ANALOG DEVICES

iCoupler® Digital Isolation - Unparalleled Performance and Integration

iCoupler technology is based on chip-scale transformers rather than the LEDs and photodiodes used in optocouplers. By fabricating the transformers directly on-chip using wafer-level processing. iCoupler channels can be integrated with each other and other semiconductor functions at low cost. iCoupler transformers are planar structures that use the CMOS metal layers as well as a gold layer fabricated on top of the wafer passivation. A high breakdown polyimide layer underneath the gold layer insulates the top transformer coil from the bottom. CMOS circuits connected to the top coil and bottom coil provide the interface between each transformer and its external signals.

Input logic transitions are encoded using 1 ns pulses routed to the primary side of a given transformer. These pulses couple from one transformer coil to another and are detected by the circuitry on the secondary side of the transformer. This circuitry then recreates the input digital signal at the output. In addition, a refresh ciruit is included at the input side to ensure hat the output state matches the input state even if no input transitions are present. This is important in power-up situations as well as input waveforms with low data rates or long durations with constant dc inputs.

Since the purpose of iCoupler products is to isolate an input from an output, the circuitry on one side of the transformer must be contained on a separate chip from the circuitry on the second side fo the transformers. The transformers themselves can be placed on either chip or on a third chip as shown in the ADuM140x configuration below. The entire chipset is assembled within a standard plastic package similar to that used for a wide variety of semiconductor devices.

A novel feature of iCoupler devices is their ability to combine both transmit and receive channels in the same package. Since the iCoupler transformers are inherently bidirectional, signals can pass in either direction, provided the appropriate circuitry is present on either side of the transformers. In this manner, multi-channel isolators are offered with a variety of transmit/receive channel configurations.

Another novel feature of the iCoupler technology is that the transformer coils that are used to isolate data signals may also be used as transformers in an isolated DC-DC converter. That allows both data and power isolation to be integrated into a single package, as is done on the ADuM524x family of iCoupler products.

The flexibility and scalability of iCoupler technology will continue to produce new innovations in isolation. Please come back to this site for updates on new products.