DEAD BAND CIRCUITS USING CURRENT REFERENCE....... 14
BIDIRECTIONAL CURRENT SOURCES ....................................16
LIMITING CIRCUITS USING
BIDIRECTIONAL CURRENT SOURCES ....................................16
PRECISION TRIANGLE WAVEFORM GENERATOR
USING BIDIRECTIONAL CURRENT SOURCES .......................17
DUTY CYCLE MODULATOR USING
BIDIRECTIONAL CURRENT SOURCES ....................................17
SLEW RATE LIMITER ................................................................ 18
SINGLE SUPPLY INSTRUMENTATION AMPLIFIER ................18
VOLTAGE CONTROLLED CURRENT SOURCES
VOLTAGE CONTROLLED
CURRENT SOURCE USING INA105 ..........................................18
VOLTAGE CONTROLLED CURRENT SOURCE WITH
INSTRUMENTATION AMPLIFIER INPUT—THE XTR101 ......... 20
SINGLE SUPPLY VOLTAGE
CONTROLLED CURRENT SOURCE—THE XTR110 ................ 20
CURRENT-TO-VOLTAGE
CONVERTERS, AND CURRENT RECEIVERS
CURRENT RECEIVER WITH COMPLIANCE TO
BOTH POWER SUPPLY RAILS USING THE INA105 ............. 22
POWER AMP LOAD CURRENT
MONITORING USING THE INA105 OR THE INA117 ............... 22
4 to 20mA CURRENT LOOP RECEIVER
WITH 0 to 5V OUTPUT USES THE RCV420 ............................. 23
VIRTUAL GROUND CURRENT
TO VOLTAGE CONVERTER .......................................................23
PHOTODIODE AMPLIFIERS .......................................................23
GLOSSARY ............................................................. 27
This is not an exhaustive collection of circuits, but a com-
pendium of preferred ones. Where appropriate, suggested
part numbers and component values are given. Where added
components may be needed for stability, they are shown.
Experienced designers may elect to omit these components
in some applications, but less seasoned practitioners will be
able to put together a working circuit free from the frustra-
tion of how to make it stable.
The applications shown are intended to inspire the imagina-
tion of designers who will move beyond the scope of this
work.
CONTENTS
DESIGN OF FIXED CURRENT SOURCES
REF200 IC CURRENT SOURCE
DESCRIPTION PIN STRAPPING REF200 FOR 50µA—400µA..2
RESISTOR PROGRAMMABLE CURRENT SOURCES
AND SINKS USING REF200 AND ONE EXTERNAL OP AMP:
Current Source or Sink With Compliance to
Power Supply Rail and Current Out >100
µA .......................... 4
Current Source or Sink With Any Current Out ...................... 5
Floating Current Source With Current Out >100
µA............... 5
Current Sources made with Voltage References................... 5
Current Sources and Sinks and Current Mirrors
Using an Amplifier and a Series Pass Element.................... 6
Floating Current Source With
Current Out >100
µA and No Separate Power Supply ........... 6
CASCODING CURRENT SOURCES
FOR IMPROVED OUTPUT IMPEDANCE,
HIGH FREQUENCY PERFORMANCE,
AND HIGH VOLTAGE COMPLIANCE:
Cascoding with FETs ................................................................ 8
200
µA Floating Cascoded Current Source Using REF200 ... 9
300µA Floating Cascoded Current Source Using REF200 . 10
400µA Floating Cascoded Current Source Using REF200 . 10
NOISE REDUCTION OF CURRENT SOURCES ........................ 10
APPLICATIONS OF FIXED CURRENT SOURCES
VOLTAGE REFERENCES USING CURRENT SOURCES ........ 11
OP AMP OFFSET
ADJUSTMENT USING 5mV REFERENCE.................................12
WINDOW COMPARATOR USING
FLOATING VOLTAGE REFERENCE ..........................................13
RTD EXCITATION USING CURRENT REFERENCE................. 13
IMPLEMENTATION AND APPLICATIONS OF
CURRENT SOURCES AND CURRENT RECEIVERS
R. Mark Stitt (602) 746-7445
This application guide is intended as a source book for the
design and application of:
● Current sources
● Current sinks
● Floating current sources
● Voltage-to-current converters
(transconductance amplifiers)
● Current-to-current converters (current mirrors)
● Current-to-voltage converters
(transimpedance amplifiers)
APPLICATION BULLETIN
®
Mailing Address: PO Box 11400 • Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd. • Tucson, AZ 85706
Tel: (602) 746-1111 • Twx: 910-952-111 • Telex: 066-6491 • FAX (602) 889-1510 • Immediate Product Info: (800) 548-6132
©
1989 Burr-Brown Corporation AB165 Printed in U.S.A. March, 1990
SBOA046
