DS2731

Rev 1; 1/09 Cache-Memory Battery-Backup Management IC General Description The DS2731 is a complete power-management solution for modular backup applications. It is well-suited for 2.5V and below memory bus voltages, with an input voltage of 12V. The DS2731 includes an internal MOSFET switching power stage for charging a one-cell lithium chemistry battery. It has a fully integrated synchronous buck regulator capable of supplying up to 450mA of cache backup supply current, and the necessary logic and power devices for handling the switchover from system power to battery power. The battery charging method of the DS2731 is constant current/constant voltage (CCCV). Output voltage can be margined from 3.8V to 4.6V using a resistordivider. Charge is terminated when the charging current falls below 5% of full charge current. Switchover to battery backup is initiated by an internal comparator and occurs automatically when a sensed-input voltage drops below 2.93V. At light loads, the 2MHz internal synchronous buck regulator operates in burst mode for maximum efficiency. All nonessential functions of the DS2731 are disabled while supplying holdup current to the cache memory, and the IC goes into very low-current dormant mode when the battery voltage drops below a user-settable threshold. The DS2731 keeps track of charge status and signals the user through open-drain I/O pins that can be used to drive LEDs. o Lithium Chemistry CCCV Charger o Adjustable Regulated Charging Up to 1.5A DC o...