Constant current
A constant current (steady current, time-independent current, stationary current) is a type of direct current (DC) that does not change its intensity with time.
Sources
If the load is constant, a steady current can be obtained via a constant voltage source. If the load is varying, a steady current can be obtained via a constant current supply source.
Constant voltage sources
An
battery consists of two or more cells, connected in either parallel or series pattern.[1]
A
electrical generator comprising an electrically conductive disc or cylinder rotating in a plane perpendicular to a uniform static magnetic field. A magnetohydrodynamic generator
directly extracts electric power from moving hot gases through a magnetic field, without the use of rotating electromagnetic machinery.
AC generators can be used as sources of steady current with a rectifier and a good ripple filter. Pulsed DC generators can be used as sources of steady current with a good ripple filter.
Constant current power supplies
In
current regulator and must appear to the component as a current source
of suitable reliability.
An important usage of constant current
series resistance
is sufficient to light an LED, sometimes the design needs to guard against high current (or risk burning out the LEDs).
Another use is in
electrical resistance and are optimally operated within a short range of currents. [2] Other uses include shielded metal arc welding and gas tungsten arc welding.[3]
Constant Current Source Applications for LEDs
- Reliability Testing
- Device Burn-in Test
- HASS and IESNA LM-80 Applications
- Energy Star Certification
- Calibration Lamp Drive
- DC Driven Lamps
- Resistor Aging
- Laser Diode DC Drive[4]
See also
References
- ^ "Electrochemical Cells".
- ^ Caladen Circuit Corner, before Sep 5 2009, LED Current Controller Archived 2005-01-13 at archive.today
- ^ "CONSTANT VOLTAGE POWER SOURCE". American Welding Society. Retrieved 2021-09-17.
- ^ "SpikeSafe DC Current Sources - Vektrex". Vektrex. Retrieved 2017-08-28.