To transfer data across the isolation barrier, iCoupler digital isolators encode data into short, 1ns pulses. Two consecutive pulses indicate a leading edge and a single pulse indicates a falling edge. A receiver circuit decodes these pulses and recreates the rising and falling edges on the secondary side. This type of narrow pulse encoding scheme in CMOS uses up to an order of magnitude less power than optocouplers which are continuously using power while the LED is on. For data integrity and noise immunity, all iCoupler products use an input glitch filter to reduce the harmful effects of any noisy input signal line. Analog Devices iCoupler digital isolators all implement a refresh circuit that resends the last data pulse if no new data is present within one µs. This provides DC correctness at start up and is guarantees data error correction within 1µs. The iCoupler products also integrate a fail-safe feature that ensures that the output is in a safe default state if the power on the input side goes down. A watch dog timer on the output side will put the output into the safe default state, if no new data or refresh pulses are detected across the isolation barrier within the 3µs time out period. Each product comes with a default output state, either fixed or selectable, to protect any down stream circuitry from erroneous states that could cause damage.