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Constant Current Circuits

#'s - C       DQ      R - S

Last Updated: December 31, 2017 06:47 AM

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DAC & flip-flops form constant-current-source -  23-Apr-09 EDN-Design Ideas Using two flip flops, you can program a serial-input DAC to produce a constant 4 mA__ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

DAC Controlled 100mA Current Source -  The LT3092 easily interfaces with an external DAC to allow digital current control. __ Linear Technology/Analog Devices App Note, Mar 24th 2010

Digital current-source is nonvolatile -  02/07/02  EDN-Design Ideas Digitally programmable current sources that feature automatic trimming and retain the setting despite power-down cycles are useful in applications such as RF- and laser-communications drivers.  The circuit in Figure 1, for example, i__ Circuit Design by Stephen Woodward, University of North Carolina, Chapel Hill

Dual Constant-Current Load Tests Low-Current Power Supplies -  06/07/07 EDN-Design Ideas You can use a simple 9V-battery-powered constant-current load to test small power supplies at various loads.  Today’s small electronic appliances, such as washers, dryers, and stoves, use switched-mode power supplies to replace bulky, heavy, linear-power supplies.  The engineer testing these power supplies, which range in current from 50 mA to 1A, typically uses resistors or standard off-the-shelf electronic loads.  An engineer would employ a variety of high-wattage resistors to verify multiple loading conditions to satisfy a proper design.  Most off-the-shelf electronic loads target an average of 300W.  When measuring 50 to 300 mA, a display is inaccurate; most of them display 0.1A, but accuracy is questionable at that low range.  You can alternatively use the simple dual constant-current-load design in Figure 1, which you can build with inexpensive, common parts.  __ Circuit Design by John Lo

Form Constant-Current SCR -  02/01/01 EDN-Design Ideas A typical SCR (silicon-controlled rectifier) requires a trigger current, which causes the SCR structure to latch on.  Once the device latches, the current through the SCR is solely a function of external component values.  The SCR has no inherent ability to limit the current flow once it latches on.  Current continues to flow, as long as the current exceeds a minimal value known as the holding current.  The circuit in Figure 1 is similar to an SCR, because it also requires a trigger current to latch into its on state.   __ Circuit Design by Robert Buono, Ringwood, NJ

Ground Referred Precision Current Sources -  The zero drift LTC2054 instrumentation amplifier can be used in conjunction with one of Linear Technology's precision, low temperature drift shunt voltage references (in this example the LT1634) to create a precision, ground referred current source. __ Linear Technology/Analog Devices App Note, Mar 30th 2010

Ground Resistance Tester -  UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0.1ohms.    This resistance must be tested with actual line current in excess or 10 amps.    The circuit shown uses a couple of LEDs to indicat . . . Hobby Circuit designed by Dave Johnson P.E.-April, 2001

High Accuracy 10mA Current Source -  An external reference improves the initial accuracy and temperature drift of the LT3092 current source. __ Linear Technology/Analog Devices App Note, Mar 24th 2010

High Voltage 100mA Current Source -  An external zener diodes protects the LT3092 and allows the part to be used in high voltage applications. __ Linear Technology/Analog Devices App Note, Mar 24th 2010

IC Current Sources-LT3092 -  Current sources have been a well known but theoretical circuit component.  Unlike voltage sources, a 0.01% accurate 2-terminal current source has been an elusive component that is not easily available and difficult to design.  With the introduction of the LT3092, the current source as a drop-in component becomes a reality.  The __ Linear Technology/Analog Devices App Note, Robert Dobkin-Vice President-Engineering and Chief Technical Officer Sep 15th 2009

LED Driver using Constant Current -  LEDs are current driven devices.  The light they produce is proportional to the current flowing though them.  One way to maintain a fairly steady light output is to keep the current through the LED fixed, even as the supply voltage may change.  A classic. . . Circuit by Dave Johnson P.E.-December, 2010

LT1511 Low Dropout Constant-Current/Constant-Voltage 3a Battery Charger -  DN144 Design Notes___ Linear Technology/Analog Devices

NMH/NiCd 6v Battery Tester -  I designed this circuit to test rechargeable six volt battery packs under constant current conditions.  As designed, the circuit applies a 10 amp load to the battery pack.  A heat sink must be used on the main power transistor . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2004

