Spotlight on Circuit Protection

Aug. 1, 2007
Power System Simulator Opal-RT's eMEGAsim is a distributed, parallel computing system for real-time simulation of electromagnetic transients in power systems.

Power System Simulator

Opal-RT's eMEGAsim is a distributed, parallel computing system for real-time simulation of electromagnetic transients in power systems. The system combines RT-LAB and FPGA technology to obtain simulation time steps below 250 ns. The system is designed for real-time simulation, integration and hardware-in-the-loop testing of protection devices and power-electronic controllers. It also can be adapted for real-time simulation of complete power systems installed in vehicles or large power-grid systems.
Montreal, Canada

Output-Current Monitor

The ZXCT1050 current monitor from Zetex Semiconductors ensures accurate current measurement, even if the load is short circuited, while improving overall power efficiency. Able to operate on both high and low sides of the load, the monitor supports dynamic output-current limitation circuits in a broad range of applications with a 50-µA quiescent current. The common-mode range of the device spans from ground to within 2 V of the supply voltage. Voltage is translated across an external sense resistor into an accurate, proportional output current. The monitor is in the SOT23-5 package and operates from -40°C to +125°C. The ZXCT1050 current monitor is $0.63 each in 1000-piece quantities.
Zetex Semiconductors
Manchester, England

Hot-Swap Protection IC

Allegro MicroSystems' ACS760, designed for 12-V applications, combines Hall-effect current-sensing technology with hot-swap-control circuitry. No external sense resistor is required. The device incorporates an external high-side FET gate drive and produces an analog output voltage (factory trimmed for gain and offset) that is proportional to the applied current. Three levels of fault protection are integrated within the ACS760: 240-VA power fault protection with user-programmable delay; user-programmable overcurrent fault threshold with programmable delay; and short-circuit protection, which disables the gate in less then 2 µs. The ACS760 is supplied in a 24-lead QSOP package and priced at $4 each in quantities of 1000.
Allegro MicroSystems
Worcester, Mass.

Space-Grade Fuse

Schurter's MGA-S SMD fuse meets the standard of ESA/SCC Generic Specification 4008 for space applications. The device also meets the requirements of the space industry, including additional pre-arcing times, consistency of overcurrent disconnects at rated voltage regardless of vacuum conditions, stable derating curves at higher ambient temperatures and durability against mechanical vibration and shock. Every component is extensively tested by means of a burn-in procedure to validate correct functioning. The dimensions of the MGA-S are the 1206 footprint. The MGA-S is tested according to Mil-Std 202, Method 108A, 103B, 106E, 107D, 211A and 215A.
Schurter Inc.
Santa Rosa, Calif.

Zener Voltage Clamp

Tyco Electronics has extended its line of PolyZen polymer-enhanced precision zener diode micro-assemblies to offer 48-V overvoltage suppression. The ZEN132V075A48LS offers a 13.2-V zener voltage clamp, with the ability to lock out continuous overvoltage sources of up to 48 Vdc. The device is designed to help protect sensitive portable electronics from damage caused by inductive voltage spikes, voltage transients, incorrect power supplies and reverse bias. Pricing is $0.27 each in quantities of 100,000 units per year.
Tyco Electronics
Menlo Park, Calif.

Fuse Modules

Ferraz Shawmut's 600-V ULTRASAFE Fuse Modules are suited for use with 45-mm-wide IEC contactors. These 3-pole fuse modules offer finger-safe fuse changes. The fuse modules can replace circuit breakers in motor starters for superior short-circuit current ratings, and each module includes an auxiliary contact option for increased user protection. The auxiliary is wired to an adjacent contactor, and the contactor drops the load upon opening the fuse extractor handle. Each module also features compact bus bars for line-side terminations.
Ferraz Shawmut
Newburyport, Mass.

Overvoltage Protection Regulator

Linear Technology's LT4356 is an overvoltage protection regulator, with overcurrent protection and inrush current limiting for high-availability systems. In applications such as load dump in automobiles, the LT4356 provides front-end protection for downstream components. The input operating range of 4 V to 80 V enables continuous operation during cold-crank conditions. The device also can withstand transients of -30 V and greater than 100 V. Specified over the full commercial, industrial and automotive temperature ranges, the LT4356 is offered in (4-mm × 3-mm) 12-pin DFN and 10-pin MSOP packages. Pricing begins at $1.98 each for 1000-piece quantities.
Linear Technology
Milpitas, Calif.

Overvoltage-Protection Controllers

From Maxim Integrated Products, the MAX4943 through MAX4946/MAX4949 are overvoltage-protection controllers with an integrated nFET. These devices provide overvoltage protection up to +28 V with overvoltage trip levels ranging from 4.56 V to 8.9 V and undervoltage trip levels ranging from 2.45 V to 4.15 V. Integrating the nFET switch into the devices' 2-mm × 2-mm microDFN package reduces the overall external system-component count and board space. The controller also features a 1.7-A (typ.) current-limiting function to protect against short circuits. Prices start at $1.14 each in lots of 1000.
Maxim Integrated Products
Sunnyvale, Calif.

Sponsored Recommendations


To join the conversation, and become an exclusive member of Electronic Design, create an account today!