DS17885-3

Real Time Clock Overview

The DS17885-3 is a real-time clock (RTC) IC from the DS17x85 series, designed as a successor to the DS12885. It provides timekeeping for seconds through years with leap year compensation through 2099. The device features an 8KB battery-backed nonvolatile SRAM and a multiplexed byte-wide interface. It supports optional +3.0V or +5.0V operation, with power-fail detection automatically switching to backup supplies. Key functions include a time-of-day alarm, six maskable interrupts, a programmable square-wave output, and a 64-bit silicon serial number.

Real Time Clock Feature Summary

• Real-time clock/calendar with automatic leap year correction through 2099
• 8KB battery-backed NV SRAM for extended data storage
• Multiplexed address/data bus interface with +3.0V or +5.0V supply options
• Power-control circuitry enabling system wake-up via alarm or kickstart input
• 64-bit unique silicon serial number integrated into the device

Real Time Clock Applications

• Embedded systems requiring precise timekeeping
• Utility meters for billing and tracking
• Security systems needing event logging
• Network hubs, bridges, and routers

Real Time Clock Procurement Notes

Verify the specific package type required, as the DS17885 series is available in PDIP, SO, or TSOP formats. Confirm the voltage suffix matches the design (+3 for 2.7V–3.7V range, +5 for 4.5V–5.5V range). Check current availability status, as this component family may have limited stock or end-of-life implications depending on the distributor.

Real Time Clock Selection Notes

Select the DS17885-3 when 8KB of nonvolatile RAM is necessary, distinguishing it from the 2KB DS17285 and 4KB DS17485 variants. Ensure the system operates within the specified voltage range (2.7V–3.7V for the -3 suffix). Verify that the application can accommodate the multiplexed bus timing requirements and external crystal selection (6pF or 12.5pF load capacitance).

Real Time Clock Part Context

This component belongs to the Maxim Integrated DS17x85/DS17x87 family of real-time clocks. It serves as a direct upgrade path for legacy DS12885 designs, offering enhanced memory capacity and additional control features like kickstart functionality while maintaining pin compatibility with industry-standard interfaces.

Real Time Clock Replacement Considerations

The DS12885 is the primary predecessor. For direct replacement, ensure the new design accounts for the increased 8KB RAM size and verify that the multiplexed bus timing parameters are compatible with the host processor.