IsoLoop is the trademark name for NVE's family of isolation products. IsoLoop devices are created from the combination of micro-machined coils fabricated over resistors made from giant magnetoresistive materials, or GMR. Highly dense, multichannel, isolated interfaces can be fabricated when this semiconductor based isolation structure process is combined on-chip with integrated circuits.
The IsoLoop's unique resistors are fabricated from a thin film GMR material that has a bi-stable resistance value. Figure 1 illustrates that a current flowing through the on-chip coil generates a magnetic field. A change in the direction of the current switches the state of the GMR resistor bridge between its high and low value to create a logic 1 or 0. Power consumption is minimised because the IsoLoop requires a very short current pulse (~2 ns) to alter the resistor state.
The integrated 'building block' IsoLoop structure cross section illustrated in Figure 2 includes a shield that protects the resistor bridge from external fields and also serves to concentrate the magnetic flux created by the coil current. This building block isolator is then used to build a wide range of standard isolated logic functions using a special packaging technique.
Advantages
In high-speed data transmission systems, data integrity can only be maintained where there is low pulse width distortion. The IsoLoop family of products has a 2 ns pulse width distortion specification giving them an unsurpassed performance advantage in this category. Propagation delays are less than 10 ns and propagation delay skews are 2 ns.
True logic functions are achieved in almost the same sized packages as the original non-isolated logic function, without the need for extra surrounding components required to complete the desired function. Only two additional power supply pins, needed on the isolated side, add to the total pin count.
Small size, high performance, and low cost make IsoLoop technology highly versatile and adaptable for isolation applications.
Applications
IL710, IL485 and IL485W are for PROFIBUS applications. The IL422 full-duplex transceiver provides the same performance as the IL485 (low distortion and low propagation delay). The IL485 has 35 Mbaud transmission capability and the IL422 has 25 Mbaud capability. The multichannel IL715, IL716 and IL717 devices offer some of the industry's highest available level of integration. The IL716 and IL717 offer bi-directional capability which is ideal for ADC interfaces, PGA gain control loops and multiphase control systems.
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