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Ideal Diode Controller Integrates 5A MOSFET to Replace Lossy Schottky Diodes

Jul 30 2008 - MILPITAS, CA
  • Linear Technology announces the LTC4358, a single high voltage ideal diode controller utilizing an internal 5A MOSFET to provide a simple, low loss replacement to Schottky diodes in high current applications. The controller and 20mΩ internal N-channel MOSFET perform the function of a low forward voltage diode. This provides a lower loss path compared to the Schottky diode that in high current applications provides higher efficiency and preserves precious board area by eliminating the need for heat sinking. The LTC4358 regulates the forward voltage drop across the internal MOSFET to ensure smooth switchover from one path to another without oscillation. A fast pull-down circuit minimizes reverse current transients in the event a power supply fails or is shorted. The LTC4358 can be viewed as a three terminal diode for general purpose applications such as reverse battery protection in automotive applications, or ORing power supplies together in applications that demand high system reliability.

    The LTC4358 single ideal diode controller is useful in applications where multiple, redundant power supplies are paralleled to provide load sharing. In N+1 redundant systems, the LTC4358 provides a convenient method to OR together an additional supply to safeguard the system in the event one of the N supplies fail. This ORing technique provides necessary isolation for live insertion and removal of converters onto the power bus and to provide isolation from the bus during a hard short. If the power source fails or is shorted, the LTC4358 ensures a fast 500ns turn-off to minimize reverse current transients.

    The LTC4358 joins a growing family of ideal diode-OR controllers, including the LTC4355 positive voltage ideal diode-OR, LTC4354 negative voltage ideal diode-OR, and the LTC4357 and LT4352 single ideal diode controllers. See table below for more details.

    Specified over the commercial and industrial temperature ranges, the LTC4358 is offered in 4mm × 3mm 14-pin DFN and 16-lead TSSOP packages. Available today, pricing begins at $2.10 each in 1,000 piece quantities.

    OR-ing Supply Range Ideal Diode Fault Monitoring Package Applications
    LTC4358 9V to 26.5V Single Internal FET No 4 × 3 DFN-14 TSSOP-16 N+1 Redundant Power Supplies Supply Hold-up
    LTC4357 9V to 80V Single No 2 × 3 DFN-6 MSOP-8 High Availability Systems Telecom Infrastructure
    LTC4352 0V to 18V Single Yes MSOP-12 3 × 3 DFN-12 Automotive Systems Optical Networks
    LTC4354 –4.5V to –80V Dual Yes 3 × 2 DFN-8 SO-8 –48V Distributed Power System AdvancedTCA Systems
    LTC4355 9V to 80V Dual Yes 4 × 3 DFN-14 SO-16 Computer Systems and Servers (RAID)

    Summary of Features: LTC4358

    • Replaces a Power Schottky Diode
    • Internal 20mΩ N-Channel MOSFET
    • 0.5us Turn-Off Time Limits Peak Fault Current
    • Operating Voltage Range: 9V to 26.5V
    • Smooth Switchover without Oscillation
    • No Reverse DC Current
    • 16-Lead TSSOP & 4mm × 3mm 14-Pin DFN Packages

    5A Ideal Diode

    LTC4358 PR Image
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