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