lateral PNP input transistors, unlike most op amps, have
BVEBO equal to the absolute maximum supply voltage. Also,
they have no diode clamps to the positive supply nor across
the inputs. These features make the inputs look like high
impedances to input sources producing large differential and
common-mode voltages.
15
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LM614
Application Information
LM614
Typical Applications
00932642
FIGURE 12. Simple Low Quiescent Drain Voltage Regulator. Total supply current approximately 320µA, when VIN =
+5V.
00932643
*10k must be low
t.c. trimpot.
FIGURE 13. Ultra Low Noise 10.00V Reference. Total output noise is typically 14µVRMS.
00932644
VOUT = (R1 /Pe + 1) V REF
R1, R2 should be 1% metal film
Pβ should be low T.C. trim pot
FIGURE 14. Slow Rise Time Upon Power-Up, Adjustable Transducer Bridge Driver. Rise time is approximately 1ms.
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16
LM614
Typical Applications
(Continued)
00932645
FIGURE 15. Transducer Data Acquisition System. Set zero code voltage, then adjust 10Ω gain adjust pot for full
scale.
17
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LM614
Simplified Schematic Diagrams
Op Amp
00932602
Reference / Bias
00932603
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18
LM614 Quad Operational Amplifier and Adjustable Reference
Physical Dimensions
inches (millimeters)
unless otherwise noted
16-Lead Molded Small Outline Package (WM)
NS Package Number M16B
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