USB charger ICs combines programmability and safety for cost-sensitive applications

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By eeNews Europe

All three products incorporate innovative functionality that allows automatic matching between the AC/DC adaptor’s current capability and the portable device’s charging requirements. Tiny packages and minimum external components allow for small board space and reduced solution cost. Like all Summit’s solutions, digital, non-volatile programmability provides design and system flexibility at no additional cost.

The SMB231/2/3 family of battery chargers is ideal for a wide range of portable devices such as digital still cameras, mobile phones, digital camcorders, wireless headsets, DECT headsets, portable media/MP3 players (PMP), portable GPS navigation equipment, and portable game consoles/controllers.

The SMB231, SMB232 and SMB233 simplify system designs by integrating a robust set of system functions, thereby eliminating a significant number of external components and software requirements. Unlike many traditional charging solutions, these products enable cost-effective and slim industrial designs without compromising performance and safety.

The SMB231/2/3 products incorporate Summit’s CurrentPath functionality to allow 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 functionality also allows accurate charge termination, since the devices can detect the current flowing into the battery vs. traditional solutions that can only detect the combined current for battery and system. The devices also include input current limit which allows USB500/100, USB900/150 or AC/DC operation (300 mA – 1500 mA). An additional option is also available for not limiting input current, thereby supporting high system current levels directly from the input power source, even when the battery is not present.

Like all products in Summit’s 3rd generation family, the SMB231/2/3 devices provide the means to accomplish true, universal USB charging and to meet the various USB industry standards without the need for additional hardware and software support. The products incorporate Automatic Power Source Detection, adhering to the latest USB Battery Charging Specification 1.1. The SMB231/2/3 devices can also detect non-USB compliant wall adapters, thereby maximizing system reliability and performance. A patented Automatic Input Current Limit capability detects the maximum current capability of the AC/DC adapter and automatically programs the devices’ input current limit accordingly. This functionality addresses system issues associated with the fact that “USB” AC/DC adapters can vary widely in current rating, while eliminating the need for additional software support or external components. The resulting improved user experience translates into fewer service calls, fewer merchandise returns and increased subscriber revenue for wireless carriers.

The SMB231, SMB232 and SMB233 claims to incorporate the industry’s widest range of safety features for the battery and the system. All three devices adhere to the Japan Electronics and Information Technology Association (JEITA) safety guidelines, by preventing high charging voltage and/or current levels during certain low and high temperature ranges. Going a step further, battery pack temperature limits, charging voltage and current compensation levels are programmable, resulting in optimized operation for a given battery and system. In addition, the products support IEEE1725 by including dual redundant protection for input/output current and voltage, chip and battery thermal protection, hardware safety timers, battery missing detection and a variety of status and fault registers and indicators. Programmable thermal regulation is also available for preventing system over-heating. The SMB231/2/3 family of products also provides an integrated low-battery voltage detector with programmable voltage thresholds. This function allows the system to receive real-time battery voltage level information and take appropriate actions.

The SMB231, SMB232 and SMB233 operate with an input range from +3.7 V to +6.2 V input and safely withstand continuous input over-voltage up to +20 V (non-operating), while protecting downstream circuitry.

Availability and Pricing

The SMB231 and SMB232 are offered in tiny 2.16 mm x 1.61 mm, 12- and 20-ball, lead-free chip-scale (CSP) packages, while the SMB233 is offered in a small 4mm x 4mm QFN package. All products have an operating temperature range of –30 to +85 degrees C. Available now in production quantities, the SMB231 and SMB232 are priced at $0.80 and the SMB233 is priced at $0.88, each in quantities of 10,000 units.

More information about the SMB231, SMB232 and SMB233 programmable battery charger ICs at


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