DS1556P-70

Real Time Clock Overview

The DS1556P-70 is a 1M nonvolatile, Y2K-compliant timekeeping RAM device integrating an RTC, 128k x 8 SRAM, crystal, and lithium battery. It features a parallel interface with 70 ns access time and operates on a single 5V supply. The component includes programmable watchdog timer and alarm functions, automatic leap-year compensation, and power-fail write protection. Data retention exceeds 10 years in the absence of power. It utilizes a 34-pin PowerCap module package.

Real Time Clock Feature Summary

• Integrated 128k x 8 Nonvolatile SRAM with Real-Time Clock
• Y2K-Compliant BCD Calendar with Automatic Leap-Year Compensation
• Programmable Watchdog Timer and Alarm Functions
• Power-Fail Write Protection and Precision Power-On Reset
• 34-Pin PowerCap Module Package for Surface Mount Assembly

Real Time Clock Applications

• Industrial control systems requiring persistent timekeeping
• Portable electronic devices with battery backup requirements
• Data logging equipment needing nonvolatile storage
• Embedded systems with watchdog timer dependencies

Real Time Clock Procurement Notes

Verify the specific ordering suffix to confirm temperature range and lead-free status. The base model DS1556P-70 typically denotes the commercial grade (0°C to +70°C). Industrial variants require the IND suffix. Confirm RoHS compliance through the '+' designation. Ensure the separate PowerCap module (DS9034PCX) is ordered if using the PowerCap package variant.

Real Time Clock Selection Notes

Select the DS1556P-70 for applications requiring 128k bytes of nonvolatile memory alongside precise timekeeping. Verify that the system voltage aligns with the 5V nominal requirement. Consider the industrial temperature range (-40°C to +85°C) if operating conditions exceed commercial limits. Ensure the PCB layout accommodates the 34-pin PowerCap footprint and allows for separate mounting of the battery module post-reflow.

Real Time Clock Part Context

The DS1556 belongs to the Maxim Integrated DS155x family of real-time clocks with integrated nonvolatile RAM. This series provides a consolidated solution for timekeeping and data storage, eliminating the need for external batteries and crystals. The P suffix indicates the PowerCap module package, which separates the sensitive lithium cell from the soldering process.

Real Time Clock Replacement Considerations

Direct replacements within the same package and pinout include the DS1556P-70IND+ for industrial temperature ranges. Other family members like the DS1557 or DS1558 offer different memory sizes or additional features but may require schematic modifications. Verify compatibility with existing firmware before substitution.