The SMB137B is a programmable single-cell lithium-ion / lithium-polymer battery charger designed for a variety of portable applications. The device provides a simple and efficient way to charge high-capacity Li-Ion batteries via a USB or AC adapter input. Unlike conventional charging devices, the SMB137B's high-efficiency switch-mode operation eliminates the low charge current and thermal problems of conventional linear solutions. In addition, the switching architecture in conjunction with programmability enables dramatically faster charging - TurboCharge™ mode - from current limited inputs such as USB.

The SMB137B can switch between USB mode and AC Adapter mode and works seamlessly in conjunction with a USB controller. Also the SMB137B can manage two outputs independently: battery charging and system power. This allows immediate system operation even under missing/deeply discharged battery conditions. Also in the case of a low battery and insufficient/missing input supply the SMB137B can run its switching regulator in reverse to support "Low Battery Recovery" mode (+4.17V @ 500mA) or USB "On the Go" power (+5V @ 500mA).

Charge control includes input current limit (supporting USB2.0), trickle charge, pre-charge, constant current/constant voltage, float voltage and termination/safety settings that are fully programmable via a serial I2C/SMBus and stored in non-volatile memory making the device truly a flexible solution. Fast charge current level can be set via I2C (limited by the input current settings). An Enable (EN) pin is also provided for suspending charging and/or sleep mode. Built-in reverse-current blocking prevents inadvertent cell discharge.

The SMB137B also offers a wide variety of features that protect the battery pack as well as the charger and input circuitry: over-current, under/over-voltage, safety timers and thermal protection. Accurate 1.0% battery float voltage control ensures complete charging and improves battery capacity utilization. Status can be monitored via the serial port for charge state and fault conditions. In addition, the STAT output can be used to signal charge status. Operating voltage is specified from +4.35V to +6.0V with +18V non-operating input tolerance. The SMB137B is available in an ultra-compact CSP-package and is rated over the –30C to +85C temperature range.