BQ3285E

具有 242x8 NVSRAM 警报唤醒功能的 RTC IC

The CMOS bq3285E/L is a low-power microprocessor peripheral providing a time-of-day clock and 100-year calendar with alarm features and battery operation. The bq3285L supports 3V systems. Other bq3285E/L features include three maskable interrupt sources, square-wave output, and 242 bytes of general nonvolatile storage.

A 32.768kHz output is available for sustaining power-management activities. Wake-up capability is provided by an alarm interrupt, which is active in battery-backup mode.

The bq3285E/L write-protects the clock, calendar, and storage registers during power failure. A backup battery then maintains data and operates the clock and calendar.

The bq3285E/L 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.

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Direct clock/calendar replacement for IBM® AT-compatible computers and other applications

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Functionally compatible with the DS1285

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Closely matches MC146818A pin configuration

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2.7–3.6V operation bq3285L;

4.5–5.5V operation bq3285E

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242 bytes of general nonvolatile storage

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32.768kHz output for power management

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System wake-up capability—alarm interrupt output active in battery-backup mode

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Less than 0.5µA load under battery operation

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Selectable Intel or Motorola bus timing

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14 bytes for clock/calendar and control

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BCD or binary format for clock and calendar data

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Calendar in day of the week, day of the month, months, and years, with automatic leap-year adjustment

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Time of day in seconds, minutes, and hours

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12- or 24-hour format

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Optional daylight saving adjustment

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Programmable square wave output

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Three individually maskable interrupt event flags:

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Periodic rates from 122us to 500ms

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Time-of-day alarm once per second to once per day

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End-of-clock update cycle

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24-pin plastic DIP, SOIC, or SSOP