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Overvoltage protection regulator suits car, industrial apps

Posted: 11 Jul 2007 ?? ?Print Version ?Bookmark and Share

Keywords:overvoltage protection regulator? DC/DC regulators? industrial apps?

Linear Technology Corp. has introduced an overvoltage protection regulator with overcurrent protection and inrush current limiting for high-availability systems. LT4356 targets applications where electronic systems must deal with high-voltage surges of short duration such as load dump in automobiles. Applications include automotive, industrial and avionics as well as positive high-voltage distributed power Hot Swap systems.

The LT4356 device offers a wide input operating range of 4-80V, which enables continuous operation during cold crank conditions where the battery voltage can be as low as 4V, said Linear. With its high input voltage rating, LT4356 can handle transient voltages of 100V and higher and provides reverse input protection to -30V without damage to itself or the load.

LT4356 replaces bulky protection circuitry with a simple IC and FET solution, said Linear. It provides a well-regulated output during an overvoltage transient, allowing continued operation through the event. Front-end protection permits the use of lower cost DC/DC regulators downstream. During an overvoltage event, LT4356 regulates the output to a user-defined voltage by controlling the gate of an external n-channel MOSFET. Inrush current limiting is achieved by controlling the voltage slew rate of the gate.

LT4356 monitors voltage drop across a current sense resistor at the input of the circuit to protect against overcurrent faults. For either an overvoltage or overcurrent fault condition, an integrated fault timer ensures safe shutdown of the MOSFET if the fault persists.

An auxiliary amplifier is provided for additional design flexibility. It may be used as a voltage detection comparator or a low drop out (LDO) linear regulator controller. LT4356 is available in two options defined by the function of the shutdown pin. For the LT4356-1, shutdown of the IC reduces the quiescent current to 5?A. For the LT4356-2, the auxiliary amplifier and internal reference remain active to ensure a keep-alive supply voltage for vital functions while the main system is shutdown. Quiescent current is reduced to 50?A during shutdown.

Specified over the full commercial, industrial and automotive temperature ranges (-40C to 125C), LT4356 is offered in 12-pin DFN (4-by-3mm) and 10-pin MSOP packages. Evaluation kits are available from the factory.

Production quantities are available now. Pricing starts at $1.98 each for 1,000-piece quantities.

- Gina Roos

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