Microchip introduces a new power supply control reference design to realize secondary single-chip control of the main power supply

     In modern off-line AC-DC power solutions, programmability and adaptive control provide the flexibility and intelligence needed for smart home devices to better connect with power systems. In these systems, the secondary single-chip microcomputer (MCU) is usually unable to start the system without using an independent biased power supply. Microchip has introduced a new reference design that solves this problem with the MCP1012 high-voltage assisted AC-DC controller, which eliminates the independent bias power supply in many applications. The MCP1012 off-line auxiliary device enables the system to transfer the power and duty cycle control to the secondary single chip microcomputer. By simplifying design, reducing size and cost, control between system and load can be more precisely and purposefully coupled.

     The reference design uses patented isolation technology to isolate feedback. The patented isolation technology, called Inde-Flux Transformer technology, has been licensed to Wurth Elektronik eiSos. The Inde-Flux transformer (part number 750318659) is the first transformer made by Wurth Elektronik eiSos utilizing the patent and will be sold as a component of Microchip's 15W MCP1012 off-line reference design. This transformer combines signal power and signal communication in a single device without optical feedback or a separate signal transformer. The new reference design also has the option to take a more traditional approach, using a flat pulse transformer that works alongside more traditional optocouplers and signal transformers. Secondary side control is achieved by using this transformer in combination with Microchip's newly launched MCP1012 AC-DC controller and SAM D20 series 32-bit microcontrollers.

     The MPC1012 primary side auxiliary controller provides the functions of system startup, gating and protection of off-line flyback converter for the secondary microcontroller. The device has a range of features such as direct measurement and active voltage or current stabilization, high loop bandwidth through direct closed loop, and simplified communication of load reference systems.

     The 15W MCP102 Offline reference design provides the main working elements for the 15W offline power supply design and is equipped with the necessary firmware to eliminate the primary side auxiliary power supply. This can reduce system complexity, including eliminating the need for optocouplings in many applications, such as home appliances and smart speakers. With the support of Wurth Elektronik eiSos, Inde-Flux transformer technology can be extended to standard and custom transformer designs with different voltages and power levels as needed.

     Rich Simoncic, senior vice president of Microchip's analog, Power and Interface business unit, said: "Combining the Wurth Elektronik eiSos transformer using Inde-Flux technology with our MCP1012 AC-DC controller and SAM D20 series 32-bit microcontrollers creates a unique solution for offline power management. These devices enable simpler and more reliable complex bidirectional communication between primary and auxiliary components, which are used in many isolated applications utilizing offline power supplies. When the solution is used in systems with secondary side microcontrollers, customers can save up to 60% of the biasing power area and reduce biasing power bill of Materials costs by more than $3."