Summit Microelectronics has introduced two more members of its third-generation programmable battery-charger-IC family, the SMB136 and SMB137B. Both employ CurrentPath technology, providing a dual input source—USB or AC/DC—with arbitration, dual output for system and battery, and system operation with a dead or missing battery. The SMB136 features one power input that allows USB500/100 or AC/DC—700 to 1400mA—operation. The SMB137B has two power inputs: one for supporting AC/DC power sources and 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 configuration reduces the charge and discharge cycles of the battery, thereby extending its operating life. The technology 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. The ICs support many battery-charging standards, including USB 2.0 Specification, USB On-The-Go Supplement, USB Battery Charging Specification 1.0, the IEEE1725 standard and the Chinese USB Charging Specification. The ICs are based on a 3MHz switch-mode architecture and use the company's TurboCharge patent-pending technology, which enables a high charge current even from relatively low-power sources. For example, it can output up to 750mA from a 500mA USB source, reducing charge time for the larger batteries. Both ICs also feature the company's proprietary, patent-pending, low-battery recovery mode for booting up from a USB1 source and a dead battery. It also extends battery run time for emergency operation by running the battery charger in reverse (boost) and providing the system with 4.17V at up to 500mA.
