Power Management Chip Includes Battery Charger Control

A new power management chip integrates all of the functions required for managing battery power and charger control in digital cellular handsets and other battery powered mobile applications where power and performance requirements are similar. Housed in a 6 mm x 6 mm TPGBA package, the STw4101 includes six LDO analog regulators to supply RF circuits, the baseband chip, audio chip, vibrator and other functions. Two of these LDOs are mask adjustable, two are programmable through an I2C bus and two provide general-purpose fixed supply voltages for 3V and 3.3V supplies. These LDOs require only a 1 µF ceramic capacitor. Also included is a programmable dc/dc stepdown converter that can be used to power the baseband and audio LDOs, increasing efficiency. The STw4101Õs battery charging function controls the gate voltage of an external P-channel MOSFET and performs constant voltage and constant current charging for Lithium ion batteries. This function is an independent state machine capable of managing the battery charge operation independently of the microcontroller. A variety of supporting functions are also integrated in the chip including drivers for a keypad, backlight, buzzer driver and LED indicator switch. A SIM card supply with level shifters is also provided. The STw4101 is priced at $1.90 each/10,000. STMICROELECTRONICS INC., Lexington, MA. (781) 861 2650.