Datasheet 搜索 > 运算放大器 > TI（德州仪器） > LM6142AMJ-QML 数据手册 > LM6142AMJ-QML 开发手册 1/12 页
器件3D模型￥ 1348.815
LM6142AMJ-QML 开发手册 - TI（德州仪器）
制造商:
TI（德州仪器）
分类:
运算放大器
封装:
CDIP
Pictures:
3D模型
符号图
焊盘图
引脚图
产品图
LM6142AMJ-QML数据手册
Page:
of 12 Go
若手册格式错乱，请下载阅览PDF原文件
A Comprehensive Study of
the Howland Current Pump
National Semiconductor
Application Note 1515
Robert A. Pease
January 29, 2008
A Comprehensive Study
It is well known to analog experts that you can use the positive
and negative inputs of an operational amplifier to make a high-
impedance current source (current pump) using a conven-
tional operational amplifier (op amp). This basic circuit can put
out both + and - output current (or zero current) into various
loads. The theory is simple. But the practical problems in-
volved are not so simple or obvious.
There are two basic circuits -- the Basic Howland Current
Pump, Figure 1, and the "Improved" Howland Current Pump.
The Basic circuit does good service for simple applications,
but if its weaknesses are unacceptable, the "Improved" circuit
may do much better for critical tasks. See Figure 5.
20203801
FIGURE 1. The Basic Howland Current Pump
Applications for the Howland
Current Pump
Sometimes a unidirectional current source (or sink) is just
right. It is easy to make them with high output impedance and
wide range, using an op-amp and some Darlington-connect-
ed transistors. But sometimes you need a current pump that
can put out a current in either direction – or even AC currents.
The Howland current pump is usually excellent for that. Cur-
rent sources are often used for testing other devices. They
can be used to force currents into sensors or other materials.
They can be used in experiments, or in production test. They
can bias up diodes or transistors, or set test conditions. When
you need them, they are useful — even if you only need them
once or twice a year.
© 2008 National Semiconductor Corporation 202038 www.national.com
A Comprehensive Study of the Howland Current Pump AN-1515
器件 Datasheet 文档搜索
AiEMA 数据库涵盖高达 72,405,303 个元件的数据手册，每天更新 5,000 多个 PDF 文件
