BQ4847YMT

Overview

The BQ4847YMT is a discontinued Real-Time Clock (RTC) module from Texas Instruments, housed in a 28-pin T-type DIP package. It integrates a time-of-day clock, a 100-year calendar, a CPU supervisor, an internal battery, and a crystal. The device counts seconds through years in BCD format with ±1 minute per month accuracy at room temperature. It features a 130mAh internal battery capacity and less than 500nA operation current in backup mode. The module includes a microprocessor reset valid to VSS, an independent watchdog timer, power-fail interrupt warning, programmable clock alarm and periodic interrupts, and a battery-low warning.

Feature Summary

• Integrated 130mAh battery and quartz crystal within a 28-pin DIP module
• On-chip battery-backup switchover circuit with nonvolatile control for external SRAM via CEOUT and VOUT pins
• Microprocessor reset valid to VSS with 200ms stabilization delay after VCC rise
• Independent watchdog timer with programmable time-out period and power-fail interrupt warning

Applications

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

Procurement Notes

The BQ4847YMT is classified as Obsolete by Texas Instruments, indicating that production has been discontinued. Buyers should verify the availability of remaining stock or consider lifetime-buy options if applicable. Designers are advised not to use this component in new designs due to its obsolete status. Sourcing may be limited to distributor surplus inventory.

Selection Notes

The 'Y' suffix denotes a voltage tolerance of 10%, whereas the standard BQ4847MT offers 5% tolerance. This RTC module is functionally equivalent to the BQ4845 but with internally connected battery and crystal pins. It is suitable for applications requiring low-power timekeeping and CPU supervision with external SRAM retention capabilities during power failures.

Part Context

The bq4847/bq4847Y series serves as a low-power microprocessor peripheral combining RTC and CPU supervisor functions. It is designed to maintain system time and data integrity in external SRAM during power outages using its internal backup cell. The module simplifies design by integrating components typically found on separate boards.

Replacement Considerations

Texas Instruments explicitly states that this part is Not Recommended For New Designs. No direct public substitute part numbers are listed in the provided documentation. Designers should evaluate newer RTC modules with integrated supervisors or discrete solutions.