Faster thyristor gives power designers more options

August 04, 2016 // By Nick Flaherty
The 20 μs turn-off time of a 16 kV pressure contact distributed gate thyristor developed by IXYS UK Westcode (Chippenham, UK) is giving high power system developers more design options.

The N1955MC16 developed by the UK subsidiary of IXYS has a turn-off time of 20 μs and a current rating of 1,955 A. The symmetrical blocking with forward and reverse voltage equal to 1,600 V makes it suitable for both voltage and current fed applications such as induction heating and resonsant power supplies. The increase in current rating can be traded in adapting the turn-off characteristic to give faster turn-off even than the standard offering of 20 μs or tailoring the reverse recovery for series operation.

The device offers higher current, while retaining the same turn-off time, when comparted to other parts in the same footprint package size. The improved design has an average current rating of 1,955 A at a heat sink temperature of 55 ºC, a 35% increase over older IXYS designs. The improvement in performance is achieved by maximising the die size and improved distributed gate geometry. The 56 mm silicon dice are bonded to metal discs and encapsulated in fully hermetic 50 mm electrode contact diameter ceramic packages, with an industry standard overall diameter of 74 mm.

“Providing the correct thermal conditions are observed, with a repetitive di/dt rating of 1,000 A/s, the device can be used in applications with repetitive frequencies up to 25 kHz,” said Frank Wakeman, IXYS UK’s Marketing and Technical Support Manager.