BQ3285E Texas instruments

BQ3285E

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BQ3285E

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Описание

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.

Direct clock/calendar replacement for IBM® AT-compatible computers and other applications
Functionally compatible with the DS1285
- Closely matches MC146818A pin configuration
2.7–3.6V operation (bq3285L);
4.5–5.5V operation (bq3285E)
242 bytes of general nonvolatile storage
32.768kHz output for power management
System wake-up capability—alarm interrupt output active in battery-backup mode
Less than 0.5µA load under battery operation
Selectable Intel or Motorola bus timing
14 bytes for clock/calendar and control
BCD or binary format for clock and calendar data
Calendar in day of the week, day of the month, months, and years, with automatic leap-year adjustment
Time of day in seconds, minutes, and hours
- 12- or 24-hour format
- Optional daylight saving adjustment
Programmable square wave output
Three individually maskable interrupt event flags:
- Periodic rates from 122us to 500ms
- Time-of-day alarm once per second to once per day
- End-of-clock update cycle
24-pin plastic DIP, SOIC, or SSOP

Function	Real-time clock
Iq (typ) (mA)	0.0005
Features	0.242-kB memory density, 14 RTC bytes, Multiplexed bus interface, RAM clear function
Rating	Catalog
Operating temperature range (°C)	0 to 70
Supply voltage (max) (V)	7
Supply voltage (min) (V)	-0.3