CRDs - Constant Current Diodes

Semitec’s range of CRD Current Regulating Diodes (sometimes called current limiting diodes or constant current diodes) offers a very simple way of providing constant current over a wide voltage range.  They offer protection, stability and control when driving LEDs, optocouplers & battery-charging circuits.

Over a wide voltage range from 1V to 100V, Semitec CRDs can stabilise a current at a fixed value.  By using a single constant current diode in your circuit, voltage changes, load resistance changes or ripple voltage effects will not affect the through current value.  Recreating a constant current circuit such as this would require several components whereas using a Semitec CRD you only need one simple part to achieve the same result.

This offers the advantage of simplifying product assembly and minimises the component count, particularly useful in space critical applications where board space is a premium.  SMD stock parts include the following;

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


  • LED brightness stabilisation
  • LED street lights, light bulbs and downlighters
  • Constant voltage/current circuits for Zener diodes
  • Constant current source for proximity and other sensors
  • Battery charging/discharge circuits
  • DC-DC converters

For further technical information, see our Frequently Asked Questions section

Call us today on 01606 871680 or complete the Contact us form, to discuss your application’s thermal sensor requirements.  Using our extensive technical knowledge and innovative supplier base, we will work with you to provide the optimum solution for your product.

  • Products
  • FAQs
  • CRD Constant Current Diodes

    CRDs are current regulating diodes (or constant current diodes) that help to maintain a fixed current value over a wide voltage range.

    • Constant current values from 0.1mA to 22mA
    • Operating temperature range:  -40°C to 150°C
    • Can be used in parallel or in series with Zener diodes