DS12C887A

Real Time Clock Overview

The DS12C887A is a Real-Time Clock (RTC) and calendar integrated circuit manufactured by Analog Devices Inc. / Maxim Integrated. It operates within a supply voltage range of 4.5V to 5.5V and features a multiplexed parallel interface. The device includes an internal lithium battery backup system, ensuring timekeeping continuity during power failures. Key specifications include 113 bytes of non-volatile static RAM, support for both 12-hour and 24-hour time formats, and automatic leap year compensation through the year 2099. It is housed in a 24-pin EDIP module package designed for through-hole mounting.

Real Time Clock Feature Summary

• Integrated Battery Backup: Internal lithium battery maintains time and data without external components.
• Multiplexed Parallel Interface: Supports Intel and Motorola bus timing modes for direct microprocessor connection.
• Calendar and Timekeeping: Counts seconds, minutes, hours, date, day, month, and year with leap year correction.
• Non-Volatile Memory: Provides 113 bytes of battery-backed static RAM for user data storage.

Real Time Clock Applications

• Embedded systems requiring precise timestamping
• Utility meters and smart grid devices
• Network hubs, bridges, and routers
• Security systems and access control

Real Time Clock Procurement Notes

Verify the specific manufacturer designation, as Analog Devices and Maxim Integrated are listed. Confirm the package type is the 24-EDIP module containing the integrated crystal and battery. Ensure the design supports the required parallel bus timing mode compatible with the target microcontroller architecture.

Real Time Clock Selection Notes

Select this component when a parallel interface is preferred over serial protocols like I2C or SPI. The DS12C887A is suitable for applications needing high-speed RAM access and robust timekeeping without external oscillators. Verify that the system voltage remains within the 4.5V to 5.5V range for proper operation.

Real Time Clock Part Context

This part belongs to the DS12C887 family, which serves as a drop-in replacement for legacy IBM AT computer clock/calendar chips. The 'A' suffix typically denotes specific manufacturing revisions or compliance updates within the series, maintaining functional compatibility with earlier models like the DS12887 while adding century byte support at address 32h.

Real Time Clock Replacement Considerations

Direct pin-compatible replacements include the DS12C887 and DS12887. For modern designs requiring smaller footprints, consider transitioning to serial RTCs such as the DS1307 or DS3231, though these require significant schematic and software modifications due to interface differences.