Floating surge stopper provides unlimited overvoltage protection

The LTC4366 floating surge stopper utilises an adjustable floating topology which Linear says enables very high voltage operation independent of the voltage rating of device's internal circuitry. Two internal shunt regulators, coupled with the external voltage dropping resistors generate the LTC4366's internal supply rails and the maximum operating voltage is set by the breakdown of the external resistors and mosfets. According to Linear, it 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 device has been designed to monitor the voltage at its output and react quickly to input supply overvoltage by controlling the gate of an N-channel mosfet. It regulated 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 is said to ensure safe shutdown if the fault persists. The LTC4366 is suitable for harsh industrial, automotive and avionic applications where systems need to continue operating reliably through severe overvoltage events. Linear says that unlike traditional protection circuitry, which relies on bulky inductors, capacitors, fuses and transient voltage suppressors to clamp the transient, the LTC4366 protects by series regulating the transient. High voltage applications include protecting from motor transients, coupled overvoltage, incorrect input supplies or power supply failures. The device is packaged in an 8lead TSOT-23 and 3mm x 2mm DFN packages. During operation, the entire circuit consumes a few milliamperes and it may be shut down to less than 20µA.