The SMB346 and SMB347 programmable lithium-ion (Li-ion) battery-charger ICs from Summit Microelectronics deliver up to 2.5-A charge/system current with the company’s dual-input/dual-output CurrentPath technology for operation with dead or a missing battery.

The dual inputs accept USB and ac-dc with automatic selection and support for all battery-charging standards, including USB 2.0, USB on-the-go supplement, USB battery-charging specification 1.2, IEEE1725, and the Chinese USB charging specification. 

Thanks to the CurrentPath technology, according to the company, the SMB346 and SMB347 are the only battery-charger ICs that can detect the input source type and automatically optimize operation for the fastest and safest battery charging.

Both ICs are based on a 3-MHz, switch-mode dc-dc architecture with minimal external components, which allows for more than 90% efficient conversion and an extremely compact solution size, Summit says. They enable fast charging due to higher charge currents while their reduced thermal dissipation is designed to improve user comfort, system reliability, and green operation.

The company’s TurboCharge technology is designed to enable high charge current even from relatively low-power sources, such as up to 750-mA output from a 500-mA USB source. As consumer devices continue to use larger batteries, the ICs reduce charge time for consumer convenience. In fact, the company claims they enable the first solution for smart phones that charges under an hour.

The SMB346 and SMB347 simplify system designs by integrating a robust set of system functions, eliminating a significant number of external components and software requirements. They also offer a wide programmable range of parametric and functional configurability for optimized designs and faster times to market. Housed in 2.46- by 2.96-mm, 30-ball, lead-free chip-scale packages (CSPs), they enable slim industrial designs without compromising performance or safety.

The CurrentPath technology offers independent output current paths for the system and the battery, allowing the system to power up with a missing or deeply discharged battery. It also reduces the charge and discharge cycles on the battery to extend its operating life. It allows accurate charge termination since the devices can detect the current flowing into the battery, unlike traditional solutions that can only detect the combined current for the battery and system

The ICs boast an input current limit that enable USB500/100, USB900/150, or ac-dc operation (300 to 2500 mA). According to the company, they provide the means to accomplish true, universal USB charging and to meet the various USB industry standards without additional hardware or support.

The SMB346 and SMB347 also incorporate automatic power source detection, adhering to USB Battery Charging Specification 1.2. They can detect non-USB-compliant wall adapters as well, maximizing system reliability and performance.

Their 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 result, according to Summit, is an improved user experience with fewer service calls and fewer merchandise returns with increased revenue for wireless carriers.

Both devices support USB On-the-Go (OTG) and MHL/HDMI with integrated VBUS power and a current capability up to 750 mA without additional components or cost. An integrated full set of programmable and redundant safety features support the strictest safety standards, including JEITA, IEEE1725, and JISC8714. These include dual redundant protection for I/O 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 chips’ parametric programmability allows the implementation of sophisticated charging algorithms, further increasing system performance and reliability, Summit says. Programmable thermal regulation is also available for preventing system overheating. An integrated low-battery voltage detector with programmable voltage thresholds enables the system to receive real-time battery voltage level information and take appropriate actions.

The SMB347EV design kit includes menu-driven Microsoft Windows GUI software to automate programming tasks as well as the necessary hardware to interface to the USB port of a laptop or PC. After design and prototyping are complete, the kit automatically generates a HEX data file that can be transmitted to Summit for review and approval. The company then assigns a unique customer identification code to the HEX file and programs the customer’s production devices prior to final electrical test operations, ensuring proper operation in the end application. 

The SMB346 and SMB347 operate with an input range from 3.7 to 6.2 V and safely withstand continuous input over-voltage up to 20 V (non-operating) while protecting downstream circuitry. They operate from –30°C to 85°C. Available in production quantities, the SMB346 costs $1.27 and the SMB347 costs $1.36, both in quantities of 10,000 units.

Summit Microelectronics
www.summitmicro.com