Semiconductor Fuses

A power semiconductor device is a high power electronic device that is used as a switch for control and conversion in electric power. The use of power semiconductor devices in modern power electronics is driven by the need for better power efficiency, with the ultimate goal of achieving as close to 100% power efficiency as possible. In addition to power efficiency, there is a need to make the device as small as possible, which is a driving factor as to why power semiconductors have replaced older electro-mechanical components.

Typical equipment using power semiconductor devices includes inverters, rectifiers, electric vehicle battery management systems, locomotive traction drives, industrial motor drives, factory automation systems, air conditioners, computers, telecom devices, battery chargers, and many more. To protect these very sensitive power semiconductor devices from an overcurrent fault, an extremely fast acting and low energy let-through circuit protection device is needed. The only device available in the world to protect these sensitive devices are semiconductor fuses. .

Understanding the protection requirements and selecting the right semiconductor fuse for your application can be an overwhelming, time-consuming process even for a seasoned power electronics design engineer. An important part of developing quality overcurrent protection is understanding system needs and overcurrent protective device fundamentals.

  • Overload Fault Condition: Defined as an overcurrent that is confined to the normal current path, which if allowed to persist in the circuit, will cause damage to equipment and/or any connected wiring. Overcurrent protective devices must disconnect circuits and equipment experiencing continuous overloads before any overheating occurs.
  • Short-Circuit Fault Condition: An overcurrent that flows outside its normal current path in the circuit is a short-circuit fault condition. A short-circuit fault is most commonly caused by an insulation breakdown or a faulty connection. When a short-circuit fault occurs, the current bypasses the normal load and takes a shorter path, hence the term short-circuit.

Performance capabilities of semiconductor fuses are determined in the form of various characteristic curves where two or more electrical performances are compared and represented graphically. Typical semiconductor fuse characteristic curves include:

  • Time Current Curve
  • Watt Loss Performance Curve
  • Temperature Derating Curve
  • Peak Let-through Current Curve
  • Arc Voltage Curve
  • I2t Curve