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
™
technology). The device requires a low 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.
Features
n Internally trimmed offset voltage: 5 mV max
n Low input bias current: 50 pA
n Low input noise current:
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
12
Ω
n Low total harmonic distortion A
V
=
10,:
<
0.02
%
R
L
=
10k, V
O
=
20 Vp-p, BW=20 Hz−20 kHz
n Low 1/f noise corner: 50 Hz
n Fast settling time to 0.01%:2µs
Simplified Schematic Connection Diagram
BI-FET II™is a trademarkof National Semiconductor Corporation.
1
⁄4Quad
DS005647-13
Dual-In-Line Package
DS005647-1
Note 1: Available per SMD#8102306, JM38510/11906.
Top View
Order Number LF147J, LF347M, LF347BN,
LF347N or LF147J/883 (Note 1)
See NS Package Number J14A, M14A or N14A
May 1999
LF147/LF347 Wide Bandwidth Quad JFET Input Operational Amplifiers
© 1999 National Semiconductor Corporation DS005647 www.national.com
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 LF347B/LF347
Supply Voltage
±
22V
±
18V
Differential Input Voltage
±
38V
±
30V
Input Voltage Range
±
19V
±
15V
(Note 3)
Output Short Circuit Continuous Continuous
Duration (Note 4)
Power Dissipation 900 mW 1000 mW
(Notes 5, 11)
T
j
max 150˚C 150˚C
θ
jA
Ceramic DIP (J) Package 70˚C/W
Plastic DIP (N) Package 75˚C/W
Surface Mount Narrow (M) 100˚C/W
LF147 LF347B/LF347
Surface Mount Wide (WM) 85˚C/W
Operating Temperature (Note 6) (Note 6)
Range
Storage Temperature
Range −65˚C≤T
A
≤150˚C
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
DC Electrical Characteristics (Note 7)
Symbol Parameter Conditions LF147 LF347B LF347 Units
Min Typ Max Min Typ Max Min Typ Max
V
OS
Input Offset Voltage R
S
=
10 kΩ,T
A
=
25˚C 1 5 3 5 5 10 mV
Over Temperature 8 7 13 mV
∆V
OS
/∆T Average TC of Input Offset R
S
=
10 kΩ 10 10 10 µV/˚C
Voltage
I
OS
Input Offset Current T
j
=
25˚C, (Notes 7, 8) 25 100 25 100 25 100 pA
Over Temperature 25 4 4 nA
I
B
Input Bias Current T
j
=
25˚C, (Notes 7, 8) 50 200 50 200 50 200 pA
Over Temperature 50 8 8 nA
R
IN
Input Resistance T
j
=
25˚C 10
12
10
12
10
12
Ω
A
VOL
Large Signal Voltage Gain V
S
=
±
15V, T
A
=
25˚C 50 100 50 100 25 100 V/mV
V
O
=
±
10V, R
L
=
2kΩ
Over Temperature 25 25 15 V/mV
V
O
Output Voltage Swing V
S
=
±
15V, R
L
=
10 kΩ
±12±
13.5
±12±
13.5
±12±
13.5 V
V
CM
Input Common-Mode Voltage V
S
=
±
15V
±
11 +15
±
11 +15
±
11 +15 V
Range −12 −12 −12 V
CMRR Common-Mode Rejection Ratio R
S
≤10 kΩ 80 100 80 100 70 100 dB
PSRR Supply Voltage Rejection Ratio (Note 9) 80 100 80 100 70 100 dB
I
S
Supply Current 7.2 11 7.2 11 7.2 11 mA
www.national.com 2
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
A
=
25˚C, −120 −120 −120 dB
f=1 Hz−20 kHz
(Input Referred)
SR Slew Rate V
S
=
±
15V, T
A
=
25˚C 8 13 8 13 8 13 V/µs
GBW Gain-Bandwidth Product V
S
=
±
15V, T
A
=
25˚C 2.2 4 2.2 4 2.2 4 MHz
e
n
Equivalent Input Noise Voltage T
A
=
25˚C, R
S
=
100Ω,202020
f
=
1000 Hz
i
n
Equivalent Input Noise Current T
j
=
25˚C, f=1000 Hz 0.01 0.01 0.01
Note 2: Absolute MaximumRatings indicate limits beyond which damage to the device may occur.Operating Ratingsindicate conditionsfor whichthe deviceis 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
jA
.
Note 6: The LF147 is available in the military temperature range −55˚C≤T
A
≤125˚C, while the LF347B and the LF347 are available in the commercial temperature
range 0˚C≤T
A
≤70˚C. Junction temperature can rise to Tjmax=150˚C.
Note 7: Unless otherwisespecified the specifications apply over the full temperature range and forV
S
=
±
20V for the LF147 and forV
S
=
±
15V for the LF347B/LF347.
