On Semi公司的NCP1568是AC/DC转换器高度集成的有源箝位PWM控制器,采用有所有权的可变频率算法来实现超级结或GaN FET跨越线路和负载条件下的零电压开关(ZVS),从而增加功率密度,达到高效率.器件具有高压起动电路,强大的低边驱动器和用于有源箝位FET的5V逻辑电平驱动器,主要用在AC/DC适配器,工业,通信,照明和其它功率密度是主要考虑的应用.本文介绍了NCP1568主要特性,框图,应用电路和通用输入60W参考设计主要特性,电路图,材料清单和PCB设计图.
The NCP1568 is a highly integrated AC−DC PWM controllerdesigned to implement an active clamp flyback topology. NCP1568employs a proprietary variable frequency algorithm to enable zerovoltage switching (ZVS) of Super−Junction or GaN FETs across lineand load conditions. The ZVS feature increases power density of apower converter by increasing the operating frequency whileachieving high efficiency. The Active Clamp Flyback (ACF)operation simplifies EMI filter design to avoid interference with othersensitive circuits in the system. The NCP1568 features a HV startupcircuit, a strong low side driver, and a 5 V logic level driver for theactive clamp FET. The NCP1568 is suitable for a variety ofapplications including Ac−Dc adapters, industrial, telecom, lighting,and other applications where power density is an importantrequirement.
The NCP1568 also features multimode operation and transitionsfrom ACF mode to Discontinuous Conduction Mode (DCM) to meetregulatory requirements from around the world. The NCP1568 furtherimplements quiet skip in standby mode, resulting in excellent standbypower while eliminating acoustic noise. The combination of flexiblecontrol scheme and user programmable features allow the use ofNCP1568 with Super−Junction MOSFETs (Si) and Gallium Nitride(GaN) FETs.
Topology and Control Scheme
♦Active Clamp Flyback Topology Aids in ZVS
♦Proprietary Multi−Mode Operation to EnhanceLight Load Efficiency
♦Proprietary Adaptive ZVS Allows High FrequencyOperation while Reducing EMI
♦Inbuilt Adaptive Dead−Time for Both Main andActive Clamp FETs
♦Peak Current−Mode Control with Inbuilt SlopeCompensation with Options
♦Flexible Control Scheme and ProgrammabilityAllow for Configuration with Either External Siliconor GaN FETs
DCM and Light Load Operation
♦Customer Programmable Optional Transition toDCM
♦Integrated Frequency Foldback with Minimum
Frequency Clamp for Highest Performance inStandby Mode
♦Minimum Frequency Clamp and Quiet SkipEliminates Audible Noise
♦Standby Power < 30 mW
Integrated HV and Startup Circuits
♦700 V Startup Circuit
♦AC Line Brownout Detect and Integrated X2Capacitor Discharge
♦1.25 A/2.5 A Source/Sink for Low Side
♦100 mA/200 mA Active Clamp Driver Output
♦Programmable Frequency from 100 kHz to 1 MHz
♦Internal Soft−Start Timer with 4 Options
♦Dedicated FLT Pin Compatible with a Thermistor
♦Adjustable Over Power Protection (OPP)
♦Option for Auto−Recovery and Latched in Various
♦Internal Thermal Shutdown
USB Power Delivery
High Density Chargers
Industrial Power Supplies
This design notes describes a 60 W universal input 5 V, 9 V, 12 V, 15 V and 20 V output evaluation board for laptop adapters. This featured power supply is an active-clamp flyback topology utilizing ON Semiconductor’s NCP1568 PWM ontroller, NCP51530 HB Driver, NCP4305 SR Controller and FDMS86202 SR FET. This design note provides complete circuit schematic, PCB, BOM and transformer information of the evaluation board. It also provide efficiency, transient response, output ripple and thermal data of the evaluation board.
This design utilized NCP1568 and NCP51530 for the active clamp flyback topology. Active clamp flyback topology effectively recycles the leakage energy. Another feature of this topology is the ZVS operation of the power MOSFETS. Because of no leakage losses and ZVS operation, this topology is suited for high frequency operation which results in size reduction of the transformer. Hence Active clamp flyback topology is well suited for high power density sub 100 W power supplies. A ZVS fixed switching frequency power converter also simplifies EMI design and can be easily designed to avoid interference with other sensitive circuits in the system.
NCP1568 is a highly integrated Ac-Dc PWM controller designed to implement an active clamp flyback topology. It features adaptive frequency scheme which optimizes frequency of operation and hence the efficiency over all load and input voltages. The NCP1568 features a HV startup circuit along. It also has integrated X2 discharge circuit.
NCP51530 is a 700 V high side and low side driver with 2 A current drive capability for AC-DC power supplies and inverters. NCP51530 offers best in class propagation delay, low quiescent current and low switching current at high frequencies of operation. This device is tailored for highly efficient power supplies operating at high frequencies.
NCP4305 is high performance driver tailored to control a synchronous rectification MOSFET in switch mode power supplies.
NCP4328 is a secondary side SMPS controller with wide operating voltage range, designed for use in constant current and/or constant current regulation.
• Universal AC input operation (90 -265 Vac)
• High full load and average efficiency
• Low standby power
• Very low ripple and noise
• High frequency operation up to 450 kHz
• Inherent SCP and OCP protection
• Thermal and OVP protection
• Adaptive frequency operation based on AC input and output load conditions
• Adaptive ZVS operation.
• Smaller EMI components.
• Multiple probe points for evaluation
• Smooth startup operation