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MOS-CONTROLLED THYRISTOR POWER SWITCH ACHIEVES 2.3X CURRENT RATING OVER MOSFETs, IGBTs AND BIPOLAR DARLINGTONS IN THE SAME DIE SIZE WITH LOWER ON-STATE FORWARD VOLTAGE DROP

 MOS-CONTROLLED THYRISTOR POWER SWITCH ACHIEVES 2.3X CURRENT RATING
 OVER MOSFETs, IGBTs AND BIPOLAR DARLINGTONS IN THE SAME DIE SIZE
 WITH LOWER ON-STATE FORWARD VOLTAGE DROP
 LONG-AWAITED MCTs LET DESIGNERS CUT SIZE OF HIGH-CURRENT
 SWITCHING FUNCTIONS IN HALF
 MELBOURNE, Fla., Nov. 5 /PRNewswire/ -- The MCT (MOS-controlled thyristor), a new class of power switching device that provides a 2.3X current rating increase over MOSFETs, IGBTs and bipolar Darlingtons with a lower forward voltage drop (conduction loss, i.e. power dissipation) in the same die size as these other switches, is now available from stock. In many circuits, this means that designers can implement power switching functions with half as many devices with less than half the losses. This results in smaller, simpler and less expensive systems.
 The first available MCT, which employs integrated MOS transistors as gating devices to an SCR (silicon-controlled rectifier), is the P-type MCTV75P60E1, which can block 600V of peak off-state voltage while carrying 75 amps of continuous current at 90 degrees C case temperature with only 1.3 volt forward voltage drop.
 The MCT, which achieves this 2.3X current rating improvement in the same die size as other switches, is a cost-effective solution for high- voltage, high-current applications where minimizing conduction losses in the power switch is critical. For example, an electric car inverter evaluated by Detroit engineers and the Dept. of Energy (DOE) included prototype MCTs for power conversion which allowed a significant increase in power converter efficiency compared to using IGBTs or Darlington transistors |Ref. 1~. This power inverter converts 300 V DC to an AC voltage of 200 V RMS to drive the car's electrical motor. Other examples include switching power supplies, AC and DC motor drives, UPS systems, inverters, pulse circuits and induction heating. Such examples are referenced in Harris' MCT Users' Guide listing nearly 40 already published papers where engineers have used R&D and developmental MCTs supplied by Harris.
 Harris, (which holds basic patents for the SCR, logic-level MOS transistor and IGBT) along with many power industry experts, believes that the MCT, which combines the high-speed, low-power gate turn-on and turn-off advantages of the power MOSFET and IGBT with a thyristor's high-voltage and high-current capability, will revolutionize power switching technology.
 Compared to other semiconductor switches (IGBTs, power MOSFETs and bipolar Darlingtons), the MCT operates at a current density of about 100A/cm2, with a 1.3 V forward drop -- while the closest competitor, the IGBT, operates at a density of just 37A/cm2 with a 2.0 V or greater forward drop. This is why an MCT can achieve 2.3X current ratings over other MOS-gated power switches with the same size die. The GTO (gate turn-off SCR), which approaches the MCT in conduction efficiency, requires orders of magnitude more gate control power than the MCT.
 DESCRIPTION OF FIRST AVAILABLE MCT
 The first available MCT is the P-type MCTA75P60E1, a MOS-gated (both on and off from a single gate electrode) asymmetrical blocking SCR-type device that can block 600V of peak off-state voltage and can carry 75A of continuous cathode current at a case temperature of 90 degrees Centigrade. A key to its high efficiency as a power switch is the extremely low forward voltage drop (VTM) when in the conducting state, just 1.3V maximum at a junction temperature of 150 degrees C. The small forward drop results in low power losses in the MCT on-state.
 A P-type MCT is turned on by a gate voltage that is negative with respect to its anode. To turn the device off, an opposite polarity voltage (positive with respect to the anode) is applied to the gate.
 Like all thyristors, the MCTA75P60E1 can operate at high peak currents and withstand both large surge currents and a high rate of change of on-state current (di/dt capability). Non-repetitive peak surge current is rated at 2000 A and di/dt at 2000 A/us, but both specifications are conservative: devices can typically handle about 2 1/2 times the data sheet values. Turn-off current handling capability is another MCT advantage compared to conventional SCRs -- a peak value of 120 A at 300 volts and at a junction temperature of 150 degrees C. Unlike historical SCRs, its off-FET elements give the MCT exceptional capability to resist triggering from fast rise-time voltages applied across its main terminals (called dv/dt capability): the maximum rated value of dv/dt is 10,000 V/us. In a similar manner the MCT's on-FET elements allow the very fast turn-on that results in its 2000 A/us rated di/dt capability.
 This first available MCT is most appropriately applied to resonant circuits. With a turn-off fall time of 1.2 us, it is also appropriate for many motor control applications. Future generations will offer much higher speeds.
 PRICE AND AVAILABILITY
 Initial versions of the MCTA75P60E1 will be packaged in the plastic 5-lead MO-093 housing, a variation of the TO-218. Other package options will follow in the near future. In quantities of 100 pieces, the MCTA75P60E1 is priced at $50 each. Availability is from stock.
 HARRIS MCT PORTFOLIO PLANS
 Based on a dense, IC-like microcell structure, the MCT is a voltage- gated, high-power switching device built around an MOS gate structure that controls a classical bipolar thyristor that has both PNP and NPN transistors connected in a regenerative feedback circuit. Turn-on and turn-off are accomplished by applying negative and positive voltage, respectively, to a gate polysilicon layer that controls on and off-FET elements integrated into each micro-SCR cell.
 The introductory MCTA75P60E1 is the first of a family of P-type MCTs that will soon include 1000- and 1200 V devices by next year. A planned second generation of P-type MCTs, will switch as fast as N-channel IGBTs with less than half the conduction losses of IGBTs. The Harris MCT roadmap also includes N-type MCTs which have near ideal SOA (safe operation area) turn-off ruggedness.
 In addition, Harris plans to offer MCTs in high current modules, with and without anti-parallel diodes. A module would include several MCTs operating in parallel to handle current requirements.
 Driver ICs for MCTs are in development via Harris Semiconductor's Intelligent Power Products Group. These drivers will simplify retrofitting systems with MCTs as well as their incorporation into new systems.
 Harris Corporation's Semiconductor Sector manufactures discrete semiconductors and integrated circuits for analog and digital signal processing and power applications. It is the number one supplier to the military and aerospace market and the seventh largest U.S. merchant semiconductor manufacturer. Harris Corporation (NYSE: HRS), with worldwide sales of more than $3 billion, is focused on four major businesses: electronic systems, semiconductors, communications, and office equipment.
 |Reference 1.~ King, et al. "Numerical and Experimental Comparisons of Power Darlington, IGBT, and MCT Device as a Switch for Adjustable Speed PWM Inverter Drive Applications" Proceedings of Power Conversion and Intelligent Motion Conference, pp. 238-248 (1989).
 -0- 11/5/92
 /NOTE TO EDITOR: For U.S. publications, in addition to normal ("Bingo Card") numbers for reader response, please also use the following toll free number, 1-800-4-HARRIS, extension 7049.
 CONTACT: Linda da Costa, of Harris Semiconductor Sector, 407-724-3704/
 (HRS) CO: Harris Semiconductor Sector ST: Florida IN: CPR SU: PDT


AW-JJ -- FL010 -- 7825 11/05/92 14:59 EST
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