V
OS,IB
, and IOSare measured at V
CM
=
0.
Note 8: The input bias currents are junction leakage currents which approximately double for every 10˚C increase in the junction temperature, T
j
. Due to limited 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
D.Tj
=
T
A+θjAPD
where θjAis the thermal resistance from junction to ambient. Use of a heat sink is 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
S
=
±
5V to±15V for the LF347 and LF347B and from V
S
=
±
20V to±5V for the LF147.
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 out-
side guaranteed limits.
Note 12: Human body model, 1.5 kΩ in series with 100 pF.
www.national.com3
Typical Performance Characteristics
Input Bias Current
DS005647-14
Input Bias Current
DS005647-15
Supply Current
DS005647-16
Positive Common-Mode
Input Voltage Limit
DS005647-17
Negative Common-Mode
Input Voltage Limit
DS005647-18
Positive Current Limit
DS005647-19
Negative Current Limit
DS005647-20
Output Voltage Swing
DS005647-21
Output Voltage Swing
DS005647-22
www.national.com 4
Typical Performance Characteristics (Continued)
Gain Bandwidth
DS005647-23
Bode Plot
DS005647-24
Slew Rate
DS005647-25
Distortion vs Frequency
DS005647-26
Undistorted Output Voltage
Swing
DS005647-27
Open Loop Frequency
Response
DS005647-28
Common-Mode Rejection
Ratio
DS005647-29
Power Supply Rejection
Ratio
DS005647-30
Equivalent Input Noise
Voltage
DS005647-31
www.national.com5
Typical Performance Characteristics (Continued)
Open Loop Voltage Gain
DS005647-32
Output Impedance
DS005647-33
Inverter Settling Time
DS005647-34
www.national.com 6
Pulse Response R
L
=
2kΩ,C
L
=
10 pF
Application Hints
The LF147 is an op amp with an internally trimmed input offset voltage and JFETinput 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 differentialinput voltage is independent ofthe 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.
Small Signal Inverting
DS005647-4
Small Signal Non-Inverting
DS005647-5
Large Signal Inverting
DS005647-6
Large Signal Non-Inverting
DS005647-7
Current Limit (R
L
=
100Ω)
DS005647-8
www.national.com7
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 exceedthe 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
±
4.5V power supplies. Supply voltages less than these may result in lower
gain bandwidth and slew rate.
The LF147 will drivea2kΩload 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 isresistive. The parallel resistance andcapacitance
from the input of the device (usually the invertinginput) 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 frequencya lead capacitor should be placedfrom 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
DS005647-9
www.national.com 8
Typical Applications
Digitally Selectable Precision Attenuator
DS005647-10
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
O
Attenuation
000 0
0 0 1 −1 dB
0 1 0 −2 dB
0 1 1 −3 dB
1 0 0 −4 dB
1 0 1 −5 dB
1 1 0 −6 dB
1 1 1 −7 dB
www.national.com9
Typical Applications (Continued)
Long Time Integrator with Reset, Hold and Starting Threshold Adjustment
DS005647-11
•
V
OUT
starts from zero and is equal to the integral of the input voltage with respect to the threshold voltage:
•
Output starts when VIN≥V
TH
•
Switch S1 permits stopping and holding any output value
•
Switch S2 resets system to zero
www.national.com 10
Typical Applications (Continued)
Universal State Variable Filter
DS005647-12
For circuit shown:
f
o
=
3 kHz, f
NOTCH
=
9.5 kHz
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
www.national.com11
Physical Dimensions inches (millimeters) unless otherwise noted
Ceramic Dual-In-Line Package (J)
Order Number LF147J or LF147J/883
NS Package Number J14A
S.O. Package (M)
Order Number LF347M
NS Package Number M14A
www.national.com 12
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
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
labeling, can be reasonably expected to result in a
significant injury to the user.
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 system, or to affect its
safety or effectiveness.
National Semiconductor
Corporation
Americas
Tel: 1-800-272-9959
Fax: 1-800-737-7018
Email: support@nsc.com
National Semiconductor
Europe
Fax: +49 (0) 1 80-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 1 80-530 85 85
English Tel: +49 (0) 1 80-532 78 32
Français Tel: +49 (0) 1 80-532 93 58
Italiano Tel: +49 (0) 1 80-534 16 80
National Semiconductor
Asia Pacific Customer
Response Group
Tel: 65-2544466
Fax: 65-2504466
Email: sea.support@nsc.com
National Semiconductor
Japan Ltd.
Tel: 81-3-5639-7560
Fax: 81-3-5639-7507
www.national.com
Molded Dual-In-Line Package (N)
Order Number LF347BN or LF347N
NS Package Number N14A
LF147/LF347 Wide Bandwidth Quad JFET Input Operational Amplifiers
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.
Loading...