Index
Current Sources Page
- 40V current source operates from -40 to +85?C - wide-output-current range sources that accommodate a wide supply and temperature range, based on LM317 Rate this link
- Circuit forms novel floating current source - This novel floating current source represents an improved way to bias ISFET sensors. Rate this link
- Current source has high output impedance - composite 10-mA current-source configuration that has a compliance voltage of 5 to 42V, a set-current error of less than 1% and an output impedance of greater than 100 megaohms Rate this link
- Digital current source is nonvolatile - 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. This circuit is particularly suited for setting the drive current for the optical pump in widely tunable VCSELs (vertical-cavity surface-emitting lasers). Rate this link
- High-speed regulator makes great current source - bandwidth of this circuit measures more than 1 MHz, only the selected MOSFET and the ratings of the input supply's bypass capacitors limit the voltage compliance Rate this link
- L200 Regulator Circuit - easy to build a power supply with one single L200 IC, offers a variable current limit of up to 2 A, as well as voltage regulation Rate this link
- Precision current sink costs less than $20 - simple active load circuit for current from 1 mA to 1A and voltage from 3 to 40V Rate this link
- Programmable current source powers charger - digitally programmable current source capable of sourcing currents as high as 2.55A Rate this link
- Simple scheme keeps current drain constant - It is sometimes advantageous to keep the overall current consumption of an electronic device constant. This circuit outptu variable current to 5V load and maintains a constant current of approximately 102 mA in the power supply input. Rate this link
- Switching regulator forms constant-current source - When you need a high-current source, using a linear regulator is inadvisable, because of the high power dissipation in the series resistor. To solve the wasted-power problem, you can use a switch-mode regulator. This circuit uses an LM2576 adjustable regulator. It needs only a few external elements and has an adjustable sensing input, which you use for controlling the output current. Rate this link
- Variable 3 - 24 Volt / 3 Amp Power Supply - regulated power supply can be adjusted from 3 to 25 volts and is current limited Rate this link
- Variable Power Supply - based on versatile L200 voltage regulator, independent voltage (3-15V) and current (10mA-2A) limits Rate this link
- Voltage-to-current converter makes a flexible current reference - This voltage-to-current converter design can both source and sink current. The circuit is more flexible than some traditional current references that require different topologies for current sourcing and sinking. Also, you can easily adjust the value of the current reference by simply adjusting the circuit's input voltage. Rate this link
Current sources
Many applications require current sources rather than voltage sources. Current source provides a constant current to the output. This currentdoes not depend on the output voltage. An idea current source is a high output impedance device: it willsupply current, but does not show in other ways on the load circuit.When you need a low-current source, using a linear regulator isa typical approach. When you need a high-current source, using a linear regulator is inadvisable, because of the high power dissipation in the series resistor. To solve the wasted-power problem, you can use a switch-mode regulator. In some applications current signal sources are needed for measurement purposes. One very easy trick is to insert a large value resistor (compared to the impedance of the circuit measured) in series with the generator. This willessentially convert your constant voltage generator to a constantcurrent source. This is not completely ideal current source, butgood enough approximation for most applications, where the load resistance is much smaller than the current limiting resistor resistance.
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