| Iq (Typ) (uA) | 0.5 |
| Features | RAM clear function, Multiplexed bus interface, 14 RTC bytes, 0.242-kB memory density |
| Rating | Catalog |
| Operating temperature range (C) | 0 to 70 |
| Supply voltage (Max) (V) | 7 |
| Supply voltage (Min) (V) | -0.3 |
- 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
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.
