ACPI Compliant RTC IC W 242x8 NVSRAM Alarm Wake-up Dedicated 32kHz Output 3V Op On L Version

The CMOS bq3285ED/LD is Real-Time Clock RTC a low-power Microprocessor peripheral providing a time-of-day Clock and 100-year calendar with alarm features and battery operation. The architecture is based on the BQ3285 7 RTC with added features: low-voltage operation, 32.768kHz output, 128 additional bytes of CMOS, and a day-of-month alarm to be compliant with the ACPI RTC specification.
A 32.768kHz output is available for sustaining power-management activities. The bq3285ED/LD 32kHz output is always on whenever VCC is valid. In VCC standby mode, the 32kHz is active, and the BQ3285LD typically draws 100uA while the bq3285ED typically draws 300uA. Wake-up capability is provided by an alarm interrupt, which is active in battery-backup mode. In battery-backup mode, current drain is less than 550nA.
The bq3285ED/LD write-protects the Clock calendar, and storage Registers during power failure. A backup battery then maintains data and operates the Clock and calendar.
The bq3285ED/LD is a fully compatible Real-Time Clock for IBM AT-compatible computers and other applications. The only external components are a 32.768kHz crystal and a backup battery.
The bq3285ED is intended for use in 5V systems. The BQ3285LD is intended for use in 3V systems; the BQ3285LD however, may also operate at 5V and then go into a 3V power-down state, write-protecting as if in a 3V system.
By Texas Instruments