Author:
Reported by Cliff Keys, Editorial Director, PSD
Date
01/10/2012
PDF
.jpg)
I had the pleasure of talking with Bob Reay, Vice President, Mixed Signal Products and Alison Steer, Product Marketing Manager, Mixed Signal Products for Linear Technology about a revolutionary new product from this vastly innovative company. This product will certainly be another ‘superstar' in the industry. In automotive, industrial and avionic applications, high voltage power supply spikes with durations ranging from a few microseconds to hundreds of milliseconds are commonly encountered. The electronics within these systems must not only survive transient voltage spikes, but in many cases also operate reliably throughout the event. In systems where power is distributed over long wires severe transients are generated by load steps (abrupt changes in load current). Negative load steps happen when load current drops from a high value to a low value. Negative changes in current (dI/dt) cause the wire's parasitic inductance to generate a positive-going high voltage spike which can cause damage to neighboring devices powered from the same wire. High values of dI/dt are produced by fast load switching, such as caused by relays, switch contacts and solid state load switching. Corroded connections between a power source and load can lead to an abrupt interruption of current flow, and a high value of dI/dt. The best example of this condition is automotive load dump; where there is a sudden break in the connection to the battery caused by vibration and corroded terminals.
.jpg)
Linear's LTC4366, an overvoltage protection controller for electronic systems operates from 9V to greater than 500V, the LTC4366 floating surge stopper utilizes an adjustable floating topology to enable very high voltage operation independent of the voltage rating of the LTC4366's internal circuitry. Two internal shunt regulators coupled with the external voltage-dropping resistors generate the LTC4366's internal supply rails. The maximum operating voltage is set by the breakdown of the external resistors and MOSFETS. The LTC4366 is the first product of its kind to protect, for example, a 12V circuit from a 500V transient without the need for additional protection components. The LTC4366 monitors the voltage at its output and reacts quickly to input supply overvoltage by controlling the gate of an N-channel MOSFET. The LTC4366 regulates the output to a user-defined voltage during an overvoltage transient allowing the load to remain operational while the overvoltage is dropped across a MOSFET. An adjustable fault timer ensures safe shutdown if the fault persists. The LTC4366 is ideal for harsh industrial, automotive and avionic applications where systems must continue operating reliably through severe overvoltage events.
.jpg)
High voltage applications include protecting from motor transients, coupled overvoltage, incorrect input supplies or power supply failures. While traditional protection circuitry relies on bulky inductors, capacitors, fuses and transient voltage suppressors to clamp the transient, the LTC4366 protects by series regulating the transient. It is packaged in a tiny 8-lead TSOT-23 and 3mm x 2mm DFN packages. During operation, the entire circuit consumes only a few milliamperes, and the device may be shut down to less than 20μA. Summary of Features: LTC4366
