Surge stopper provides overvoltage protection

A new surge suppressor provides overvoltage and overcurrent protection to high-availability electronic systems. The LT4363 overvoltage protection controller from Linear Technology Corp. features a robust, adaptable, and space-efficient design with control of an N-channel MOSFET. The device extends overvoltage protection capabilities beyond 100 V without sacrificing overcurrent protection. Supply voltages surge whenever currents flowing through long inductive-power buses change abruptly. With the LT4363, only the controller and the MOSFET suffer the high-voltage surge, so that downstream components can afford lower voltage ratings. The controller also reacts quickly to overcurrent and short-circuit faults at the load, limiting the current to a safe value set by a sense resistor.
A simple clamp on the controller supply extends protection beyond the native 100 V and can survive reversed battery connections to -60 V. During voltage surges, the output is regulated to a voltage set by a resistive divider, allowing the load to operate safely and smoothly through transient events. Overvoltage and undervoltage comparator inputs ensure that the LT4363 remains off outside of a user-defined voltage range. To limit the thermal stress on the power MOSFET, the device uses a V_DS–accelerated fault timer. If the fault persists, a warning is issued before the MOSFET is shut off. By limiting the MOSFET gate slew-rate with a resistive-capacitive (RC) network, the controller can be adapted for inrush control in hot swap applications. In the shutdown state, the controller uses only 7 µA of supply current, preserving battery life. A built-in thermal shutdown occurs around 150°C.

Key features:

• Withstands surges over 100 V with V_cc clamp
• Operating voltage range: 4 V to 80 V
• Adjustable output clamp voltage
• Overcurrent limit less than 5 µs
• Reverse input protection to –60 V
• Adjustable UV/OV comparator thresholds
• 7 µA shutdown current
• Shutdown pin withstands –60 V to 100 V
• Adjustable fault timer
• Controls N-channel MOSFET
• Less than 1% retry duty cycle during faults (LT4363-2)

The LT4363 is available in two options: the LT4363-1 latches off after a fault, whereas the LT4363-2 will retry after a long cool-down period. Specified over the full commercial and industrial temperature ranges, the device is offered in 12-pin DFN (4 mm x 3 mm) and MSOP packages, and a 16-pin SO package with enhanced high-voltage pin spacing. Pricing begins at $2.48 each for 1,000-piece quantities, and the device is now available in production quantities. For more information, visit www.linear.com/product/LT4363.