Linear's high-power negative supply ideal diode-OR controller withstands ±300V transients



LTC4371 rugged ideal diode-OR controller

Linear Technology introduced the LTC4371, a rugged ideal diode-OR controller for dual feed high power telecom and datacom boards. The LTC4371 provides seamless handoff between redundant power supplies, replacing power Schottky diodes and associated heat sinks with N-channel MOSFETs, significantly reducing power loss, voltage drop and solution size.

The controller is designed to withstand ±300V or higher voltage transients experienced during lightning induced surges, load switching or supply short-circuit, for the most rugged diode-OR solution available. A built-in shunt-regulated supply with low 350µA quiescent current and high impedance drain pins enables large value external resistors to safely limit device current during such high voltage transients. External transient voltage suppressors are eliminated, saving cost and board area.

The LTC4371 servos a low 15mV forward voltage drop across the ideal diode MOSFETs to minimize power dissipation in high current applications. The linear servo technique blocks DC reverse current while ensuring smooth current transfer during supply switchover. During an input supply short-circuit, transient reverse current is minimized by a powerful 2A gate turn-off current. A strong 5mA gate pull-up current ensures rapid turn-on of the MOSFET, enabling AC rectification applications.

The large gate currents provide plenty of drive when multiple MOSFETs are paralleled in high current 50A and 100A applications. Operating voltage range extends into the hundreds of volts due to the internal shunt regulator, while a 4.5V minimum supply accommodates low voltage -5V and -12V ORing applications. Open-circuit failure of the MOSFET or a series fuse is detected and signaled by a fault status output.

Specified over the 0°C to 70°C commercial and -40°C to 85°C industrial temperature ranges, the LTC4371 is offered in 10-pin MSOP and 3mm x 3mm DFN plastic packages. 1,000-piece pricing starts at $2.50 each. Device samples and evaluation circuit boards are available online or from your local Linear Technology sales office. For more information, visit .

Summary of Features
Low Loss ORing of Two Negative Voltage Supplies
Replaces Power Schottky Diodes & Associated Heat Sinks
Withstands > ±300V Transients
Low 15mV Ideal Diode Drop for Reduced Dissipation
Low 350µA Quiescent Current
100V Rated High Impedance Drain Pins
Internal Shunt Clamp for High Voltage Applications
-4.5V Minimum Operation
Fast < 220ns Reverse Current Turn-Off
5mA Gate Pull-Up Current for 60Hz Applications
Open MOSFET & Open Fuse Detection
10-Pin MSOP & 3mm x 3mm DFN Packages 


Linear Technology