New Industry Products

Summit Micro Unveils Digitally Programmable Linear Li-Ion Charger IC

June 11, 2007 by Jeff Shepard

Summit Microelectronics has further expanded its family of Programmable Battery Charger integrated circuits (ICs) with the introduction of the SMB139 single-cell, Li-Ion and Li-Polymer linear battery charger. The device’s battery charging profile is said to be able to be configured to adapt easily to new system designs and battery types. Furthermore, the SMB139’s tiny size makes it suitable for portable applications that require the smallest possible charging footprint. The SMB139 integrates many protection features, thereby ensuring what the company claims is the highest level of safety and eliminating the need for additional external components.

The SMB139’s tiny 1.3mm x 2.1mm chip-scale package is said to deliver a charging solution that occupies significantly smaller board space than traditional implementations. The flexible programmability with the I²C interface is said to allow convenient parametric and functional control and provides unlimited design flexibility, both in-system and during the development stage. The SMB139’s chip-scale package is said to allow for the integration of a higher number of features, including critical charging protection functionality.

The SMB139 comprises a highly integrated, 210mA linear charging solution that utilizes a fully programmable algorithm for single-cell Li-Ion and Li-Polymer cells. All charging parameters – pre-charge/fast-charge/charge termination current, cell float/pre-charge voltage, battery temperature/timer safety limits – are configurable via the I²C/SMBus interface, enabling a wide variety of algorithms without hardware changes. Real-time adjustment of the charging profile also minimizes charging time and maximizes safety.

The SMB139 can be programmed either dynamically (real-time using volatile registers), by a microcontroller and software via the I²C/SMBus port, or statically (pre-programmed using non-volatile registers). If the static programming mode is used there is no need for software to access the I²C/SMBus interface and the SMB139 functions independently as a customized, but parametrically fixed solution. Static configurability allows the same product to be used in different system designs and/or with different battery types and technologies, resulting in significantly lower qualification/inventory costs and sourcing risks.

The SMB139 operates from a +4.35 to +6.5V input, making it well suited for either USB or ac adapter power sources. However, for applications where the ac adapter may be poorly regulated and/or an aftermarket or counterfeit product is used, the SMB139 will tolerate +10V inputs without damage. Ensuring long battery life when not connected to a dc power source, the reverse leakage current is less than 2µA. In addition, when the I²C/SMBus port is not utilized for charge control/monitoring, the SMB139 provides a CHGSET control pin for real-time, two-level charge current configuration, as well as a STATUS output to drive an LED for indicating charge status and fault conditions.

The SMB139 is well suited for a wide range of space-constrained handheld consumer devices such as Bluetooth headsets, stereo headsets, flash-based portable music players, noise-cancellation headphones, robotic toys and wrist watches/PDAs. In particular, it is a well suited charging solution for applications that utilize small-capacity Li+ batteries and/or use a single USB connector to provide both data and power.

The SMB139 has an operating temperature range of -30 to +85°C and is available in the 1.3mm x 2.1mm 15-ball chip-scale (CSP™) package that is lead-free and RoHS-standards compliant. Available now in production quantities, the device is priced at $0.85 each in quantities of 10,000 units.