Protection of sensitive electronic components from overvoltage exceeding 100V

January 17, 2012 – Linear Technology Korea (CEO Hong Sa-kwak) announced the launch of an overvoltage protection controller (product name: LT4363) that provides overvoltage and overcurrent protection for high-availability electronic systems. Supply voltage rises whenever the current flow through a long inductive power bus changes abruptly. Automotive batteries can experience situations where the voltage spikes for a significant number of milliseconds, such as a load dump. To address this, conventional protection circuits rely on large inductors, capacitors, fuses, and transient voltage suppressors; however, the LT4363 features a robust, flexible, and space-efficient design that allows for simpler control of N-channels. Only the controller and MOSFETs are capable of withstanding high-voltage surges, while downstream components can utilize low-voltage ratings, thereby reducing costs.
The LT4363 controller is designed based on Linear's popular first-generation LT4356 device and features extended overvoltage protection above 100V without sacrificing overcurrent protection. The LT4363 responds quickly to overcurrent and short-circuit faults in the load, limiting the current to a stable level through a sense resistor.
Offering a maximum rated voltage of 100V and an operating range of as low as 4V (during cold crank), the LT4363 provides an ideal solution for power supplies prone to various issues. A simple clamp on the controller supply provides protection against voltages exceeding 100V. This product can also withstand reverse battery connections down to -60V. During a voltage surge, the output is regulated to a voltage set by a resistor divider, allowing the load to operate safely and smoothly through transient events.
Overvoltage and undervoltage comparator inputs ensure that the LT4363 does not exceed the user-defined voltage range. To limit thermal stress on power MOSFETs, the LT4363 utilizes a VDS accelerated fault timer. If the fault persists, a warning is continuously issued before the MOSFET is turned off. By limiting the MOSFET gate slew rate with a resistive-capacitive (RC) network, this controller can be tailored for surge current control in Hot Swap™ applications. Battery life is saved because the LT4363 uses only 7µA of supply current in the shutdown state. Built-in thermal shutdown occurs at approximately 150°C.
The LT4363 is available in two options. The LT4363-1 latches off after a fault, while the LT4363-2 restarts after a long cool-down period. Operating over the full commercial and industrial temperature range, the LT4363 is available in 12-pin DFN (4mm x 3mm) and MSOP packages, as well as a 16-pin SO package with enhanced high-voltage pin spacing. Pricing starts at $2.48 per unit for 1,000 units, and production-ready products are available immediately. For more information, please visit www.linear.com/product/LT4363 .

Photo Caption: Suppressing high-voltage surges with overvoltage and overcurrent protection IC

Product Features: LT4363
• Can withstand surges of over 100V with Vcc clamp
• Wide operating voltage range: 4V ~ 80V
• Adjustable output clamp voltage
• Fast overcurrent limiting: Less than 5μs
• Provides reverse input protection down to -60V
• Adjustable UV/OV comparator threshold
• Low 7μA shutdown current
• Shutdown pin can withstand –60V to 100V
• Adjustable fault timer
• N-channel MOSFET control
• Restart duty cycle of less than 1% in case of failure (LT4363-2)
• 12-pin MSOP (4mm x 3mm) DFN and 16-pin SO packages