Designed based on ST-ONE digital controller and MasterGaN2

The STDES-65ACFADP is a 65W active clamp flyback adapter reference design for USB Type-C that shows high efficiency performance across the entire operating load range and universal power input voltage range. The reference design paves the way for compact solutions using planar transformer technology and provides a peak efficiency of 93.7% at full load. It also meets CoC Level 2 and DoE Level 6 average efficiency requirements. The soft switching topology helps reduce switching losses while the low quiescent current consumption makes it the best no-load consumption in its class. The DEMO board mainly uses the ST-ONE digital controller to implement the proprietary ZVS active clamp flyback with low RMS current, thus achieving high performance. The controller promises to improve the efficiency of a wide range of AC-DC adapters, including laptops and smartphone chargers, fully compliant with USB-PD 3.1. Secondary losses are minimized using the synchronous rectification digital control embedded in the ST-ONE. On the primary side, due to the performance of MasterGaN2, switching and conduction losses are reduced and reverse recovery losses are eliminated, thus ensuring higher efficiency. Highly integrated MasterGaN IC, so no need to consider the complexity of GaN driving, you can enjoy the benefits of GaN technology, enhance the stability of the application and simplify the PCB layout.

The new ST-ONE controller drives the ST MasterGaN power output module based on advanced gallium nitride (GaN) semiconductor technology. Gallium nitride wafers can significantly save energy and reduce the size of the device. Designers of USB Type-C™ Power Delivery compliant adapters and wall chargers can benefit from ST-ONE+MasterGaN, the highest power density solution for USB-PD chargers.

Introduction of MasterGaN 2:

The design of MasterGaN demonstrates how the new highly integrated devices can improve power density and energy efficiency, simplify product design, and shorten the time to market for marketed products. Taking advantage of the high energy efficiency of GaN power transistors, the reference design adopts a heat sink-free design on the primary side. In addition, GaN transistors have excellent switching performance and operate at higher frequencies than ordinary silicon-based MOSFET solutions, so smaller electromagnetic components and capacitors can be used to achieve higher power density and lower bill of materials costs. ST's MasterGaN integrates an STDRIVE half-bridge gate driver and two 650V enhancement-mode GaN transistors. Currently, the MasterGaN series has symmetrical and asymmetrical configurations of MasterGaN1/2/3/4/5, of which MasterGaN1/4/5 is a symmetrical configuration that integrates two GaNs with the same internal resistance of the upper and lower tubes, using a 9mm x 9mm thin GQFN package, the internal circuit of the package is rated for up to 650V, and the maximum creepage distance between the high and low voltage pads exceeds 2mm.

MASTERGAN2 is an advanced packaged power system that integrates a gate driver and two enhancement-mode GaN transistors with an asymmetrical half-bridge structure. The integrated power GaN has a 650 V drain-source blocking voltage and RDS(ON) of 150 mΩ and 225 mΩ for the low and high sides respectively, while the high side of the embedded gate driver can be easily provided by the integrated bootstrap diode. MASTERGAN2 has UVLO protection in both the lower and upper drive sections to prevent the power switch from operating in inefficient or dangerous conditions, and the interlock function avoids cross-conduction conditions. The input pin extended range allows easy connection with a microcontroller, DSP unit or Hall effect sensor. The device is packaged in a compact 9x9 mm QFN package. Industrial grade products with an operating temperature range of -40°C to 125°C.

Introduction of ST-ONE:

ST-ONE is the world's first digital offline controller with a secondary side that integrates a programmable offline power controller based on the Arm® Cortex®-M0+ core, built-in 64kB flash memory, high-voltage startup circuit, synchronous rectification controller and USB power delivery (USB-PD) circuit in one package, and is USB-PD 3.1 PPS certified. It is optimized for designs based on a new non-complementary active clamp flyback topology that has higher efficiency than other topologies in high-power designs above 65 W. It is specifically designed for active clamp flyback converters with smart charging solutions (including USB-PD). The device includes an active clamp flyback controller and its startup on the primary side, and a microcontroller and all peripherals required to control conversion and communication on the secondary side. The two sides are connected via an embedded galvanically isolated communication channel. The device is loaded with firmware at the factory, which handles the communication protocols for power conversion and USB-PD, including optional PPS and electronically marked cable management, SCP, FCP and QC 3.0 HVDCP Class B. By using a non-complementary active clamp flyback and dedicated power modes, the device can achieve high efficiency and low no-load power consumption. A dedicated memory stores the default device configuration during the factory process. The user can change or adjust this storage area to meet the final product specifications.

Demo board schematic diagram:

►Scenario application diagram

►Product physical image

► Display board photos

►Solution Block Diagram

►Core technology advantages

1. Fewer external auxiliary devices, integrated 32-bit Cortex M0+ core to realize CNC integrated platform;

2. Ultra-high power density (30W/inch3), which is conducive to product miniaturization;

3. Up to 1MHz switching frequency operation, suitable for GaN and planar transformers;

4. Optimized synchronous rectification digital control, embedded 6 kV electrical isolation;

5. Internal embedded high voltage startup, X-CAP self-discharge circuit and load switch function, various safety protection circuits;

6. Very compact and simple PCB layout;

►Solution Specifications

• Universal input power range: 90 Vac to 264 Vac - frequency 47 Hz to 63 Hz

• Output voltage range: 5 VDC-20 VDC

•PD output: – Five fixed PDOs: 5V@3A, 9V@3A, 12V@3A, 15V@3A, 20V@3.25A.

•Output power: 20 V-3.25 A, 65 W maximum.

• Form factor: 54 mm (length) * 31 mm (width) * 25 mm (height)

• Efficiency: Meets CoC Tier 2 and DoE Level 6 efficiency requirements, with a maximum efficiency of 93.7#0V AC voltage 65W

• Digital control of ACF primary and secondary sides

• Integrated GaN IC MASTERGAN2

• Compact, simplified PCB layout, reducing bill of materials • EMC compliant: CISPR32B/EN55032B

• Planar transformer technology for high power density