TI LF444QML

LF444QML
LF444QML Quad Low Power JFET Input Operational Amplifier
Literature Number: SNOSAO9
LF444QML
Quad Low Power JFET Input Operational Amplifier
General Description
Features
The LF444 quad low power operational amplifier provides
many of the same AC characteristics as the industry standard
LM148 while greatly improving the DC characteristics of the
LM148. The amplifier has the same bandwidth, slew rate, and
gain (10 kΩ load) as the LM148 and only draws one fourth the
supply current of the LM148. In addition the well matched high
voltage JFET input devices of the LF444 reduce the input bias
and offset currents by a factor of 10,000 over the LM148. The
LF444 also has a very low equivalent input noise voltage for
a low power amplifier.
The LF444 is pin compatible with the LM148 allowing an immediate 4 times reduction in power drain in many applications. The LF444 should be used wherever low power
dissipation and good electrical characteristics are the major
considerations.
■
■
■
■
■
■
■
■
¼ supply current of a LM148: 250 μA/Amplifier (max)
Low input bias current: 100 pA (max)
High gain bandwidth: 1 MHz
High slew rate: 1 V/μs
Low noise voltage for low power
Low input noise current
High input impedance: 1012Ω
High gain, VO = ±10V, RL = 10KΩ: 25K (min)
Ordering Information
NS Part Number
SMD Part Number
LF444MD/883
NS Package Number
Package Description
D14D
14LD Sidebraze Ceramic Dip
Connection Diagram
Dual-In-Line Package
20149502
Top View
See NS Package Number D14D
BI-FET® is a registered trademark of National Semiconductor Corporation.
© 2010 National Semiconductor Corporation
201495
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LF444QML Quad Low Power JFET Input Operational Amplifier
October 16, 2010
LF444QML
Simplified Schematic
1/4 Quad
20149501
Detailed Schematic
1/4 Quad
20149511
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2
LF444QML
Absolute Maximum Ratings (Note 1)
Supply Voltage
Differential Input Voltage
Input Voltage Range (Note 4)
Output Short Circuit Duration (Note 5)
Power Dissipation (Note 2), (Note 3)
TJmax
±18V
±30V
±15V
Continuous
900 mW
150°C
100°C/W
θJA (Typical)
Operating Temperature Range
−55°C ≤ TA ≤ 125°C
−65°C ≤ TA ≤ 150°C
Rating to be determined
Storage Temperature Range
ESD Tolerance (Note 6)
Quality Conformance Inspection
Mil-Std-883, Method 5005 - Group A
Subgroup
Description
Temp (°C)
1
Static tests at
+25
2
Static tests at
+125
3
Static tests at
-55
4
Dynamic tests at
+25
5
Dynamic tests at
+125
6
Dynamic tests at
-55
7
Functional tests at
+25
8A
Functional tests at
+125
8B
Functional tests at
-55
9
Switching tests at
+25
10
Switching tests at
+125
11
Switching tests at
-55
12
Settling time at
+25
13
Settling time at
+125
14
Settling time at
-55
3
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LF444QML
LF444 Electrical Characteristics
DC Parameters
The following conditions apply, unless otherwise specified.
Symbol
VIO
IIO
+IIB
Parameter
Input Offset Voltage
Input Offset Current
Input Bias Current
VS = ±15V, VCM = 0V, RS = 0Ω, RL = 0Ω
Conditions
Notes
RS = 10KΩ
RL = 10KΩ
RL = 10KΩ
-IIB
Input Bias Current
+AVS
Large Signal Voltage Gain
-AVS
Large Signal Voltage Gain
+VO
Output Voltage Swing
RL = 10KΩ, VI = +1V
-VO
Output Voltage Swing
RL = 10KΩ, VI = -1V
VCM
Input Common Mode Voltage
Range
CMRR
Common Mode Rejection Ratio
RS = 10KΩ, VCM = ±9V
PSRR+
Power Supply Rejection Ratio
PSRR-
Power Supply Rejection Ratio
IS
Supply Current
RL = 10KΩ
VO = 0 to +10V,
Min
Max
Unit
Subgroups
-10
10
mV
1
-14
14
mV
2, 3
-0.05
0.05
nA
1
-10
10
nA
2
-0.10
0.10
nA
1
-20
20
nA
2
-0.10
0.10
nA
1
-20
20
nA
2
25
V/mV
1
15
V/mV
2, 3
25
V/mV
1
15
V/mV
2, 3
12
V
1, 2, 3
-12
V
1, 2, 3
-9
V
1, 2, 3
70
dB
1, 2, 3
VS = ±15V to VS = ±6V
70
dB
1, 2, 3
VS = ±15V to VS = ±6V
70
dB
1, 2, 3
1, 2, 3
RL = 10KΩ, RS = 10KΩ
VO = 0 to -10V,
RL = 10KΩ, RS = 10KΩ
(Note 8)
(Note 8)
(Note 7)
+IOS
Output Short Circuit Current
VI = 1V
-IOS
Output Short Circuit Current
VI = -1V
9
1.0
mA
-3.0
-20
mA
1
-3.0
-40
mA
2, 3
3.0
20
mA
1
3.0
40
mA
2, 3
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed
specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
Note 2: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJmax (maximum junction temperature), θJA (package
junction to ambient thermal resistance), and TA (ambient temperature). The maximum allowable power dissipation at any temperature is PDmax = (TJmax - TA)/
θJA or the number given in the Absolute Maximum Ratings, whichever is lower.
