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 device 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. It 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 and an adjustable fault timer ensures safe shutdown if the fault persists.
The device is suitable for harsh industrial, automotive and avionic applications where systems must continue operating reliably through severe overvoltage events. 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.
The LTC4366 is available in two options; the LTC4366-1 latches off after a fault, while the LTC4366-2 will retry after a 9-second cool down period. Devices are specified over the full commercial, industrial and automotive temperature ranges.