lf412.pdf

April 1999

LF412

Low Offset, Low Drift Dual JFET Input Operational

Amplifier

General Description

These devices are low cost, high speed, JFET input opera-

tional amplifiers with very low input offset voltage and guar-

anteed input offset voltage drift. They require low supply cur-

rent yet maintain a large gain bandwidth product and fast

slew rate. In addition, well matched high voltage JFET input

devices provide very low input bias and offset currents.

LF412 dual is pin compatible with the LM1558, allowing de-

signers to immediately upgrade the overall performance of

existing designs.

These amplifiers may be used in applications such as high

speed integrators, fast D/A converters, sample and hold cir-

cuits and many other circuits requiring low input offset volt-

age and drift, low input bias current, high input impedance,

high slew rate and wide bandwidth.

Features

n Internally trimmed offset voltage: 1 mV (max)

n Input offset voltage drift: 10 µV/˚C (max)

n Low input bias current: 50 pA

n Low input noise current:

n Wide gain bandwidth: 3 MHz (min)

n High slew rate: 10V/µs (min)

n Low supply current: 1.8 mA/Amplifier

n High input impedance: 10 12

Typical Connection

Connection Diagrams

Metal Can Package

DS005656-41

DS005656-42

Order Number LF412AMH, LF412MH,

LF412CH or LF412MH/883 (Note 1)

See NS Package Number H08A

Ordering Information

LF412XYZ

X indicates electrical grade

Y indicates temperature range

“M” for military

“C” for commercial

Z indicates package type

“H” or “N”

Dual-In-Line Package

DS005656-44

Order Number LF412ACN, LF412CN

or LF412MJ/883 (Note 1)

See NS Package Number J08A or N08E

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

DS005656

www.national.com

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

1/2 Dual

DS005656-43

Note 1: Available per JM38510/11905

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.

(Note 11)

LF412A

LF412

H Package

N Package

Supply Voltage

± 22V

± 18V

T j max

150˚C

115˚C

Differential Input Voltage

± 38V

± 30V

q jA (Typical)

152˚C/W

115˚C/W

Input voltage Range

(Note 3)

Operating Temp. Range

(Note 6)

± 19V

± 15V

Storage Temp.

−65˚C

T A £

150˚C −65˚C

T A £

150˚C

Output Short Circuit

Duration (Note 4)

Continuous Continuous

H Package

Range

Lead Temp.

(Soldering, 10 sec.)

N Package

260˚C

ESD Tolerance

(Note 13)

Power Dissipation

(Note 12)

(Note 5)

670 mW

1700V

DC Electrical Characteristics

(Note 7)

Symbol

Parameter

Conditions

LF412A

LF412

Units

Min

Typ

Max Min

Typ

Max

V OS

Input Offset Voltage

R S = 10 k W ,T A = 25˚C

0.5

1.0

3.0

D V OS / D T Average TC of Input

R S = 10 k W (Note 8)

µV/˚C

Offset Voltage

I OS

Input Offset Current

V S = ± 15V

T j = 25˚C

100

(Notes 7, 9)

T j = 70˚C

T j = 125˚C

I B

Input Bias Current

V S = ± 15V

T j =25˚C

200

(Notes 7, 9)

T j =70˚C

T j =125˚C

R IN

Input Resistance

T j =25˚C

10 12

A VOL

Large Signal Voltage

V S = ± 15V, V O = ± 10V,

200

V/mV

Gain

R L =2k, T A =25˚C

Over Temperature

200

V/mV

V O

Output Voltage Swing

V S = ± 15V, R L =10k

± 12 ± 13.5

V CM

Input Common-Mode

± 16 +19.5

± 11 +14.5

Voltage Range

−16.5

−11.5

CMRR

Common-Mode

R S £

10k

100

Rejection Ratio

PSRR

Supply Voltage

(Note 10)

100

Rejection Ratio

I S

3.6 5.6 3.6 6.5 mA

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.

Supply Current

V O = 0V, R L =

AC Electrical Characteristics

(Note 7)

Symbol

Parameter

Conditions

LF412A

LF412

Units

Min

Typ

Max

Min

Typ

Max

Amplifier to Amplifier

T A = 25˚C, f = 1 Hz-20 kHz

−120

Coupling

(Input Referred)

Slew Rate

V S = ± 15V, T A = 25˚C

V/µs

GBW

Gain-Bandwidth Product

V S = ± 15V, T A = 25˚C

2.7

MHz

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AC Electrical Characteristics (Continued)

(Note 7)

Symbol

Parameter

Conditions

LF412A

LF412

Units

Min

Typ

Max

Min

Typ

Max

e n

Equivalent Input Noise

T A =25˚C, R S =100

Voltage

f=1 kHz

i n

Equivalent Input Noise

T A =25˚C, f=1 kHz

0.01

Current

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 indefintely, 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

q jA .

125˚C. The temperature

range is designated by the position just before the package type in the device number. A “C” indicates the commercial temperature range and an “M” indicates the

military temperature range. The military temperature range is available in “H” package only. In all cases the maximum operating temperature is limited by internal junc-

tion temperature T j max.

Note 7: Unless otherwise specified, the specifications apply over the full temperature range and for V S = ± 20V for the LF412A and for V S = ± 15V for the LF412. V OS ,

I B , and I OS are measured at V CM = 0.

Note 8: The LF412A is 100% tested to this specification. The LF412 is sample tested on a per amplifier basis to insure at least 85% of the amplifiers meet this speci-

fication.

Note 9: 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 pro-

duction test time, the input bias currents measured are correlated to junction temperature. In normal operation the junction temperature rises above the ambient tem-

perature as a result of internal power dissipation, P D .T j = T A +

T A £

70˚C and the military temperature range −55˚C

T A £

q jA P D where

q jA is 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 10: Supply voltage rejection ratio is measured for both supply magnitudes increasing or decreasing simultaneously in accordance with common practice. V S

= ± 6V to ± 15V.

Note 11: Refer to RETS412X for LF412MH and LF412MJ military specifications.

Note 12: 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 13: Human body model, 1.5 k

in series with 100 pF.

Typical Performance Characteristics

Input Bias Current

Supply Current

DS005656-10

DS005656-11

DS005656-12

Positive Common-Mode

Input Voltage Limit

Negative Common-Mode

Input Voltage Limit

Positive Current Limit

DS005656-15

DS005656-13

DS005656-14

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Note 6: These devices are available in both the commercial temperature range 0˚C

Typical Performance Characteristics (Continued)

Negative Current Limit

Output Voltage Swing

DS005656-16

DS005656-17

DS005656-18

Gain Bandwidth

Bode Plot

Slew Rate

DS005656-19

DS005656-20

DS005656-21

Distortion vs Frequency

Undistorted Output Voltage

Swing

Open Loop Frequency

Response

DS005656-22

DS005656-23

DS005656-24

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