Technical Article

Dynamically Configurable Off-Line Switcher IC for Higher Application Flexibility

June 29, 2018 by Jason Yan

This article discusses Power Integrations Switcher ICs offering significant advantages of programmability, configurability, and adjustability.

InnoSwitch3-Pro integrated switcher ICs enable digital micro-stepping of voltage and current for precise battery charge control and elimination of DC-DC post-regulators, and provide 65 W power output at efficiency levels of up to 94% across line and load conditions.


A Programmable, Configurable, and Power-Adjustable Solution

InnoSwitch ICs previously released by PI are mainly dedicated to high efficiency and integration. In addition to these features, the new InnoSwitch3-Pro IC family offers significant advantages of programmability, configurability, and adjustability.


InnoSwitch3-Pro: Digitally Programmable Power Conversion
Figure 1. InnoSwitch3-Pro: Digitally Programmable Power Conversion


The newly-released InnoSwitch3-Pro enables programmable power conversion, featuring an advanced control engine of the digital interface (I2C). The device realizes accurate dynamic step control (in 10 mV voltage and 50 mA current) over the output voltage and current through a simple dual-line I2C interface, providing constant voltage (CV), constant current (CC), and constant power (CP) output features. Its protection function is also configurable, supporting enabling, disabling, shutdown, auto-restart, and threshold triggering operations. For example, generally, there are two protection response mechanisms for short circuits. One is a complete turn-off and the other is hiccups (repeated restarts). These two protection response mechanisms can be configured externally via InnoSwitch3-Pro. Once a fault occurs, the device enters a specified protection mode based on the configuration, while a traditional power supply cannot realize it, because the protection response mechanism is fixed once the power supply is manufactured. In this way, InnoSwitch3-Pro offers flexibility in a great extent.


 Programming Interface
Figure 2. Programming Interface


The new devices may be paired with a microcontroller or take inputs from the system CPU to control and monitor the off-line power supply. Applications include virtually any rapid-charging protocol, including USB Power Delivery (PD) 3.0 + PPS, Quick Charge 4/4+, AFC, VOOC, SCP, FCP and other industrial and consumer battery chargers, dimmable LED ballast drivers and field-configurable industrial power supplies. The new InnoSwitch3-Pro IC adopts both primary and secondary controllers, as well as the I2C interface. In addition, it uses FluxLink™, a high-speed digital communication technology developed by PI, to bridge the isolation barrier. Certified by CQC, UL, and TUV, this new IC can safely bridge across the primary power isolation barrier. It also provides synchronous rectification, quasi-resonant switching and a precise secondary-side feedback sensing and control circuit. Its InSOP-24D package provides a slim solution that features high heat dissipation efficiency and extended creepage (>11.5 mm) and clearance between primary and secondary sides for high reliability, surge protection and ESD robustness. The enhanced flexibility of I2C is also significant. The AC-DC power conversion market is undergoing rapid transition with system designers needing a programmable solution that can adapt to various fast-charging protocols, including the recently-completed USB PD 3.0 + PPS specifications. The ability to precisely control the output voltage and current of a power supply over a wide range is also useful for designers of specialized applications with smaller production runs, as they can easily configure a single board design for multiple product SKUs using software either at manufacture or during installation. It addresses a wide range of applications, supporting almost all rapid-charging protocols, covering smartphones, notebooks/laptop, tablets, smart speakers and so on.


Transforming the Traditional Mode of Power Supply Production

Traditional power supplies are designed and manufactured based on the output specifications and features by SKU. For example, some power supplies require a 5V CV/CC output, some a 12V CV output, and still others CC output for LED lighting. Different output specifications require different designs and dedicated certification. In this case, the production line needs to adjust the processing and material for each SKU. With InnoSwitch3-Pro power supply solution, only one production line is needed. The power supply output specifications and features can be adjusted through programmable control. For different customer requirements, only configuration is involved. This greatly improves production efficiency and speeds up customer requirement response. Importantly, safety certification needs only to be done for once.


Disrupts the Power Supply Manufacturing Model Multiple Custom Power Supplies from One Design

Figure 3. Disrupts the Power Supply Manufacturing Model Multiple Custom Power Supplies from One Design


Thanks to this programmability, InnoSwitch3-Pro can be easily used for ballast applications requiring multiple output voltage levels and satisfy the power supply protection and safety requirements of different regions. For example, the output latching protection mode required by Japanese customers. For non-charging applications, its output programmability enables the implementation of different output requirements using only one power supply design, which greatly shortens the design period and reduces the cost of production, certification, and warehousing. To be specific, InnoSwitch3-Pro can implement different power supply specifications of customers with one design.

The configurability of InnoSwitch3-Pro will facilitate the production of high-performance power supplies in high efficiency and low component counts. With its configurability implemented through I2C communication and low-cost microcontrollers, InnoSwitch3-Pro can deliver programmable output based on load requirements, suitable for rapid-charging applications. The specifications can be configured during manufacture in the production line. The specifications and protection features are adjustable by the client even in the field.

PI also provides a comprehensive set of design-supporting tools, reference design (DER-641), design guide and manual, programming support, and PI Expert design software for this new IC family to help users complete design more easily and quickly. By using InnoSwitch3-Pro off-line switcher IC, BOM count of power supplies is significantly reduced and design complexity is dramatically simplified. A comprehensive API library for object-based programming is also available.


About the Author

Jason Yan works as the Senior Technical Manager at Power Integrations.


This article originally appeared in the Bodo’s Power Systems magazine.