Summit Introduces Tiny, Programmable USB/AC Switch-Mode Battery Chargers with Integrated CurrentPath Manager

(Product News, 20 Jul 2009)

Summit Microelectronics has introduced two more members of its third-generation programmable battery charger integrated circuit (IC) family. The SMB136 and SMB137B employ CurrentPath technology, providing dual input source (USB or AC/DC) with arbitration, dual output for system and battery and system operation with a dead or missing battery. Both products support all battery charging standards: USB 2.0 Specification, USB On-The-Go Supplement, USB Battery Charging Specification 1.0, IEEE1725 Standard, Chinese USB Charging Specification, and others. Furthermore, the SMB136 and SMB137B are the only battery charger ICs with CurrentPath to detect the input source type (USB host/hub, AC/DC, etc.) and automatically optimize operation for the fastest and safest battery charging. Both products meet the European Union Memorandum of Understanding, issued on June 29th, 2009, for standardized mobile phone chargers.

The SMB136 and SMB137B are based on a 3MHz, switch-mode architecture, with minimal external components, which allows for very efficient power delivery and extremely compact solution size. High-efficiency operation enables fast charging due to higher output/charge currents, while reduced thermal dissipation improves user comfort, system reliability and Green operation. Furthermore, Summit’s proprietary TurboCharge patent-pending technology enables high charge current, even from relatively low-power sources (example: up to 750mA output from 500mA USB source). As consumer devices continue to employ larger batteries, the SMB136 and SMB137B reduce charge time for consumer convenience.

The SMB136 and SMB137B incorporate CurrentPath functionality to allow both input and output current path control. The SMB136 features one power input (USBIN) that allows USB500/100 or AC/DC (700-1400mA) operation. The SMB137B features two power inputs, one for supporting AC/DC power sources and the second one for supporting USB power sources. Both solutions provide independent output current paths for the system and the battery, allowing the system to turn on with a missing or deeply-discharged battery. This charging configuration reduces the charge and discharge cycles on the battery, thereby extending its operating life. CurrentPath also allows accurate charge termination, since both devices can detect the current flowing into the battery vs. traditional solutions that can only detect the combined current for battery and system.

Both the SMB136 and the SMB137B offer Summit’s proprietary, patent-pending, Low-Battery Recovery (LBR) mode, which provides two benefits: a) enables booting up from a USB1 source and a “dead” battery (common scenario for smart phones and media players) and b) extends battery run time for emergency operation. This is accomplished by running the battery charger in reverse (boost) and providing the system with 4.17V at up to 500mA. Furthermore, this technology eliminates the need for expensive buck/boost regulators in systems with extended voltage range Li+ batteries (less than 3.0V).

“Consumers expect their feature-rich portable electronics to charge quickly, conveniently and to power up instantly, under all conditions. Addressing this need while supporting USB and safety compliancy can be accomplished cost-effectively by Summit’s new CurrentPath battery charging solutions,” stated George Paparrizos, Summit marketing director. “Proprietary technologies, CurrentPath, TurboCharge and LBR significantly reduce charge time, extend run time and improve consumer convenience.”

Like all products in the SMB339 family, the SMB136 and SMB137B also allow true universal USB and AC/DC battery charging. Both solutions incorporate Automatic Power Source Detection to differentiate between a USB 2.0 port and a “USB” AC/DC adapter. Furthermore, the SMB136 and SMB137B offer Summit’s proprietary Automatic Input Current Limit (patent pending), which detects the maximum current capability of the AC/DC adapter and automatically programs the devices’ input current limit accordingly. These two features enable true, universal USB charging and reliable and safe phone operation without the need for additional hardware and software support.

Like its predecessors, both products support USB On-the-Go (OTG) with integrated VBUS power and a current capability up to 500mA, without additional components or cost. A full set of programmable safety features are also integrated to support the strictest safety standards, including IEEE1725 and JISC8714. 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. In addition, the chips’ parametric programmability allows the implementation of sophisticated embedded charging algorithms, further increasing system performance and reliability.

The SMB136 and SMB137B are ideal for any portable device, such as mobile phones, smart phones, portable media/MP3 players (PMP), portable GPS navigation devices, portable game consoles, and digital cameras/camcorders (DSC/DCC). The features and integration of the SMB136 and SMB137B make them especially suited for portable devices that require operation even with a missing battery, utilize higher-capacity batteries and feature very compact industrial designs.

Both products operate with an input range from +3.5V to +6.2V input and safely withstand continuous input over-voltage up to +18V (non-operating), while protecting downstream circuitry. Both the SMB136 and the SMB137B are offered in a tiny 3.0mm x 2.5mm, 30-ball, lead-free chip-scale (CSP) with an operating temperature range of –30C to +85C.