Secondary-Side Synchronous Rectification Driver for High-Efficiency SMPS

The NCP4306 from ON Semiconductor is high-performance driver tailored to control a synchronous rectification MOSFET in switch mode power supplies (SMPS). Due to its high performance drivers and versatility, it can be used in various topologies such as DCM or CCM flyback, quasi resonant flyback, forward and half bridge resonant LLC.

The combination of externally or fixed adjustable minimum off-time and on-time blanking periods helps to fight the ringing induced by the PCB layout and other parasitic elements. A reliable and noise less operation of the SR system is insured due to the Self Synchronization feature.

The NCP4306 also utilizes Kelvin connection of the driver to the MOSFET to achieve high efficiency operation at full load and utilizes a light load detection architecture to achieve high efficiency at light load.

The precise turn−off threshold, extremely low turn−off delay time and high sink current capability of the driver allow the maximum synchronous rectification MOSFET conduction time and enables maximum SMPS efficiency. The high accuracy driver and 5 V gate clamp enables the use of GaN MOSFETs.

Applications are expected to include:

  • Notebook Adapters
  • Server Power Supplies aux power stage
  • ATX & All-in-one Power Supplies
  • High Density USB Adapters

Features and associated benefits include:

  • Precise True Secondary Zero Current Detection
    • Allows for proper timing of SR MOSFET turn on and turn off
  • Typically 13 ns Turn off Delay from Current Sense Input to Driver
    • Maximizes conduction time of the MOSFET to increase efficiency
  • Zero Current Detection Pin Capability up to 200 V
    • Allows direct connection of CS input to MOSFET drain in flyback applications
  • Optional Ultrafast (10.5ns) Trigger Input
    • Improves performance for applications working in deep CCM
  • Disable Input
    • Enters the IC into a low consumption standby mode
  • Adjustable Minimum ON Time and Minimum OFF Time
    • Prevents accidental MOSFET turn on or turn off due to ringing
  • dV/dt detection
    • Enhanced Operation for USB-PD Applications
  • 7A Sink, 2A Source Drive capability
    • Fast turn off of MOSFET for optimized conduction period
  • Automatic Light Load Disable Mode
    • Increased stability coming in and out of Light Load
  • 5V UVLO and Operation Voltage range up to 35V
    • Wide output operating voltages

Typical Application Example – LLC Converter with optional LLD and Trigger Utilization (click on schematic to enlarge)

Typical Application Example – DCM, CCM or QR Flyback Converter with optional LLD and disabled TRIG (click on schematic to enlarge)

Typical Application Example – DCM, CCM or QR Flyback Converter with NCP4306 in TSOP (click on schematic to enlarge)

Typical Application Example – Primary Side Flyback Converter and NCP4306 in TSOP (click on schematic to enlarge)


ON Semiconductor
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