Applications Note 71: Design and Manufacturing with Summit Microelectronic’s WLCSP Products
Product Systems Design, October 01, 2010 Smart Battery Management in Medical Devices
by Shadi Hawawini, Senior Applications Engineer, and George Paparrizos, Product Marketing Director, Summit Microelectronics, Inc.
uCSP-20 RoHS/lead-free package with 0.4mm ball pitch
* Patents Pending
INTRODUCTION
The SMB338P 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. Furthermore, the SMB338P is able to automatically adjust input current level by monitoring the status of the adapter voltage.
Unlike conventional devices, the SMB338P’s high-efficiency, switch- mode operation eliminates the thermal problems of conventional linear solutions. Also the buck converter architecture effectively multiplies the input current to increase charge rate for the Li+ cell and uses current limited supplies like USB more efficiently. The SMB338P also supports USB On-the-Go devices by providing the required USB-OTG +5V power supply using the Li-Ion battery as a source.
The SMB338P can switch between USB mode and AC Adapter mode and works seamlessly in conjunction with a USB controller. Charge control includes qualification, trickle-charge, pre-charge, constant current/constant voltage, float voltage and termination/safety settings that are fully programmable via a serial I2C/SMBus, making the device truly a flexible solution. Fast charge current level can be set via I2C (limited in USB mode to ensure 100mA or 500mA input). Built-in is reverse-current blocking to prevent inadvertent cell discharge. The SMB338P offers the option to automatically charge the battery only when the battery voltage is below a selectable “dead-battery” threshold. High frequency operation and integrated power FETs contribute to a reduced external component count and size.
