Datasheet LF147, LF347 Datasheet (National Semiconductor)

August 2000

LF147/LF347
Wide Bandwidth Quad JFET Input Operational Amplifiers

LF147/LF347 Wide Bandwidth Quad JFET Input Operational Amplifiers

General Description

The LF147 is a low cost, high speed quad JFET input
operational amplifier with an internally trimmed input offset
voltage (BI-FET II
supply current and yet maintains a large gain bandwidth
product and a fast slew rate. In addition, well matched high
voltage JFET input devices provide very low input bias and
offset currents. The LF147 is pin compatible with the stan­dard LM148. This feature allows designers to immediately
upgrade the overall performance of existing LF148 and
LM124 designs.

The LF147 may be used in applications such as high speed
integrators, fast D/A converters, sample-and-hold circuits
and many other circuits requiring low input offset voltage,
low input bias current, high input impedance, high slew rate
and wide bandwidth. The device has low noise and offset
voltage drift.

™

technology). The device requires a low

Simplified Schematic

1

⁄4Quad

Features

n Internally trimmed offset voltage: 5 mV max
n Low input bias current: 50 pA
n Low input noise current: 0.01 pA/
n Wide gain bandwidth: 4 MHz
n High slew rate: 13 V/µs
n Low supply current: 7.2 mA
n High input impedance: 10
n Low total harmonic distortion: ≤0.02%
n Low 1/f noise corner: 50 Hz
n Fast settling time to 0.01%: 2 µs

√

Hz

12

Connection Diagram

Dual-In-Line Package

Ω

00564713

BI-FET II™is a trademark of National Semiconductor Corporation.

© 2004 National Semiconductor Corporation DS005647 www.national.com

Note 1: LF147 available as per JM38510/11906.

Top View

Order Number LF147J, LF147J-SMD, LF347M,

LF347BN, LF347N, LF147J/883,

or JL147 BCA (Note 1)

See NS Package Number J14A, M14A or N14A

00564701

Absolute Maximum Ratings (Note 2)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

LF147/LF347

Supply Voltage

Differential Input Voltage

Input Voltage Range

(Note 3)

Output Short Circuit Continuous Continuous

Duration (Note 4)

Power Dissipation 900 mW 1000 mW

(Notes 5, 11)

T

max 150˚C 150˚C

j

θ

jA

Ceramic DIP (J) Package 70˚C/W

Plastic DIP (N) Package 75˚C/W

LF147 LF347B/LF347

±

22V

±

38V

±

19V

±
±
±

18V

30V

15V

Operating Temperature (Note 6) (Note 6)

Range

Storage Temperature

Range −65˚C≤T

Lead Temperature

(Soldering, 10 sec.) 260˚C 260˚C

Soldering Information

Dual-In-Line Package

Soldering (10 seconds) 260˚C

Small Outline Package

Vapor Phase (60 seconds) 215˚C

Infrared (15 seconds) 220˚C

See AN-450 “Surface Mounting Methods and Their Effect
on Product Reliability” for other methods of soldering
surface mount devices.

ESD Tolerance (Note 12) 900V

LF147 LF347B/LF347

≤150˚C

A

Surface Mount Narrow (M) 100˚C/W

Surface Mount Wide (WM) 85˚C/W

DC Electrical Characteristics (Note 7)

Symbol Parameter Conditions LF147 LF347B LF347 Units

Min Typ Max Min Typ Max Min Typ Max

V

OS

∆V

I

OS

I

B

R

IN

A

VOL

V

O

V

CM

CMRR Common-Mode Rejection Ratio R

PSRR Supply Voltage Rejection Ratio (Note 9) 80 100 80 100 70 100 dB

I

S

Input Offset Voltage RS=10 kΩ,TA=25˚C 1 5 3 5 5 10 mV

Over Temperature 8 7 13 mV

/∆T Average TC of Input Offset RS=10 kΩ 10 10 10 µV/˚C

OS

Voltage

Input Offset Current Tj=25˚C, (Notes 7, 8) 25 100 25 100 25 100 pA

Over Temperature 25 4 4 nA

Input Bias Current Tj=25˚C, (Notes 7, 8) 50 200 50 200 50 200 pA

Over Temperature 50 8 8 nA

Input Resistance Tj=25˚C 10

12

10

12

10

12

Large Signal Voltage Gain VS=±15V, TA=25˚C 50 100 50 100 25 100 V/mV

V

=±10V, RL=2 kΩ

O

Over Temperature 25 25 15 V/mV

Output Voltage Swing VS=±15V, RL=10 kΩ

Input Common-Mode Voltage VS=±15V

±12±
±

11 +15

13.5

±12±
±

11 +15

13.5

±12±

13.5 V

±

11 +15 V

Range −12 −12 −12 V

≤10 kΩ 80 100 80 100 70 100 dB

S

Supply Current 7.2 11 7.2 11 7.2 11 mA

Ω

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AC Electrical Characteristics (Note 7)

Symbol Parameter Conditions LF147 LF347B LF347 Units

Min Typ Max Min Typ Max Min Typ Max

Amplifier to Amplifier Coupling T

SR Slew Rate V

GBW Gain-Bandwidth Product V

e

n

i

n

Equivalent Input Noise Voltage TA=25˚C, RS=100Ω,202020

Equivalent Input Noise Current Tj=25˚C, f=1000 Hz 0.01 0.01 0.01

=25˚C, −120 −120 −120 dB

A

f=1 Hz−20 kHz

(Input Referred)

=±15V, TA=25˚C 8 13 8 13 8 13 V/µs

S

=±15V, TA=25˚C 2.2 4 2.2 4 2.2 4 MHz

S

f=1000 Hz

LF147/LF347

THD Total Harmonic Distortion AV=+10, RL=10k,

=20 Vp-p,

V

O

<

0.02

<

0.02

<

0.02 %

BW=20 Hz−20 kHz

Note 2: 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.

