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-
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
12
Ω
Uncommon Features
j
Extremely
fast settling
time to
0.01%
j
Fast slew
rate
j
Wide gain
bandwidth
j
Low input
noise
voltage
LF155/
LF355
2.5520MHz
201212
LF156/
LF356
41.51.5µs
51250V/µs
LF357
=5)
(A
V
Units
Simplified Schematic
DS005646-1
*
3 pF in LF357 series.
BI-FET™, BI-FET II™are trademarks of National Semiconductor Corporation.
If Military/Aerospace specified devices are required, contact the National Semiconductor Sales Office/Distributors for
availability and specifications.
LF155/6LF356BLF355/6/7
±
±
±
22V
40V
20V
Supply Voltage
Differential Input Voltage
Input Voltage Range (Note 2)
Output Short Circuit DurationContinuousContinuousContinuous
T
Settling Time to 0.01%(Note 7)41.51.5µs
Equivalent Input Noise
Voltage
RS=100Ω
f=100 Hz251515
=1,57.512V/µs
V
=550V/µs
V
2.5520MHz
f=1000 Hz201212
i
n
C
IN
Equivalent Input
Current Noise
f=100 Hz0.010.010.01
f=1000 Hz0.010.010.01
Input Capacitance333pF
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
T
A
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
LF155/156LF356BLF355/6/7
Supply Voltage, V
T
A
T
HIGH
and VOS,IBand IOSare measured at VCM=0.
Note 4: The Temperature Coefficient of the adjusted input offset voltage changes only 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, TJ. 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 temperature as a result of internal power dissipation, Pd. T
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 defined here, for a unity gain inverter connection using 2 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 2 kΩ and the output step is 10V (See Settling Time Test Circuit).
Note 8: Max. Power Dissipation is defined by the package characteristics. Operatingthe part near the Max. Power Dissipation may cause the part to operateoutside
guaranteed limits.
Pd where θJAis the thermal resistance from junction to ambient. Use of aheat sink is recommended
J=TA+θJA
Typical DC Performance Characteristics Curves are for LF155 and LF156 unless otherwise
specified.
LF155/LF156/LF355/LF356/LF357
V
=−5,
Input Bias Current
Input Bias Current
DS005646-37
Input Bias Current
DS005646-38
Voltage Swing
DS005646-39
www.national.com4
DS005646-40
Typical DC Performance Characteristics Curves are for LF155 and LF156 unless otherwise
specified. (Continued)
LF155/LF156/LF355/LF356/LF357
Supply Current
Negative Current Limit
DS005646-41
Supply Current
DS005646-42
Positive Current Limit
Positive Common-Mode
Input Voltage Limit
DS005646-43
DS005646-45
DS005646-44
Negative Common-Mode
Input Voltage Limit
DS005646-46
www.national.com5
Typical DC Performance Characteristics Curves are for LF155 and LF156 unless otherwise
specified. (Continued)
Open Loop Voltage Gain
LF155/LF156/LF355/LF356/LF357
DS005646-47
Typical AC Performance Characteristics
Gain Bandwidth
Output Voltage Swing
DS005646-48
Gain Bandwidth
DS005646-49
Normalized Slew Rate
DS005646-51
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DS005646-50
Output Impedance
DS005646-52
Typical AC Performance Characteristics (Continued)
LF155/LF156/LF355/LF356/LF357
Output Impedance
DS005646-53
LF156 Small Signal Pulse Response, AV=+1
LF155 Small Signal Pulse Response, AV=+1
DS005646-5
LF155 Large Signal Pulse Response, AV=+1
LF156 Large Signal Puls
Response, A
V
=+1
DS005646-6
DS005646-9
DS005646-8
Inverter Settling Time
DS005646-55
www.national.com7
Typical AC Performance Characteristics (Continued)
Inverter Settling Time
LF155/LF156/LF355/LF356/LF357
Bode Plot
DS005646-56
Open Loop Frequency Response
DS005646-57
Bode Plot
Bode Plot
DS005646-58
DS005646-60
DS005646-59
Common-Mode Rejection Ratio
DS005646-61
www.national.com8
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