BQ4845YS-A4TR

Overview

The BQ4845YS-A4TR is a parallel real-time clock (RTC) with CPU supervisor from Texas Instruments, housed in a 28-pin SOIC package. It integrates a time-of-day clock and a 100-year calendar using BCD format. The device features on-chip battery-backup switchover for external SRAM nonvolatile control, drawing less than 500nA in backup mode. It includes a microprocessor reset valid to VSS, an independent watchdog timer, power-fail interrupt warning, programmable clock alarm, periodic interrupt, and battery-low warning.

Feature Summary

• Parallel RTC with 16-byte register map for time, date, and control
• Battery-backed external SRAM control via CEOUT and VOUT pins
• Watchdog timer with programmable timeout periods
• Power-fail detection with automatic write-protection

Applications

• Fax machines
• Copiers
• Industrial control systems
• Point-of-sale terminals
• Data loggers

Procurement Notes

Verify the specific suffix 'A4TR' against official TI documentation to confirm tape-and-reel packaging and any distinct electrical tolerances compared to standard variants. Ensure the source document explicitly defines this suffix before procurement.

Selection Notes

Select this component when a parallel interface is required for direct connection to standard SRAM buses. Verify that the 28-pin SOIC footprint fits the design constraints and that the 5V supply voltage range aligns with the system architecture.

Part Context

This part belongs to the bq4845 family of low-power microprocessor peripherals. It combines RTC functionality with CPU supervision, distinguishing it from standalone clock chips by providing hardware-level reset and memory protection capabilities.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided datasheet or local source material.