The NCP1568 is a highly integrated ac−dc PWM controller
designed to implement an active clamp flyback topology. NCP1568
employs a proprietary variable frequency algorithm to enable zero
voltage switching (ZVS) of Super−Junction or GaN FETs across line,
load, and output conditions. The ZVS feature increases power density
of a power converter by increasing the operating frequency while
achieving high efficiency. The Active Clamp Flyback (ACF)
operation simplifies EMI filter design to avoid interference with other
sensitive circuits in the system. The NCP1568 features a HV startup
circuit, a strong low side driver, and a 5 V logic level driver for the
active clamp FET. The NCP1568 is suitable for a variety of
applications including ac−dc adapters, industrial, telecom, lighting,
and other applications where power density is an important
requirement.
The NCP1568 also features multimode operation and transitions
from ACF mode to Discontinuous Conduction Mode (DCM) to meet
regulatory requirements from around the world. The NCP1568 further
implements skip in standby mode, resulting in excellent standby
power. The combination of flexible control scheme and user
programmable features allow the use of NCP1568 with
Super−Junction MOSFETs (Si) and Gallium Nitride (GaN) FETs.

Features
• Topology and Control Scheme
♦ Active Clamp Flyback Topology Aids in ZVS
♦ Proprietary Multi−Mode Operation to Enhance Light Load
Efficiency
♦ Proprietary Adaptive ZVS Allows High Frequency Operation
while Reducing EMI
♦ Inbuilt Adaptive Dead−Time for Both Main and Active Clamp
FETs
♦ Peak Current−Mode Control with Inbuilt Slope Compensation
with Options
♦ Flexible Control Scheme and Programmability Allow for
Configuration with Either External Silicon or GaN FETs
• DCM and Light Load Operation
♦ Customer Programmable Optional Transition to DCM
♦ Integrated Frequency Foldback with Minimum Frequency
Clamp for Highest Performance in Standby Mode
♦ Minimum Frequency Clamp and Quiet Skip Eliminates
Audible Noise
♦ Standby Power < 30 mW
• Integrated HV and Startup Circuits
♦ 700 V Startup Circuit
♦ AC Line Brownout Detect
• Drivers
♦ 0.85 A/1.5 A Source/Sink for Low Side
♦ 65 mA/150 mA Active Clamp Driver Output

Features (Continued)
• Oscillator
♦ Programmable Frequency from
100 kHz to 1 MHz
♦ Internal Soft−Start Timer with 4
Options
• Protection
♦ Dedicated FLT Pin Compatible with
a Thermistor
♦ Adjustable Over Power Protection
(OPP)
♦ Option for Auto−Recovery and Latched
in Various Faults
♦ Internal Thermal Shutdown

Applications
• USB Power Delivery
• Notebook Adapters
• High Density Chargers
• Industrial Power Supplies