BQ4285E是TI公司的一款无产品，BQ4285E是RTC IC，具有 114x8 NVSRAM 和 NVSRAM 控制、针对 L 版本发出警报唤醒 3V 操作，本页介绍了BQ4285E的产品说明、应用、特性等，并给出了与BQ4285E相关的TI元器件型号供参考。
BQ4285E - RTC IC，具有 114x8 NVSRAM 和 NVSRAM 控制、针对 L 版本发出警报唤醒 3V 操作 - 无 - 实时时钟 - TI公司（Texas Instruments，德州仪器）
The CMOS bq4285E/L is a low-power microprocessor peripheral providing a time-of-day clock and 100-year calendar with alarm features and battery operation. Other features include three maskable interrupt sources, square wave output, and 114 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 bq4285E/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 bq4285E/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.
The bq4285E/L integrates a battery-backup controller to make a standard CMOS SRAM nonvolatile during power-fail conditions. During power-fail, the bq4285E/L automatically write-protects the external SRAM and provides a VCC output sourced from the clock backup battery.
- Direct clock/calendar replacement for IBM® AT-compatible computers and other applications
- 114 bytes of general nonvolatile storage
- Enhanced features include:
- System wake-up capability—alarm interrupt output active in battery-backup mode
- 2.7–3.6V operation (bq4285L); 4.5–5.5V operation (bq4285E)
- 2kHz output for power management
- Automatic backup and write-protect control to external SRAM
- Functionally compatible with the DS1285
- Less than 0.5µA load under battery operation
- 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 out-put
- 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 or SOIC