Note 3: Max. Power Dissipation is defined by the package characteristics. Operating the part near the Max. Power Dissipation may cause the part to operate
outside guaranteed limits.
Note 4: Unless otherwise specified the absolute maximum negative input voltage is equal to the negative power supply voltage.
Note 5: Any of the amplifier outputs can be shorted to ground indefinitely, however, more than one should not be simultaneously shorted as the maximum junction
temperature will be exceeded.
Note 6: Human body model, 1.5 kΩ in series with 100 pF.
Note 7: Parameter tested go-no-go only. Guaranteed by the CMRR test.
Note 8: Datalog in K = V/mV.
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LF444QML
Typical Performance Characteristics
Input Bias Current
Input Bias Current
20149512
20149513
Supply Current
Positive Common-Mode
Input Voltage Limit
20149514
20149515
Negative Common-Mode
Input Voltage Limit
Positive Current Limit
20149517
20149516
5
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LF444QML
Negative Current Limit
Output Voltage Swing
20149519
20149518
Output Voltage Swing
Gain Bandwidth
20149521
20149520
Bode Plot
Slew Rate
20149523
20149522
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6
LF444QML
Distortion vs Frequency
Undistorted Output
Voltage Swing
20149524
20149525
Open Loop
Frequency Response
Common-Mode
Rejection Ratio
20149526
20149527
Power Supply
Rejection Ratio
Equivalent Input
Noise Voltage
20149528
20149529
7
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LF444QML
Open Loop Voltage Gain
Output Impedance
20149530
20149531
Inverter Settling Time
20149532
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8
LF444QML
Pulse Response
RL = 10 kΩ, CL = 10 pF
Small Signal Inverting
Small Signal Non-Inverting
20149506
20149507
Large Signal Inverting
Large Signal Non-Inverting
20149508
20149509
9
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LF444QML
The amplifiers will drive a 10 kΩ load resistance to ±10V over
the full temperature range. If the amplifier is forced to drive
heavier load currents, however, an increase in input offset
voltage may occur on the negative voltage swing and finally
reach an active current limit on both positive and negative
swings.
Precautions should be taken to ensure that the power supply
for the integrated circuit never becomes reversed in polarity
or that the unit is not inadvertently installed backwards in a
socket as an unlimited current surge through the resulting
forward diode within the IC could cause fusing of the internal
conductors and result in a destroyed unit.
As with most amplifiers, care should be taken with lead dress,
component placement and supply decoupling in order to ensure stability. For example, resistors from the output to an
input should be placed with the body close to the input to
minimize “pick-up” and maximize the frequency of the feedback pole by minimizing the capacitance from the input to
ground.
A feedback pole is created when the feedback around any
amplifier is resistive. The parallel resistance and capacitance
from the input of the device (usually the inverting input) to AC
ground set the frequency of the pole. In many instances the
frequency of this pole is much greater than the expected 3 dB
frequency of the closed loop gain and consequently there is
negligible effect on stability margin. However, if the feedback
pole is less than approximately 6 times the expected 3 dB
frequency a lead capacitor should be placed from the output
to the input of the op amp. The value of the added capacitor
should be such that the RC time constant of this capacitor and
the resistance it parallels is greater than or equal to the original feedback pole time constant.
Application Hints
This device is a quad low power op amp with JFET input devices ( BI-FET®). These JFETs have large reverse breakdown
voltages from gate to source and drain eliminating the need
for clamps across the inputs. Therefore, large differential input voltages can easily be accommodated without a large
increase in input current. The maximum differential input voltage is independent of the supply voltages. However, neither
of the input voltages should be allowed to exceed the negative
supply as this will cause large currents to flow which can result
in a destroyed unit.
Exceeding the negative common-mode limit on either input
will force the output to a high state, potentially causing a reversal of phase to the output. Exceeding the negative common-mode limit on both inputs will force the amplifier output
to a high state. In neither case does a latch occur since raising
the input back within the common-mode range again puts the
input stage and thus the amplifier in a normal operating mode.
Exceeding the positive common-mode limit on a single input
will not change the phase of the output; however, if both inputs
exceed the limit, the output of the amplifier will be forced to a
high state.
The amplifiers will operate with a common-mode input voltage
equal to the positive supply; however, the gain bandwidth and
slew rate may be decreased in this condition. When the negative common-mode voltage swings to within 3V of the negative supply, an increase in input offset voltage may occur.
Each amplifier is individually biased to allow normal circuit
operation with power supplies of ±3.0V. Supply voltages less
than these may degrade the common-mode rejection and restrict the output voltage swing.
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10
LF444QML
Typical Application
pH Probe Amplifier/Temperature Compensator
20149510
***For R2 = 50kΩ, R4 = 330k ±1%
For R2 = 100k, R4 = 75k ±1%
For R2 = 200k, R4 = 56k ±1%
**Polystyrene
*Film resistor type RN60C
To calibrate, insert probe in pH =7 solution. Set the “TEMPERATURE ADJUST” pot, R2, to correspond to the solution temperature: full clockwise for 0°C, and
proportionately for intermediate temperatures, using a turns-counting dial. Then set “CALIBRATE” pot so output reads 7V.
Typical probe = Ingold Electrodes #465-35
11
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LF444QML
Revision History
Date Released
Revision
12/16/2010
A
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Section
Changes
New release to corporate format
12
1 MDS datasheet converted to standard corporate
format. MDS MNLF444M-X Rev 0AL will be
archived.
LF444QML
Physical Dimensions inches (millimeters) unless otherwise noted
See NS Package Number D14D
13
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LF444QML Quad Low Power JFET Input Operational Amplifier
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