BQ3287EMT

Overview

The BQ3287EMT is a CMOS real-time clock module designed for IBM AT-compatible systems. It integrates a 100-year calendar, time-of-day counter, and 242 bytes of nonvolatile RAM with an internal lithium cell and crystal. Operating at a 5V supply (4.5V–5.5V), it features a 160 ns cycle time and supports 12/24-hour formats with daylight saving adjustments. The device provides three maskable interrupts, a programmable square wave output, and a 32.768kHz output for power management. It ensures data retention for up to 10 years in battery-backup mode.

Feature Summary

• Integrated lithium cell and quartz crystal eliminate external components
• 242 bytes of general-purpose nonvolatile storage
• Three individually maskable interrupt sources: periodic, alarm, and end-of-clock update
• Automatic leap-year adjustment and daylight saving time support

Applications

• IBM AT-compatible computer systems
• Microprocessor peripheral timing applications
• Systems requiring battery-backed timekeeping and nonvolatile storage

Procurement Notes

Verify the obsolete status of the BQ3287EMT before procurement planning. Texas Instruments has discontinued production of this device. Designers should confirm availability through lifetime-buy periods or authorized distributors if existing inventory is required for maintenance purposes.

Selection Notes

Select the BQ3287EMT only for legacy system maintenance where functional compatibility with DS1287/DS1287A or MC146818A/B is required. The MT package denotes a 24-pin T-type module. Ensure the design accommodates the commercial temperature range of 0°C to +70°C and the specific 5V logic requirements.

Part Context

The BQ3287E is functionally equivalent to the bq3285E but with integrated battery and crystal pins. The 'MT' suffix indicates the 24-pin T-type module package. The 'EMT' designation specifically refers to the standard version without the RAM clear input found in the bq3287EA variant. This component serves as a direct replacement for older RTC modules in industrial and computing hardware.

Replacement Considerations

Texas Instruments lists the BQ3287EMT as obsolete. No direct active substitutes are identified in the provided documentation. Designers must evaluate legacy inventory or redesign using modern RTC solutions that meet current form-factor and interface constraints.