We all know the scenario. We decide to buy or upgrade to the latest all-singing, all-dancing phone only to find that our existing charger is incompatible.
Thankfully, the European Commission halted this nonsense and is working toward standardising mobile-phone chargers. The move will have a substantial ecological impact. No doubt, customers will be pleased, too, and mobilephone companies will save some money (although I’ll never understand why these companies didn’t think of this idea themselves).
Understandably, the likes of Nokia and Sony Ericsson have signed up to this EU proposal. And despite the fact that this EU proposal has no influence over the direction taken by America and Far Eastern countries, those territories will get involved as well. Thus, it comes as no surprise to see Apple signing on to the EU charger harmonisation strategy along with Motorola, LG, NEC, Qualcomm, RIM, Samsung, and Texas Instruments.
So how’s it all going to work? Basically, microUSB will become the standard connection technology for all mobile phones, so now it’s up to the electronics industry to make this happen.
Credit must go to STMicroelectronics. It came up with a new IC, the STBP120, that will protect the charging-control circuitry inside mobile phones in case the external charger applies an excessive voltage. How does this help the EU harmonisation plan? Simple. A number of variants of this IC will be available for a range of charging-voltage levels, including USB voltages.
When this device is integrated into a battery-powered product like a mobile phone, it will monitor the voltage from the connected phone charger. If the detected voltage exceeds a preset threshold, an internal solid-state switch opens, preventing the overvoltage from damaging the phone’s internal circuitry.
Four variants span threshold values from 5.375V to 6.02V. These will let electronic design engineers optimise for USB chargers at up to 5.25V or other chargers up to 6.8V. Each device will protect against overvoltages as high as 28V. In normal operation, the internal switch— an N-channel MOSFET—has a very low resistance of 90 mΩ.
Not only does this development help with the universal charger proposition, but phone makers will really like the fact that full production price of the STBP120 in quantities of 1000 is a mere $0.37.