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 the power system. In these systems, the secondary side single-chip microcomputer (MCU) is usually unable to start the system without using an independent biased power supply. Microchip Technology has come up with a new reference design that solves this problem with a MCP1012 high-voltage assisted AC-DC controller that can eliminate independent bias power in many applications. The MCP1012 off-line auxiliary device enables the system to transfer power and duty cycle control to the secondary single-chip microcomputer. By simplifying the design and reducing the size and cost, the controls between the system and the load can be coupled more precisely and purposefully.

                                                                       

The reference design uses patented isolation technology for isolating 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 one device without optical feedback or a separate signal transformer. The new reference design also has the option of taking a more traditional approach, using a planar pulse transformer that works alongside more traditional optical couplers and signal transformers. Secondary side control can be realized by combining the transformer with MCP1012 AC-DC controller and SAM D20 series 32-bit single chip microcomputer.

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

The 15W MCP102 off-line reference design provides the main working element for the 15W off-line 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 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 simulation, Power and interface business unit, said: "Combining the Wurth Elektronik eiSos transformer with Inde-Flux technology with our MCP1012 AC-DC controller and SAM D20 series 32-bit microcontroller creates a unique solution for off-line power management. These devices enable simpler and more reliable complex bidirectional communication between primary and auxiliary components, which are used in many isolation applications utilizing off-line power sources. When the solution is used in systems with secondary side microcontrollers, customers can save up to 60% of the offset power supply area and reduce the offset power bill of Materials cost by more than $3."