IXYS Introduces New Range of 2.8kV Asymmetric Thyristors

IXYS Corp. announced that its wholly owned UK subsidiary, Westcode Semiconductors Ltd., has launched two new 2.8kV Asymmetric thyristors. These thyristors are claimed to represent a new development in silicon technology, employing advanced process technology and novel device design. This advanced asymmetric structure is said to offer an improved combination of on-state voltage and turn-off time for this voltage class, which is claimed to result in better energy efficiency than symmetrical structured devices.

Available in three repetitive peak off-state voltage ratings – 2.8, 2.5 and 2kV – repetitive peak reverse voltage for all devices is limited to 10V. The larger device has a RMS current rating of 2555A; identified by part numbers A1237NC280, A1237NC250 and A1237NC200. The smaller device has RMS current rating of 1040A; identified by part numbers A0516YC280, A0516YC250 and A0516YC200. All devices are encapsulated in fully hermetic, ceramic walled packages; the A1237NC device is dimensioned 1" thick with a 1.8" diameter copper pole face, while the A0516YC device is 0.5" thick with a 1" diameter copper pole face.

Frank Wakeman, Marketing & Evaluation Manager for Westcode, commented, "The new design uses our advanced thyristor technology with an asymmetric vertical structure, optimizing the forward voltage drop against the turn-off time at the cost of the symmetrical blocking characteristic. For example, the A1237NC device has an on-state voltage of 2.1V at 2000A with a typical turn-off time of 25µs. This presents unrivalled switching speed for the current rating and voltage class. Thus, the low losses of the new device offer an excellent opportunity to design more energy efficient power control systems."

Typical applications include voltage fed induction heating power supplies operating at frequencies up to 20kHz. In resonant converters with nominal 1.2kV line voltages, where two lower voltage devices would typically be operated, a single device can be used – thereby,m according to the company, reducing cost and circuit complexity. In applications that already include an anti-parallel diode, the new thyristor can be substituted without modification to the circuit configuration to gain the benefits of its reduced on-state voltage and faster turn-off time.

Other applications include the replacement of obsolete technology including devices in thyristor traction converters for locomotive main drives. Thus, the IXYS thyristor is said to extend the life of existing equipment and reduce the impact on the environment implicit in new build replacement.