Summit Microelectronics’ SMB137 programmable battery charger IC was designed for mobile consumer electronics. Dual (USB or AC/DC) inputs and outputs (System or Battery) with CurrentPath(TM) automatic arbitration allow system operation with any input source, any battery charge state, or even missing battery. Proprietary TurboCharge(TM) technology yields dramatic reductions in charge time, power dissipation, and solution size compared to conventional charger solutions. The ultra-small solution size, combined with Micro-USB data/power support, enables ultra-thin devices with the convenience of USB battery charging.
Integrated features such as USB On-The-Go (USB-OTG) power and Low-Battery-Recovery(TM) (LBR) bring new levels of mobility and convenience to consumers. The I²C interface enables sophisticated software programmability, while the embedded nonvolatile configuration provides a tremendous degree of design flexibility without the need for software development.
The SMB137′s CurrentPath(TM) input/output controller intelligently arbitrates between dual inputs and applies the appropriate current limit (100mA/500mA or 700-1400mA) depending on the source – USB or AC/DC. At the output the current is steered between the system output and the battery charger with the system taking priority over the charger. When operating from battery power, the “active diode” function automatically connects a low impedance path from the battery to the system output for high efficiency operation, extending battery life. All the input/output control functions are governed by programmable parameters held in non-volatile configuration memory.
The fully integrated switch-mode charger outputs up to 1.5A with over 90% typical efficiency, maximizing charge current while minimizing power dissipation – up to 50% to 80% improvement over typical linear charging solutions. Patent-pending TurboCharge(TM) technology automatically boosts output current while precisely limiting input current for USB 2.0 compliance – up to 750/150mA charger output from a 500/100mA USB 2.0 port or 1.5A from a 1000mA AC/DC adapter. USB 2.0 enumeration support and I²C programmability facilitate emerging standards such as the Micro-USB connector and facilitate a new generation of compact industrial designs. Additionally, USB standardization significantly reduces BOM cost versus proprietary multi-pin connectors and frees consumers from the bulky AC/DC wall adapter.
USB functionality is enhanced with proprietary technology that supports USB On-the-Go and Low-Battery-Recovery(TM) (LBR). The SMB137′s step-down converter, that normally operates in “forward mode” to charge the battery, can operate in reverse to boost the battery voltage to +5V for USB-OTG or +3.9V to +5.0V for LBR(TM). USB-OTG power allows two USB devices to connect to each other without the presence of a PC. This feature greatly enhances the mobility of USB devices by allowing truly mobile data exchange. LBR(TM) mode is another exclusive Summit technology that eliminates what is commonly known as “dead battery trap” – a condition where a battery is so discharged (typically below 3.3V) that it cannot power-up the system. Unlike competing solutions no additional external boost circuit components are required for either USB-OTG or LBR(TM) modes.
An I²C digital interface and volatile/non-volatile programmability allow for a high degree of flexibility in power management parameters. The SMB137 can be “custom” programmed in manufacturing and used “standalone” without the need for system interaction. Alternatively, with the I²C interface, virtually all parameters can be adjusted “on-the-fly” to optimize battery charging with software depending on system needs. Parameters that are programmable include: input and output current limiting, pre-charge/fast-charge/termination current settings, float voltage, pre-charge voltage threshold and OTG/LBR current limit. The SMB137 operates with an input range from +4.35V to +5.5V input and tolerates input over-voltage up to +16V (non-operating). The operating temperature range is –30°C to +85°C.
The SMB137 is compliant with existing and emerging safety and standards for portable devices including a host of safety features: input current limit, dual independent output current limits, input and battery over-voltage protection, battery and chip thermal protection, charge safety timeouts, trickle charge, software watchdog timer and status/fault monitors. With these features the SMB137 is compatible with common standards such as USB 2.0, IEEE1725, and the new China USB Charging Specification.
The SMB137 is offered in a 3.3mm x 3.6mm 30-ball chip-scale (CSP) package which is lead-free and RoHS-standard compliant. The SMB137 is priced at $2.30 each in quantities of 10,000 units.