ATC Semitec Current Limiting Diodes (CRDs) – ATC Semitec E-452~E-562, Current regulating diode from ATC Semitec which regulates current in the same way as a Zener diode regulates voltage.Applications include current regulation, limiting, biasing, stabilising and voltage reference. ATC Semitec E-452~E-562 Current Limiting Diode CRD – 4.5mA