Note 3: Unless otherwise specified the absolute maximum negative input voltage is equal to the negative power supply voltage.

Note 4: 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 5: For operating at elevated temperature, these devices must be derated based on a thermal resistance of θ
Note 6: The LF147 is available in the military temperature range −55˚C≤T

range 0˚C≤T

Note 7: Unless otherwise specified the specifications apply over the full temperature range and for V
V

OS,IB

Note 8: The input bias currents are junction leakage currents which approximately double for every 10˚C increase in the junction temperature, T
production test time, the input bias currents measured are correlated to junction temperature. In normal operation the junction temperature rises above the ambient
temperature as a result of internal power dissipation, P
recommended if input bias current is to be kept to a minimum.

Note 9: Supply voltage rejection ratio is measured for both supply magnitudes increasing or decreasing simultaneously in accordance with common practice from
V

=±5V to±15V for the LF347 and LF347B and from VS=±20V to±5V for the LF147.

S

Note 10: Refer to RETS147X for LF147D and LF147J military specifications.

Note 11: 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 12: Human body model, 1.5 kΩ in series with 100 pF.

≤70˚C. Junction temperature can rise to Tjmax = 150˚C.

A

, and IOSare measured at VCM=0.

D.Tj=TA+θjAPD

≤125˚C, while the LF347B and the LF347 are available in the commercial temperature

A

=±20V for the LF147 and for VS=±15V for the LF347B/LF347.

S

where θjAis the thermal resistance from junction to ambient. Use of a heat sink is

.

jA

. Due to limited

j

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Typical Performance Characteristics

Input Bias Current Input Bias Current

LF147/LF347

00564714

Positive Common-Mode

Supply Current

00564716

Input Voltage Limit

Negative Common-Mode

Input Voltage Limit Positive Current Limit

00564715

00564717

00564718

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00564719

Typical Performance Characteristics (Continued)

Negative Current Limit Output Voltage Swing

LF147/LF347

00564720

Output Voltage Swing Gain Bandwidth

00564722

Bode Plot Slew Rate

00564721

00564723

00564724

00564725

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Typical Performance Characteristics (Continued)

Distortion vs Frequency

LF147/LF347

Undistorted Output Voltage

Swing

Open Loop Frequency

Response

Power Supply Rejection

Ratio

00564726

00564728

00564727

Common-Mode Rejection

Ratio

00564729

Equivalent Input Noise

Voltage

00564730 00564731

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Typical Performance Characteristics (Continued)

Open Loop Voltage Gain Output Impedance

LF147/LF347

Inverter Settling Time

00564732

00564734

00564733

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Pulse Response R

LF147/LF347

=2 kΩ,CL=10 pF

L

Small Signal Inverting

Large Signal Inverting

00564706

Small Signal Non-Inverting

00564704

00564705

Current Limit (RL=100Ω)

Large Signal Non-Inverting

00564707

Application Hints

The LF147 is an op amp with an internally trimmed input
offset voltage and JFET input devices (BI-FET II). 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

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00564708

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.

Application Hints (Continued)

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 by a zener reference
which allows normal circuit operation on
plies. Supply voltages less than these may result in lower
gain bandwidth and slew rate.

The LF147 will drivea2kΩ load resistance to
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

±

4.5V power sup-

±

10V over the

LF147/LF347

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.

Detailed Schematic

00564709

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Typical Applications

LF147/LF347

Digitally Selectable Precision Attenuator

All resistors 1% tolerance

Accuracy of better than 0.4% with standard 1% value resistors

•

No offset adjustment necessary
Expandable to any number of stages

•

Very high input impedance

•

A1 A2 A3 V

000 0

001 −1dB

010 −2dB

011 −3dB

100 −4dB

101 −5dB

110 −6dB

111 −7dB

00564710

O

Attenuation

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Typical Applications (Continued)

Long Time Integrator with Reset, Hold and Starting Threshold Adjustment

LF147/LF347

V

•

•

•

•

starts from zero and is equal to the integral of the input voltage with respect to the threshold voltage:

OUT

Output starts when VIN≥V

TH

Switch S1 permits stopping and holding any output value
Switch S2 resets system to zero

00564711

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Typical Applications (Continued)

LF147/LF347

Universal State Variable Filter

For circuit shown:

=3 kHz, f

f

o

Q=3.4

Passband gain:

Highpass —0.1

Bandpass —1

Lowpass —1

Notch —10

foxQ≤200 kHz

•

10V peak sinusoidal output swing without slew limiting to 200 kHz

•

See LM148 data sheet for design equations

•

NOTCH

=9.5 kHz

00564712

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Physical Dimensions inches (millimeters) unless otherwise noted

Ceramic Dual-In-Line Package (J)

Order Number LF147J, LM147J-SMD or LF147J/883

NS Package Number J14A

LF147/LF347

S.O. Package (M)

Order Number LF347M or LF347MX

NS Package Number M14A

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

Molded Dual-In-Line Package (N)

Order Number LF347BN or LF347N

NS Package Number N14A

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DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

LF147/LF347 Wide Bandwidth Quad JFET Input Operational Amplifiers

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systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
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.

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