Because noise current as low as .25mA may cause the LED to illuminate dimly in the off state, DDP® LEDs are available with an optional built-in shunt resistor to bleed-off residual current. There are several sources of leakage current in a circuit. Transient voltage from a relay or discharge from a capacitor creates circuit noise. Also, inherent in the design of some programmable logic controllers (PLCs), is a triac protective circuit that may supply up to 5mA of leakage current in the off state.
