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The Benefits of AC-DC Flyback Topology in Cordless Power Tool Chargers

The Benefits of AC-DC Flyback Topology in Cordless Power Tool Chargers

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The cordless power tool revolution began in 1961 with the release of the first Black & Decker cordless drill. Since then, we have seen explosive growth in the popularity and versatility of these tools, to the point where they are now displacing their corded counterparts in many applications. Like any other battery-powered device, though, power tools eventually need to be recharged - and that's where Infineon comes in with the reference board I introduce in this blog post.

The design of battery chargers has changed a lot over the years. Today, the market trend is for quick, safe and efficient chargers, which at the same time need to be cost-efficient to remain competitive. The cost factor alone makes flyback converters a preferred solution over other topologies in charger applications up to approximately 100 W. But there are other gains as well. If you want to find out which, keep on reading.

To respond to the trends in battery-powered tool charging, we designed a board that helps you to achieve your design targets – cost, performance, reliability, all key points on the checklist. Our new 84 W battery charger is an easy, robust and cost-effective AC/DC reference design. It was developed to enable quick, safe and efficient charging at a competitive price point. The reference board (shown on Image 1) relies on the quasi-resonant (QR) flyback converter topology to deliver optimal efficiency and low EMI operation. With its wide 9 – 21 V output voltage range and minimized bill of materials (BOM), the reference design is easy to implement while still providing all the features modern chargers need like protection against brownouts or outages. It combines the ICC80QSG controller IC and a single 700 V IPN70R450P7S CoolMOS™ MOSFET in one design. The ICC80QSG provides all the protection features needed in modern charger designs with enhancements such as burst mode for very light loads, configurable hysteresis of brown-in and brown-out, and adjustable on-time mapping at valley changing position. On top, the semiconductor components are offered in compact wave-solderable SMD packages (Image 2) for your convenience.


Image 1. Top design image of the 84 W battery charger board.



Image 2. The ICC80QSG flyback controller (left) and IPN70R450P7S CoolMOS™ (right) in the PG-DSO-8 and SOT-223 SMD packages.

The design is over 90% efficient at a full load and dissipates less than 200 mW no-load standby power at 230 VAC. The maximum constant charging current is up to 4 A. This makes it ideal for chargers for cordless screwdrivers, impact drills, jig saws, and robotic vacuum cleaners.

I think, the 84 W battery charger is a good example of how Infineon is using flyback converter technology to create innovative power solutions helping our customers to achieve their goals. We always look for new ways to push the boundaries of what's possible, so that you can keep your products on the cutting edge.

If you want to know more about the products we discussed in this blog post and have a 3D experience of the board, check out these links: