BQ4285S-SB2TR

The BQ4285S-SB2TR from Texas Instruments is a low-power microprocessor peripheral that provides a time-of-day clock and a 100-year calendar with alarm features and battery operation. It is functionally compatible with the DS1285 and closely matches the MC146818A pin configuration.

Key features include 114 bytes of general non-volatile storage, automatic backup and write-protect control to external SRAM, and a fast 160 ns cycle time. The calendar includes automatic leap-year adjustment, and the time of day can be displayed in 12- or 24-hour format with optional daylight saving adjustment. It supports BCD or binary format for clock and calendar data and offers a programmable square wave output.

This IC provides three individually maskable interrupt event flags with periodic rates from 122 μs to 500 ms, time-of-day alarms, and an end-of-clock update cycle. The device operates over a temperature range of 0°C to 70°C and requires a voltage supply between 2.5V and 4V.

The BQ4285S-SB2TR is available in a 24-pin SOIC package, suitable for surface mounting. It utilizes a parallel interface for communication. The device write-protects clock, calendar, and storage registers during power failure, maintaining data with a backup battery.