Power Electronics

Power-Management Family to Enhance Equipment Reliability and Economy

STMicroelectronics is rolling out a new family of hot-swap power-management devices that will help reduce ownership costs for important equipment such as storage devices, computers, USB accessories, enterprise systems, appliances and home electronics. The first two devices in the family provide smart, cost-effective and space-saving over-voltage and over-current protection for 5V and 12V electronics.

The STEF05 and STEF12 are electronic fuses in 3 x 3mm IC packages, which can replace larger conventional fuses or other protection devices such as transils or diodes. Unlike fuses, they do not cut the power suddenly or require replacement after actuating, thereby helping to improve equipment uptime and availability while also reducing maintenance costs. Compared to transils or diodes, the new electronic fuses enable versatile and simple programming of protection parameters.

If a fault occurs, the electronic fuse restricts the current supplied, hence protecting the connected circuitry, and ultimately turns the protected equipment off if the fault persists. It can be reset by a signal from the system or by restarting the power supply. The device provides a signal when it is intervening, allowing the system to generate a warning. If the fault persists after the reset, the fuse immediately limits the current and turns off again to protect the circuitry.

The devices also integrate circuitry that limits voltage fluctuations applied to the protected load, and programmable start-up time, allowing use in hot-swappable modules for equipment such as enterprise servers, storage or telecom systems. Hot swapping allows faulty modules to be replaced without fully powering down the system, which minimizes disruption to services.

Major features of STEF05 and STEF12:

  • Suitable for use with 5V or 12V power supplies
  • Current limit programmed by external resistor
  • Output voltage slew rate adjustable with small external capacitor
  • Output voltage clamp

The STEF05 and STEF12 are in mass production now, packaged in the 3 x 3mm DFN 10-lead package, and priced from $0.75 for orders over 1000 units. Alternative pricing may be available for higher quantities.

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