CRDs – Constant Current Regulating Diodes

CRDs are current regulating diodes that help to maintain a constant current flow over a wide voltage range.  Constant current is supplied regardless of applied voltage fluctuations, load resistance changes and ripple voltage.

Our CRDs generally operate from 1V to 100V but higher voltages can be achieved by using a zener diode in series.  Higher current values can also be achieved by using the CRDs in parallel.

CRDs are especially useful where board-space is a premium and one CRD can readily replace several other devices providing the same constant current function.  Ip current values from 0.1mA to 22mA are readily available.


  • Constant current source for LED brightness stabilization
  • LED street lights, LED fluorescent lamps, LED light bulbs, LED downlights
  • Constant voltage circuit for supplying constant current to Zener diodes
  • Constant current source for proximity sensors and other sensors
  • Battery charger circuits
  • Constant current test equipment for various semiconductor devices
  • Telecommunications line interface
  • Earth leakage circuit breakers
  • Current source for piezoelectric actuators
  • Stabilized power supply circuits


  • Controls constant current from 0.1mA to 22mA
  • Available in SMD (SOD-123FL) or DO-35 diode packages
  • Operating temperature range:  -40° to 150°C
  • Can be used in parallel or in series with a zener diode

Stock Parts

S-101T, S-301T, S-501T, S-701T, S-102T, S-152T, S-202T, S-272T, S-352T, S-452T,

S-562T, S-822T, S-103T, S-123T, S-153T, S-183T, S-223T

ATC Semitec stocks a range of CRDs - a simple way of providing constant current for over a wide voltage range.