The Ministry Information Industry (MII) of China enforced all mobile phone manufacturers to comply with new issued standard for phone charger interface, which is called YDT 1591-2006 mobile phone charger and interface requirement and testing method.
Standard Mobile Phone Charger with USB Port http://dev.emcelettronica.com/print/51734 Your Electronics Open Source (http://dev.emcelettronica.com) Home > Blog > allankliu's blog > Content Standard Mobile Phone Charger with USB Port By allankliu Created 14/04/2008 - 05:23 BLOG Usb Background The Ministry Information Industry (MII) of China enforced all mobile phone manufacturers to comply with new issued standard for phone charger interface, which is called YD/T 1591-2006 mobile phone charger and interface requirement and testing method. Before launching this standard, every mobile phone manufacturer has own power adapter interface with different electrical and physical specifications. Due to business and technical reasons, some vendors even offer different power adapters for same brand! This standard unifies the AC/DC power adapter interface with standard USB type A output on 5V DC, therefore new mobile phones from different vendors can share common adapters or be charged with standard PC USB port. The Mobile users can just carry one USB cable and phones on the go, since the USB port is available anywhere. It is anticipated that this approach can reduce power adapters in retail package, and reduce overall BOM cost and the pollution with the abandoned mobile phones. I do believe a fact that the new standard will influence other portable device projects as well. Check out the photo taken about my electronics devices. My Sony Ericsson K750 has regular travel charger and USB kit. The USB kit can charge mobile phone via both PC USB port and a small USB power adapter. And my Shaver can use USB power adapter as well. BTW, my shaver works on PC USB port as well, but overdraw the current over 500mA. The PC pops up a warning when I switch on the shaver. The idea behind it is great. However it brings some technical issues for mobile phone manufacturers. Based upon this standard, the AC/DC adapter is a power adapter offers 5V with 5% tolerance. The wall mount adapter can offer current ranges from 300mA to 1800mA, and the PC USB port can offer 500mA. The charger circuit is located inside the mobile phone. The charger design should consider thermal management, over current, over voltage, and PCB size and mounting location. 1 din 3 01.05.2008 15:51 Standard Mobile Phone Charger with USB Port http://dev.emcelettronica.com/print/51734 Embedded Charger inside Mobile Phones There are different solutions for charger circuit, a) discrete components, b) charger IC, and c) a PMU with external power component. The discrete components based solution is very flexible and easy for thermal management, while its shortcoming is high BOM cost and hard to reduce the PCB size. The charger ICs from different vendors are highly integrated, easy to fit PCB and housing, but it is usually working on certain nominal current. The latest approach of PMU with external power component now is dominating the internal charger application, which offers enough flexibility and can meet PCB size requirement. The external power component working with PMU might be a FET, dual FETs, a BJT or a FETKY. If a FETKY is selected as the external component with a PMU, it will introduce voltage drop as the charging current get through. It can introduce 400mV drop on 500mA. More charging current, more voltage drop is generated. It is not a good solution to use FETKY in both work wall mount and USB port power sources. Dual FETs are good enough for this application, the benefits of these components are: jam the reverse current, allow to charge Bluetooth accessories with reverse current and low Rds(on). Additionally, frequently switching will generate heat on components and reduce the life cycle of them. The dual FETs approach can offer extra thermal sensor feature available for thermal control to support high efficient charger and thermal protection. Effective OVP According to MII's standard, mobile phone charger should embed OVP (Over Voltage Protection) feature as well. It should activate the protection for inside electronics circuit in case the power voltage is higher than 6V. The component selection criteria are switching speed and extra ESD protection. NCP348/NCP360/NCP361 from Onsemi offer different configurations for OVP feature. These ICs can isolate the internal circuit with external AC/DC adapter, with smaller PCB area and high precision voltage measurement. They offer ENABLE and STATUS/FLAG pins, plus extra over current protection and much more features. More Issues Since the new designed mobile phones should be charged via PC USB ports as well, we have to consider USB current limitation for this embedded charger as well. It is not allowed to deliver the maximum specified current (500mA) without software negotiation. Initially the phone is only allowed to draw 100mA. It may request more current from host in units of 2mA up to 500mA. But in practice the PC has no direct control over current drawn from the USB 2 din 3 01.05.2008 15:51 Standard Mobile Phone Charger with USB Port http://dev.emcelettronica.com/print/51734 port. PCs often limit the USB current only through the use of passive automatically resettable fuses. In order to setup a connection for current negotiation, the designer can link D+/Dconnections between host controller and mobile phone controller according to regular USB design. The PMU will not get involved in this communication design. It is just a power management IC. The current negotiation is fully under control of software, especially the mobile phone software. You might find a fact that Windows Mobile based smart phones can not get charged via PC USB ports without installation ActiveSync or via a wall power adapter. Because Windows mobile directly shuts off the charging circuit without negotiating about current with host controller. But there are some hacks to enable USB charging without ActiveSync or on the other way, disable USB charging with ActiveSync. All of these hacks are software approaches. Those prove my point, that the USB charging is under control with mobile phone software anyway. Latest Updated Recently MII announced another new standard for PIM information exchange of mobile phones. This new standard is called UDX with two technical requirement specifications, YD/T 1760.1-2008 (Digital mobile terminal peripheral interface data exchange) and YD/T 1760.2-2008 (Technical requirement of data exchange format). All new models can talk with each other via USB-OTG or with PC standard PIM software. Mobile phones are turning into real plug and play devices, no driver installation is required any more. Trademarks Source URL: http://dev.emcelettronica.com/standard-mobile-phone-charger-usb-port 3 din 3 01.05.2008 15:51
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