Catalog
Synchronous Rectifier Controller
Key Features
• Self−Contained Control of Synchronous Rectifier in CCM, DCM and QR for Flyback or LLC Applications
• Precise True Secondary Zero Current Detection
• Rugged Current Sense Pin (up to 150 V)
• Adjustable Minimum ON−Time
• Adjustable Minimum OFF-Time with Ringing Detection
• Adjustable Maximum ON−Time for CCM Controlling of Primary QR Controller
• Operating Voltage Range up to VCC = 35 V
• 8 A / 4 A Peak Current Sink / Source Drive Capability
• GaN Transistor Driving Capability (options A and C)
• Low Startup Current Consumption
• Maximum Operation Frequency up to 1 MHz
• Improved Robust Self Synchronization Capability
• SOIC-8 and DFN−8 (4x4) and WDFN8 (2x2) Packages
• These are Pb−Free Devices
Description
AI
The NCP4308 is a synchronous rectifier controller for switch modepower supplies. The controller enables high efficiency designs forflyback, quasi resonant flyback and LLC topologies.Externally adjustable minimum off−time and on−time blankingperiods provides flexibility to drive various MOSFET package typesand PCB layout. A reliable and noise less operation of the SR system isinsured due to the Self Synchronization feature. The NCP4308 alsoutilizes Kelvin connection of the driver to the MOSFET to achieve highefficiency operation at full load.The precise turn−off threshold, extremely low turn−off delay timeand high sink current capability of the driver allow the maximumsynchronous rectification MOSFET conduction time. The highaccuracy driver and 5 V gate clamp make it ideally suited for directlydriving GaN devices.To provide more flexibility in PCB layout there are two versions of this product.NCP4308 does NOT have LLD functionNCP43080 has LLD function
