New Industry Products

Summit Introduces Battery Charger To Enable True Universal USB Charging

October 07, 2008 by Jeff Shepard

Summit Microelectronics has introduced its third-generation programmable battery charger integrated circuit (IC) for single-cell Li-Ion and Li-polymer powered systems. The company claims that the SMB339 integrates the largest feature set in the industry, including compatibility with all relevant industry standards: USB 2.0 Specification, USB on-the-go supplement, USB battery charging specification 1.0, IEEE1725 Standard, Chinese USB charging specification, and others.

The company claims that this charging solution automatically adapts to and delivers the fastest battery charging from any power source (USB host/hub, ac-dc, etc.) without the software required in typical implementations. Additionally, high integration is said to reduce bill-of-material count/cost and solution size to levels comparable to other linear charging solutions, while cutting power dissipation by 80%.

The SMB339, based on a high performance 3MHz switch-mode architecture, is described as the industry’s most integrated single-cell Li-Ion charger. The device’s high-efficiency operation, coupled with Summit’s proprietary TurboCharge patent-pending technology, allows for highest charging current (up to 750mA from 500mA USB source) and lowest power dissipation. This is said to allow for slim industrial designs and significantly faster charging times; two valuable differentiating factors for handset and other consumer products.

The SMB339 is said to be the industry’s first solution that allows true universal USB and ac-dc battery charging. First, the automatic power source detection differentiates between a USB 2.0 port and a "USB" ac-dc adapter. This allows the charger to comply with the USB 2.0 100/500mA limits, but also to draw higher current levels from an ac-dc wall adapter. Subsequently, since ac-dc adapters can vary widely in current rating, automatic input current limit (patent pending) detects the maximum current capability of the ac-dc adapter (can be as low as 300mA for Chinese chargers to more than 1.5A per USB charging specification) and automatically programs the SMB339’s input current limit accordingly. The SMB339 performs these functions independently, without the need for external components or system software operation. These two features ensure true USB compliance while providing the fastest safe charging from any source (including ac-dc adapters), giving end-users the best charging performance in any situation.

The SMB339 is also capable of providing USB On-The-Go (OTG) power support, without the need for additional external components. The device has the ability to reverse its power path when not charging, thereby supplying 5V and up to 500mA to VBUS, exceeding the USB OTG Supplement Specification. The chip’s parameters are programmable in non-volatile and volatile memory for power-up configuration and in-system adjustments via the I²C host interface. This provides maximum design flexibility to address a variety of system and battery designs and allows the implementation of sophisticated embedded charging algorithms.

A wide variety of programmable safety features are also integrated to meet the strictest safety standards, including IEEE1725. These include dual redundant protection for input/output current and voltage, chip and battery thermal protection, hardware and software safety timers, battery missing detection and a variety of status and fault registers.

The SMB339 is suitable for a wide range of portable devices such as mobile phones, smartphones/PDAs, portable media/MP3 players (PMP), portable GPS navigation, portable game consoles, and digital cameras/camcorders (DSC/DCC). The features and integration of the SMB339 make it especially suited for devices that include a USB interface because it is said to allow a tiny, low-cost industry-standard micro USB connector to be the primary data and power/charging interface.

The SMB339 operates with an input range from +3.5 to +6.2V input and safely withstands continuous input over-voltage up to +16V (non-operating), while protecting downstream circuitry. The SMB339 is offered in a tiny 2.3 x 2.0mm, 20-ball, lead-free chip-scale (CSP) package with an operating temperature range of -30 to +85°C.

Available now in production quantities, the SMB339 is priced at $1.24 each in quantities of 10,000 units.