BQ4802Y - Y2K-Compliant Parallel RTC with CPU Supervisor and External NVSRAM Control, 5V Vcc

The bq4802Y/bq4802LY real-time clock is a low-power microprocessor peripheral that integrates a time-of-day clock, a century-based calendar, and a CPU supervisor, with package options including a 28-pin SOIC, TSSOP, or SNAPHAT that requires the bq48SH-28x6 to complete the two-piece module. The bq4802Y/ bq4802LY is ideal for fax machines, copiers, industrial control systems, point-of-sale terminals, data loggers, and computers.

The bq4802Y/bq4802LY provides direct connections for a 32.768-kHz quartz crystal and a 3-V backup battery. Through the use of the conditional chip enable output (CE\_OUT) and battery voltage output (V_OUT) pins, the bq4802Y/bq4802LY can write-protect and make non- volatile external SRAMs. The backup cell powers the real-time clock and maintains SRAM information the absence of system voltage. The crystal and battery are contained within the modules for a more integrated solution.

The bq4802Y/bq4802LY contains a temperature-compensated reference and comparator circuit that monitors the status of its voltage supply. When the bq4802Y/bq4802LY detects an out-of-tolerance condition, it generates an interrupt warning and subsequently a microprocessor reset. The reset stays active for 200 ms after V_CC rises within tolerance, to allow for power supply and processor stabilization. The reset function also allows for an external push-button override.

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• Real-Time Clock Counts Seconds Through Centuries in BCD Format
  • bq4802Y: 5-V Operation
  • bq4802LY: 3.3-V Operation
• On-Chip Battery-Backup Switchover Circuit With Nonvolatile Control for External SRAM
• Less Than 500 nA of Clock Operation Current in Backup Mode
• Microprocessor Reset With Push-Button Override
• Independent Watchdog Timer With Programmable Time-Out Period
• Power-Fail Interrupt Warning
• Programmable Clock Alarm Interrupt Active in Battery-Backup Mode
• Programmable Periodic Interrupt
• Battery-Low Warning
• 28-pin SOIC, TSSOP, and SNAPHAT Package Options
• APPLICATIONS
  • Telecommunications Base Stations
  • Servers
  • Handheld Data Collection Equipment
  • Medical Equipment
  • Handheld Instrumentation
  • Test Equipment