DS1553P-70+

Real Time Clock Overview

The DS1553P-70+ is a Year-2000-compliant real-time clock/calendar with 64kB nonvolatile static RAM. It integrates the RTC, crystal, lithium energy source, and power-fail control circuit in a 34-pin PowerCap module. The device uses a byte-wide parallel interface where RTC registers reside in the top 16 locations of the SRAM. It supports BCD-coded timekeeping up to the year 2100 with automatic leap year compensation. Key features include a programmable watchdog timer, RTC alarm, precision power-on reset, and battery voltage monitoring. Data retention exceeds 10 years without power.

Real Time Clock Feature Summary

• Integrated 64kB NV SRAM with RTC registers mapped to the top 16 memory locations
• Built-in lithium energy source and crystal for over 10 years of data retention
• Programmable watchdog timer and RTC alarm with interrupt output
• Precision power-on reset and power-fail write protection

Real Time Clock Applications

• Systems requiring precise timekeeping and nonvolatile data storage
• Applications needing CPU watchdog functionality via IRQ/RST outputs
• Battery-backed systems requiring automatic power switchover

Real Time Clock Procurement Notes

Verify that the separate DS9034PCX PowerCap module is included or ordered separately, as it contains the required crystal and lithium battery. Confirm the specific voltage variant (5V or 3.3V) matches the system supply, as the base part number does not specify voltage. Check for lead-free compliance markings on the package top mark.

Real Time Clock Selection Notes

Select the appropriate voltage suffix based on the system supply: -85+/-100+ for 5V operation and -120+/-150+ for 3.3V operation. Ensure the 34-pin PowerCap package is suitable for the board layout, noting that the PowerCap module must be mounted after surface-mount soldering to protect the internal battery and crystal from reflow temperatures.

Real Time Clock Part Context

The DS1553P-70+ belongs to the DS1553 family of 64kB nonvolatile timekeeping RAM devices. It is functionally similar to other Maxim Integrated RTCs but distinguishes itself by integrating the backup power source and oscillator directly into the module architecture. The 'P' designation indicates the PowerCap package style, which requires an external connector module for the energy source.

Real Time Clock Replacement Considerations

Direct replacements include other DS1553 variants with different voltage ratings (e.g., DS1553P-85+, DS1553P-100+) or package types (e.g., DS1553-85+). Verify pin compatibility and voltage levels when substituting.