Microchip has unveiled a reference design based on its MCP1012 auxillary AC/DC controller and Inde-Flux transformer technology licensed to Würth Elektronik eiSos. It is for offline AC/DC power in smart home devices where a secondary side microcontroller is typically not capable of starting a system without a separate bias power supply. The reference design enables the independent bias power supply to be removed in many applications because the MCP1012 offline auxiliary device enables the system to transfer control of the power and duty cycle to a secondary microcontroller. The control between the system and the load can be more precise and purposefully coupled, says the company. In addition, the simplified design reduces size and cost. 

The reference design uses the patented Inde-Flux transformer technology for isolated feedback, which is sold as part of 15W MCP1012 offline reference design. The transformer combines the signal power and signal communication, eliminating the need for optical feedback or an independent signal transformer. A planar pulse transformer can also be used and the design can work with more traditional optocouplers and signal transformers. The secondary side control is enabled through a combination of the transformer and the MCP1012 AC/DC controller and SAM D20 series 32-bit microcontroller.

The MPC1012 primary side auxiliary controller provides for system start up, gating and protecting an offline flyback converter for the secondary microcontroller. Benefits include direct measurement and active regulation of voltage and/or current, high loop bandwidth by direct loop closure and simplified communication for load-referenced systems.

The reference design provides the principal working elements for a 15W offline power design with the firmware necessary to eliminate the auxiliary power supply on the primary side, including eliminating the need for optocouplers in many applications such as appliances and smart speakers.

 Inde-Flux transformer technology, in cooperation with Würth Elektronik eiSos, can be scaled to standard and custom transformer designs for different voltages and power levels as needed.

 The reference design includes a user guide, schematics, bill of materials, design files, firmware and a demonstration unit. The company also offers a fundamental 1W evaluation board, the DT100118 for the MCP1012 AC/DC controller.

 

 

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