This week on EYE ON NPI (video), we are keeping an eye on safety with Infineon’s 170 W AC-DC Charger Design for E-bikes and Power Tools featuring the Infineon XDPS2201XUMA1 digital flyback controller and Infineon IPA60R280P7SXKSA1 600 Volt, 12 Amp N-Channel power MOSFET. These two best buddies can join forces to help you quickly and safely charge big battery packs such as in e-Bikes and other micro-mobility devices.
If you live near any density of folks, and in a place with well-paved roads, you’ve certainly noticed the increase in e-Bikes, e-Scooters, mono-wheels and other electric ‘person-movers’. In NYC we’ve seen these go from banned to bountiful, as COVID restrictions made food and grocery delivery a bigger business than ever. They’re also popular in lots of countries where folks may not be able to afford cars, motorcycles or even mopeds: an entry-level E-Bike can go for $1000 to $3000 – which is a lot of money but much less expensive than a car. Plus you don’t have to pay for gas or parking, you can lock it up outside or in your yard and charge it over a 120V power plug.
But, about that charging setup … these light vehicles use very big batteries: a common 48V 250 Watt-hours is 26 18650 sized batteries connected in series – with extremely high discharge pulses necessary if you want to haul around a 75 lb bicycle plus a 200 lb cargo of human plus groceries. Also important is the ability to charge quickly. If you’re using the e-Bike for a courier job, or you take it work, and you need to charge it in order to get back home, you don’t want to wait around 16 hours. But that also means that bicycles are often charged unattended, and that could mean that a poor engineering job on the charging circuit can lead to tragedy . So don’t cheap out on your design, and don’t try to invent high power electronics layouts and specifications when you can rely on experts who’ve already done the work and created a reference you can base your product on
Here’s the design considerations: we have to charge this battery quickly, but also safely, and without generating a lot of heat, and directly from the wall outlet. Quickly means we need to push a lot of current out – up to 4 Amps continuously. Directly from the wall outlet means we’ll want a direct 120-220V AC input, to the ~48V output. To avoid generating heat we definitely need to use very low RdsOn FETs, and reduce the switching frequency when we can to optimize power-transfer efficiency. Since we’re dealing with mains, we need to have an isolated output so there’s no risk of electrocution through the battery casing. Normally this would point to using an AC/DC flyback converter since we need to have high voltage input, and isolated output. But if you want to do better, and smaller – a hybrid flyback gives you the size and efficiency of a buck-converter with the low cost and isolation of a fly back: with inductor-stored power for high voltages and capacitor-stored power for low voltages.
The Infineon XDPS2201XUMA1 digital flyback controller is really a jack-of-all trades chip. It’s in a easy-to-implement SOIC and can provide 170W output without a huge complex BOM. Inside is an SoC which can be configured during production over UART to set parameters, output voltages and cut-offs. Thus, you get the reliability of an hardware power management chip with the configurability of a firmware solution. The MFIO multi-function IO pin can also send out error codes so that users of your product can at least know what might be going wrong before tossing your product or contacting customer support. Infineon also has evaluation boards and known-good layouts and component selections so that you can be confident that you will not have to go through dozens of revision to pass EMI and UL certification steps.
The Infineon XDPS2201XUMA1 digital flyback controller and Infineon IPA60R280P7SXKSA1 600 Volt, 12 Amp N-Channel power MOSFET are both in-stock right now for immediate shipment from DigiKey. Whether you are designing a pocket-sized USB wall adapter or a chonky eBike charger, the XDPS2201 chip will reduce your BOM cost, physical size, heat dissipations and power usage. Place your order today and you’ll get Infineon’s industry-leading products to get your design on the road by tomorrow afternoon.