National Semiconductor LF155, LF156, LF256, LF257, LF355 Technical data

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LF155/LF156/LF256/LF257/LF355/LF356/LF357 JFET Input Operational Amplifiers

General Description

These are the first monolithic JFET input operational amplifiers to incorporate well matched, high voltage JFETs on the same chip with standard bipolar transistors (BI-FET nology). These amplifiers feature low input bias and offset currents/low offset voltage and offset voltage drift, coupled with offset adjust which does not degrade drift or common-mode rejection. The devices are also designed for high slew rate, wide bandwidth, extremely fast settling time, low voltage and current noise and a low 1/f noise corner.

™

Tech-

Features

Advantages

n Replace expensive hybrid and module FET op amps n Rugged JFETs allow blow-out free handling compared

with MOSFET input devices

n Excellent for low noise applications using either high or

low source impedance—very low 1/f corner

n Offset adjust does not degrade drift or common-mode

rejection as in most monolithic amplifiers

n New output stage allows use of large capacitive loads

(5,000 pF) without stability problems

n Internal compensation and large differential input voltage

capability

Applications

n Precision high speed integrators n Fast D/A and A/D converters n High impedance buffers n Wideband, low noise, low drift amplifiers

n Logarithmic amplifiers n Photocell amplifiers n Sample and Hold circuits

Common Features

n Low input bias current: 30pA n Low Input Offset Current: 3pA n High input impedance: 10 n Low input noise current:

n High common-mode rejection ratio: 100 dB n Large dc voltage gain: 106 dB

Uncommon Features

LF155/

LF355

Extremely fast settling time to

0.01%

Fast slew rate

Wide gain bandwidth

Low input noise voltage

December 2001

Ω

LF156/ LF256/

LF356

4 1.5 1.5 µs

5 12 50 V/µs

2.5 5 20 MHz

20 12 12

LF257/

LF357

Units

=5)

LF155/LF156/LF256/LF257/LF355/LF356/LF357 JFET Input Operational Amplifiers

Simplified Schematic

3pF in LF357 series.

BI-FET™, BI-FET II™are trademarks of National Semiconductor Corporation.

00564601

Absolute Maximum Ratings (Note 1)

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

LF155/6 LF256/7/LF356B LF355/6/7

Supply Voltage Differential Input Voltage Input Voltage Range (Note 2) Output Short Circuit Duration Continuous Continuous Continuous T

JMAX

H-Package 150˚C 115˚C 115˚C N-Package 100˚C 100˚C M-Package 100˚C 100˚C

Power Dissipation at T

= 25˚C (Notes

1, 8)

H-Package (Still Air) 560 mW 400 mW 400 mW

LF155/LF156/LF256/LF257/LF355/LF356/LF357

H-Package (400 LF/Min Air Flow) 1200 mW 1000 mW 1000 mW N-Package 670 mW 670 mW M-Package 380 mW 380 mW

Thermal Resistance (Typical) θ

H-Package (Still Air) 160˚C/W 160˚C/W 160˚C/W H-Package (400 LF/Min Air Flow) 65˚C/W 65˚C/W 65˚C/W N-Package 130˚C/W 130˚C/W M-Package 195˚C/W 195˚C/W

(Typical) θ

H-Package 23˚C/W 23˚C/W 23˚C/W Storage Temperature Range −65˚C to +150˚C −65˚C to +150˚C −65˚C to +150˚C Soldering Information (Lead Temp.)

Metal Can Package

Soldering (10 sec.) 300˚C 300˚C 300˚C

Dual-In-Line Package

Soldering (10 sec.) 260˚C 260˚C 260˚C

Small Outline Package

Vapor Phase (60 sec.) 215˚C 215˚C Infrared (15 sec.) 220˚C 220˚C

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

ESD tolerance

(100 pF discharged through 1.5kΩ) 1000V 1000V 1000V

± ± ±

22V 40V 20V

± ± ±

22V 40V 20V

± ± ±

18V 30V 16V

DC Electrical Characteristics

(Note 3)

Symbol Parameter Conditions

Min Typ Max Min Typ Max Min Typ Max

∆V

∆TC/∆V

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Input Offset Voltage RS=50Ω,TA=25˚C 3 5 3 5 3 10 mV

Over Temperature 7 6.5 13 mV

/∆T Average TC of Input

RS=50Ω

Offset Voltage Change in Average TC

Adjust

with V

=50Ω, (Note 4)

Input Offset Current TJ=25˚C, (Notes 3, 5) 3 20 3 20 3 50 pA

J≤THIGH

LF155/6

LF256/7 LF356B

LF355/6/7

5 5 5 µV/˚C

0.5 0.5 0.5

20 1 2 nA

Units

µV/˚C

per mV

DC Electrical Characteristics (Continued)

(Note 3)

Symbol Parameter Conditions

VOL

Input Bias Current TJ=25˚C, (Notes 3, 5) 30 100 30 100 30 200 pA

J≤THIGH

Input Resistance TJ=25˚C 10 Large Signal Voltage

Gain

VS=±15V, TA=25˚C 50 200 50 200 25 200 V/mV V

=±10V, RL=2k

Over Temperature 25 25 15 V/mV

Output Voltage Swing VS=±15V, RL=10k

=±15V, RL=2k

Input Common-Mode

VS=±15V

Voltage Range

CMRR Common-Mode

Rejection Ratio

PSRR Supply Voltage

(Note 6)

Rejection Ratio

DC Electrical Characteristics

TA=TJ= 25˚C, VS=±15V

Parameter

Supply Current

LF155 LF355 LF156/256/257/356B LF356 LF357

Typ Max Typ Max Typ Max Typ Max Typ Max

2424 5 7 510510mA

LF155/6

LF256/7 LF356B

LF355/6/7

Units

Min Typ Max Min Typ Max Min Typ Max

50 5 8 nA

12±13

±10± ±

+15.1

−12 −12 −12 V

± ±

12±13 10±12

15.1

± ±

+10

12±13 V 10±12 V

+15.1 V

85 100 85 100 80 100 dB

Units

LF155/LF156/LF256/LF257/LF355/LF356/LF357

Ω

AC Electrical Characteristics

TA=TJ= 25˚C, VS=±15V

Symbol Parameter Conditions

LF155/355 LF156/256/

356B

LF156/256/356/

LF356B

LF257/357

Units

Typ Min Typ Typ

SR Slew Rate LF155/6:

=1,

LF357: A

=5 50 V/µs

5 7.5 12 V/µs

GBW Gain Bandwidth Product 2.5 5 20 MHz t

Settling Time to 0.01% (Note 7) 4 1.5 1.5 µs Equivalent Input Noise

Voltage

RS=100Ω f=100 Hz 25 15 15

f=1000 Hz 20 12 12

Equivalent Input Current Noise

f=100 Hz 0.01 0.01 0.01 f=1000 Hz 0.01 0.01 0.01

Input Capacitance 3 3 3 pF

Notes for Electrical Characteristics

Note 1: The maximum power dissipation for these devices must be derated at elevated temperatures and is dictated by T

. The maximum available power dissipation at any temperature is PD=(T

Note 2: Unless otherwise specified the absolute maximum negative input voltage is equal to the negative power supply voltage. Note 3: Unless otherwise stated, these test conditions apply:

JMAX−TA

)/θJAor the 25˚C P

, whichever is less.

dMAX

, θJA, and the ambient temperature,

JMAX

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Notes for Electrical Characteristics (Continued)

LF155/156 LF256/257 LF356B LF355/6/7

Supply Voltage, V T

HIGH

and VOS,IBand IOSare measured at VCM=0. Note 4: The Temperature Coefficient of the adjusted input offset voltage changesonly a small amount(0.5µV/˚C typically) for each mV of adjustment from its original

unadjusted value. Common-mode rejection and open loop voltage gain are also unaffected by offset adjustment. Note 5: 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, Pd. T recommended if input bias current is to be kept to a minimum.

Note 6: Supply Voltage Rejection is measured for both supply magnitudes increasing or decreasing simultaneously, in accordance with common practice. Note 7: Settling time is definedhere, for a unity gain inverter connection using2 kΩ resistors for the LF155/6. It is the time required for the error voltage (the voltage

at the inverting input pin on the amplifier) to settle to within 0.01% of its final value from the time a 10V step input is applied to the inverter. For the LF357, A the feedback resistor from output to input is 2kΩ and the output step is 10V (See Settling Time Test Circuit).

Note 8: Max. PowerDissipation is defined bythe package characteristics. Operatingthe part near theMax. Power Dissipation may cause the part to operate outside guaranteed limits.

15V ≤ VS≤±20V

−55˚C ≤ TA≤ +125˚C −25˚C ≤ TA≤ +85˚C 0˚C ≤ TA≤ +70˚C 0˚C ≤ TA≤ +70˚C +125˚C +85˚C +70˚C +70˚C

J=TA+θJA

15V ≤ VS≤±20V

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

15V ≤ V

20V VS=±15V

LF155/LF156/LF256/LF257/LF355/LF356/LF357

Typical DC Performance Characteristics Curves are for LF155 and LF156 unless otherwise

specified.

Input Bias Current Input Bias Current

. Due to limited

= −5,

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Input Bias Current Voltage Swing

00564639

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00564638

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Typical DC Performance Characteristics Curves are for LF155 and LF156 unless otherwise

specified. (Continued)

Supply Current Supply Current

LF155/LF156/LF256/LF257/LF355/LF356/LF357

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Negative Current Limit Positive Current Limit

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Positive Common-Mode

Input Voltage Limit

Negative Common-Mode

Input Voltage Limit

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Typical DC Performance Characteristics Curves are for LF155 and LF156 unless otherwise

specified. (Continued)

Open Loop Voltage Gain Output Voltage Swing

LF155/LF156/LF256/LF257/LF355/LF356/LF357

00564647

Typical AC Performance Characteristics

Gain Bandwidth Gain Bandwidth

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Normalized Slew Rate Output Impedance

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00564651

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00564652

Typical AC Performance Characteristics (Continued)

LF155/LF156/LF256/LF257/LF355/LF356/LF357

Output Impedance LF155 Small Signal Pulse Response, A

00564653

00564605

=+1

LF156 Small Signal Pulse Response, AV= +1 LF155 Large Signal Pulse Response, AV=+1

LF156 Large Signal Puls

Response, A

= +1 Inverter Settling Time

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