65W USB-PD adapter design uses standard superjunction or GaN FETs
The design has multiple patents pending and uses the NCP1568 active clamp flyback (ACF) controller with a corresponding high-speed, half-bridge driver – the NCP51530. This results in a 65W USB-PD compliant adapter with a 30W/in3 power density while operating at 94.5% peak efficiency.
The NCP1568 is a highly-integrated AC-DC pulse width modulation (PWM) controller that implements an ACF topology, including zero voltage switching (ZVS) for high frequency applications (up to 1 MHz) that demand high levels of power density and efficiency. A key element of the design is that the NCP1568 controller can implement ACF topology with existing superjunction (SJ) FETs or with high performance gallium nitride (GaN) FETs.
Using the high voltage start-up of the NCP1568 means the design requires few external components, reducing standby power consumption. High frequency operation reduces the size of the passive components to acheive the higher power density. Its ability to seamlessly transition to discontinuous conduction mode (DCM) further improves efficiency in light load conditions, resulting in standby power levels of less than 30mW. This also allows power supply designers to pass worldwide efficiency regulatory standards. Adaptive ZVS frequency modulation provides a variable output voltage that optimises USB-PD and Quick Charge implementation.
Housed in a small TSSOP-16 package, the NCP1568 also includes a quiet skip feature that eliminates audible noise during operation, an essential requirement for indoor power adapter applications.
The NCP51530A/B are 700V high frequency high-side and low-side drivers for directly driving two N-channel power MOSFETs in high performance power applications. A particular feature is the fast dynamic response of 30ns propagation delay for high frequency operation while the 5ns propagation delay matching ensures market leading efficiency performance.
The device provides high dv/dt immunity (up to 50 V/ns) and negative transient immunity. It is available in an SOIC-8 or DFN-10 package, with the latter offering improved creepage distances and an exposed pad. An AEC-Q100 qualified version is available in an SO-8 package for automotive applications.
“This represents a significant step forward in design for modern power adapters and battery chargers,” said Ryan Zahn, Director of Marketing and Applications for the AC-DC Business Group at ON Semiconductor. “Advanced features and flexible operation in the NCP1568 ACF controller deliver excellent efficiency, while using SJ FETs, and requiring few external components, thereby enabling high density designs to be realised for USB PD. The NCP51530 drivers are a high-speed, high-performance robust power solution that includes the option of AEC Q-100 qualification for automotive applications.”
The NCP1568 and the NCP51530 are sampling now, and will be in full production in Q2, 2018.