National LF155, LF156, LF256, LF257, LF355, LF356, LF357 JFET Input Operational Amplifiers Data Manual
Summary
These advanced JFET input operational amplifiers are designed for high-precision and low-noise instrumentation systems. The manual provides comprehensive technical data covering electrical characteristics, optimal operating conditions, and key advantages such as ultralow input bias current, high common-mode rejection, and fast bandwidth. They are ideal for electronics engineers requiring robust performance in specialized circuits, including integrators, sample-and-hold units, or wideband signal conditioning applications.
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LF155/LF156/LF256/LF257/LF355/LF356/LF357 JFE Input perational A plifiers
LF155/LF156/LF256/LF257/LF355/LF356/LF357 JFET Input Operational Amplifiers
Logarithmic amplifiers
General Description
Photocell amplifiers
These are the first monolithic JFET input operational ampli-
Sample and Hold circuits
fiers to incorporate well matched, high voltage JFETs on the
same chip with standard bipolar transistors (BI-FET™ Tech- Common Features
nology). These amplifiers feature low input bias and offset Low input bias current: 30p A currents/low offset voltage and offset voltage drift, coupled Low Input Offset Current: 3p A with offset adjust which does not degrade drift or
High input impedance: 1012Ω
common-mode rejection. The devices are also designed for
Low input noise current:
high slew rate, wide bandwidth, extremely fast settling time,
High common-mode rejection ratio: d B
low voltage and current noise and low 1/f noise corner.
Large dc voltage gain: d B
Features
Uncommon Features
Advantages Replace expensive hybrid and module FET op amps LF155/ LF156/ LF257/ Units Rugged JFETs allow blow-out free handling compared
LF355 LF256/ LF357
with MOSFET input devices
LF356 (AV=5)
Excellent for low noise applications using either high or
Extremely 1.5 1.5 µs
low source impedance very low 1/f corner
fast settling
Offset adjust does not degrade drift or common-mode
rejection as in most monolithic amplifiers time to New output stage allows use of large capacitive loads 0.01%
(5,000 p F) without stability problems Fast slew V/µs Internal compensation and large differential input voltage
capability
Wide gain 2.5 MHz bandwidth
Applications
Low input
Precision high speed integrators
noise
Fast D/A and A/D converters
voltage
High impedance buffers Wideband, low noise, low drift amplifiers
Simplified Schematic
*3p F in LF357 series.
BI-FET™, BI-FET II™ are trademarks of National Semiconductor Corporation.
National Semiconductor Corporation DS005646 www.national.com
Page Summary Contents For National LF155, LF156, LF256, LF257, LF355, LF356, LF357 JFET Input Operational Amplifiers Data Manual
Manual Details
| Brand | National |
|---|---|
| Pages | 23 |
| File Size | 1.04 MB |
| Published | June 01, 2026 |
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Frequently Asked Questions
What is the main advantage of using BI-FET Technology in these amplifiers?
It integrates well matched high voltage JFETs and standard bipolar transistors onto a single chip, providing low input bias currents.
What is the typical Common-Mode Rejection Ratio (CMRR)?
The specified CMRR is typically 100 dB for most listed devices.
Are these chips suitable for critical life support medical equipment?
No. They are not authorized for use as critical components in life support systems without expressed written approval from National Semiconductor Corporation.