Magnetoresistive 2-channel isolators with very high CMTI

To control SiC FET circuit breakers – e.g. in on-board and off-board chargers – a galvanic isolation between gate drivers and micro-controllers with a sufficiently high pulse strength CMTI (Common Mode Transient Immunity) and high isolation is required. The high switching frequencies of SiC MOSFETs can generate very steep voltage peaks of up to 150 V/ns. 

The magnetoresistive, digital, 2-channel isolators of the NVE IL7xx series were specially optimised for this type of SiC application. They don’t just offer a CMTI > 150 V/ns, but also an isolation of 6 kV or more. The symmetrical design of the magnet coupling ensures a maximum pulse width distortion of 3 ns. Together with a gate delay of under 10 ns, this enables controlled timing over the entire signal chain. 

The isolators of the IL7xx series are also suitable for galvanic isolation in other applications, e.g. in sensors. They correspond to the lifetime model (EOL model) according to VDE0884-11 and are already being tested by NVE in accordance with the current specifications of the IEC 60747-17:2020 standard. The new procedure prescribes a merging of the test intervals for isolation and partial discharge (PD) without a pause. Products with marginal properties are thus sorted out in advance. Ageing effects, as in the case of optocouplers, do not occur here. The service life is effectively only determined by the isolation technology and can easily reach 30 years or more. For the IL721VE, the manufacturer even specifies a theoretical service life of 44,000 years in the data sheet!

The isolators from NVE can be found, along with other state-of-the-art components for the development of charger technology in the field of e-mobility, in the range offered by Angst+Pfister Sensors and Power (formerly Pewatron). This also includes the new BeFAST evaluation board – a versatile development tool for determining the relevant circuit properties in interaction with all essential components such as SiC FET, DC-DC converters, isolators, thermistors, etc.

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