Introduction

Texas Instruments introduces the UCG28826, a high-frequency, quasi-resonant (QR) flyback converter with an integrated 700V GaN high-electron mobility transistor (HEMT). Featuring an ultra-low Rds(on) of 170mΩ, this device is designed for efficient AC-DC power conversion up to 65W, making it ideal for USB power adapters, industrial power supplies, and server auxiliary power systems. The self-biasing and auxiliary sensing mechanism eliminates the need for additional auxiliary windings, simplifying circuit design and enhancing efficiency.

TI UCG28826

The UCG28826 significantly enhances system performance by integrating a high-performance GaN transistor and reducing component count. Its self-biasing mechanism removes the need for auxiliary windings, reducing cost and complexity. Additionally, the cycle-by-cycle current limit and multiple fault protections ensure robust operation and fast fault response, protecting the system from potential damage. The flexible resistor-based configuration allows engineers to fine-tune system parameters without extensive redesigns, making it highly adaptable for different applications.

The UCGC28826 integrates multiple advanced features to enhance performance, reduce system cost, and improve reliability:

1. High Efficiency and Low Power Consumption
   1. Ultra-low standby power (<30mW)
   2. Dynamic mode transition (QR/DCM/CCM) for high efficiency across various load conditions 
   3. Valley switching and frequency dithering to optimize efficiency and EMI performance 
   4. Frequency foldback and burst mode for light-load efficiency 
2. Integrated Components for Lower BOM Cost
   1. Eliminates auxiliary winding with built-in self-biasing 
   2. Integrated input/output voltage sensing for enhanced control 
   3. Built-in current sensing and HV startup circuit to simplify external components 
   4. X-cap discharge circuit for added safety and compliance 
3. Comprehensive Protection Mechanisms
   1. Over-temperature protection (OTP), Over-voltage protection (OVP), and Short-circuit protection (SCP)
   2. Cycle-by-cycle current limit for robust operation 
   3. Two-level over-power protection (OPP) with line voltage sensing (LPS compliance)
   4. Brown-in/out protection and open feedback protection
4. Flexible Configuration via Resistors
   1. Selectable switching slew rate and clamping frequency settings
   2. Adjustable fault response (latch or auto-restart)
   3. Configurable X-cap discharge and CCM mode disable
   4. Adjustable peak current ratio and dithering amplitude for EMI reduction 

Applications

With its high efficiency and integrated GaN technology, the UCG28826 is ideal for various high-power density applications, including:

• USB Power Delivery (PD) Adapters for portable electronics 
• USB wall outlets and docking stations
• Industrial DIN rail power supplies
• Server auxiliary power supplies

Summary

Texas Instruments' UCG28826 is a next-generation solution for high-efficiency AC-DC conversion, combining integrated GaN technology, advanced protection features, and configurable operation modes. By eliminating auxiliary windings and reducing BOM cost, this device simplifies system design while enhancing reliability and efficiency, making it an excellent choice for modern power supply applications.