DS1543W-120

Real Time Clock Overview

The DS1543W-120 is a 64k non-volatile static RAM integrated with a real-time clock/calendar, watchdog timer, and alarm. Operating at 3.3V with 120 ns access time, it features a parallel interface and 28-pin DIP package. The device includes an internal lithium battery for data retention exceeding 10 years without power. It provides BCD-coded timekeeping up to the year 2100 with automatic leap year compensation. Key functions include programmable alarms, interrupt generation, and power-fail write protection.

Real Time Clock Feature Summary

• Integrated 64k NV SRAM with RTC, crystal, and lithium battery in one package
• Parallel interface with 120 ns access time for 3.3V operation
• Automatic leap year compensation valid through 2100
• Programmable watchdog timer and alarm with interrupt output

Real Time Clock Applications

• Industrial control systems requiring precise timekeeping
• Data logging equipment needing non-volatile storage
• Embedded systems with watchdog requirements
• Battery-backed memory applications

Real Time Clock Procurement Notes

Verify component authenticity through authorized channels. Confirm package integrity and pin alignment before installation. Check datasheet specifications for voltage and timing requirements. Ensure proper handling of the lithium battery source during soldering processes.

Real Time Clock Selection Notes

Select this model for 3.3V systems requiring 120 ns access speed. Compare with 70 ns or 100 ns variants if faster performance is needed. Consider the industrial temperature range (-40°C to +85°C) for harsh environments. Verify compatibility with existing parallel bus architectures.

Real Time Clock Part Context

Part of the DS1543 family offering integrated RTC and NV SRAM solutions. Available in 5V (DS1543) and 3.3V (DS1543W) versions. Offers different access speeds including 70 ns, 100 ns, 120 ns, and 150 ns options. Designed for applications combining timekeeping with persistent data storage.

Real Time Clock Replacement Considerations

Direct substitutes within the DS1543 family include DS1543W-150 (150 ns access) and DS1543W-70 (70 ns access). For 5V systems, consider the DS1543 series. Verify pinout compatibility and electrical characteristics before substitution.

Real Time Clock FAQ

How is the lithium battery activated?

The lithium energy source is electrically disconnected upon shipment. It activates automatically when VCC is first applied above the power-fail threshold.

What is the data retention period?

The device guarantees over 10 years of data retention at 25°C with the oscillator running in the absence of VCC.

Can the alarm function wake the system from battery backup?

Yes, the alarm can be programmed to activate the IRQ/FT output while in battery-backed mode to serve as a system wake-up signal.