Novel Floating Current Source -  05/01/03  EDN-Design Ideas One-shot provIdeas frequency discriminationFigure 1 shows a polarization circuit applicable to ISFET (ion-sensitive field-effect-transistor] sensors.  ISFETs are solid-state chemical sensors that measure the pH value of a solution i__ Circuit Design by S Casans, AE Navarro, and D Ramirez, University of Valencia, Burjassot, Spain

One Amp Current Injector -  I designed and built this thing many years ago.  I published the hobby circuit in the now defunct Radio Elecronics magazine back in 1992.  The electronic circuit injects a precise 1 amp of current into any unknown resistor, up to about two ohms.  Two alkaline . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Op Amp can source or sink current -  03/02/06 EDN-Design Ideas   Bipolar current source beats familiar Howland-current pump__ Circuit Design by Alfredo H Saab and Steve Logan, Maxim Integrated Products Inc,  Sunnyvale, CA; Edited by Brad Thompson and Fran GranvilleMarch 2, 2006

Parallel Current Sources for Higher Current 300mA Output -  The LT3092 can easily be paralleled for higher current outputs __ Linear Technology/Analog Devices App Note, Mar 24th 2010

Precision Current Source -  A non-inverting amplifier configuration can force an input control voltage across a ground referred resistor.  This creates a precise amount of current flow.  This current must be sunk by the external transitors so the same amount of current flows from ground and sourced to a negative supply referred load circuit. __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Precision Ground Referenced Voltage Controlled Current Source -  The control voltage, Vin, is converted to a charge on a capacitor that is referenced to ground.  This charge is transferred to place a differential voltage across the output current programming resistor.  The output current then flows into a ground referenced load for a precision single supply circuit without the need for a voltage __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Precision Nanoamp Bidirectional Current Source -  This circuit sources and sinks just nanoamps of current with precision due to the low input bias current of the CMOS op amps.  A buffered difference amplifier and an integrator force the voltage across a 10Megaohm set resistor to be 1/1000 of the control input voltage in either polarity. __ Linear Technology/Analog Devices App Note, Mar 16th 2010

Precision programmable current source uses two ICs -  EDN-Design Ideas 11/20/2015    Here are some programmable current source Design Ideaswhich make good use of precision on-chip component matching__ Circuit Design by Stefano Salvatori & Pietro Oliva

Precision Voltage Controlled Current Source -  The ultra-precise LTC2053 instrumentation amplifier is configured to servo the voltage drop on sense resistor R to match the command VC.  The LTC2053 output capability limits this basic configuration to low current applications. __ Linear Technology/Analog Devices App Note, Mar 31, 2010

Programmable Switching 1.5A Current Source -  The LTC3600 is a high efficiency, monolithic synchronous buck regulator whose output is programmed with just one external resistor.  The accurate internally generated 50μA current source on the ISET pin allows the use of a single external resistor to program an output voltage that ranges from 0V to 0.5V below VIN.  The VOUT __ Linear Technology/Analog Devices App Note, Jan 16th 2012

Provide constant-current load for testing batteries -  02/19/09  EDN-Design Ideas A 9V battery provIdeas power for a constant-current source for testing AA- or AAA-size batteries__ Circuit Design by Vladimir Rentyuk, Modul-98 Ltd, Zaporozhye, Ukraine

Provides Efficient Fan-Speed Control -  03/04/04  EDN-Design Ideas As Moore's Law plunges us into the realm of multigigahertz processors and PCs with gigabytes of RAM, engineers face the task of removing the heat that these state-of-the-art components produce.  Cooling such systems poses a dilemma.  __ Circuit Design by John Guy, Maxim Integrated Products, Sunnyvale, CA

Provides Motor Feed Control -  07/25/02 EDN-Design Ideas Linear power driver works from single supplyBecause we needed a small grinding machine, we modified an old milling machine that lacked a control system.  The table of the grinding machine needed only to move back and forth with__ Circuit Design by Jean-Bernard Guiot, DCS AG, Allschwil, Switzerland

Constant Current Circuits:  #'s - C       DQ      R - S

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