DS1501W

Real Time Clock Overview

The DS1501W is a Y2K-compliant real-time clock/calendar IC with a parallel interface. It operates at +3.3V (nominal range 3.0V to 3.6V) and includes a watchdog timer, power-on reset, battery monitors, and 256 bytes of NV SRAM. Timekeeping registers store century, year, month, date, day, hours, minutes, and seconds in 24-hour BCD format with automatic leap-year compensation valid through 2100. The device supports an auxiliary battery input for kickstart and square-wave functions.

Real Time Clock Feature Summary

• BCD-coded time/date with automatic leap-year correction valid up to the year 2100
• Integrated 256-byte battery-backed NV SRAM
• Programmable watchdog timer and RTC alarm with interrupt output
• +3.3V operation with precision power-on reset and battery voltage-level indicators

Real Time Clock Applications

• Remote Systems
• Battery-Backed Systems
• Telecom Switches
• Office Equipment
• Consumer Electronics

Real Time Clock Procurement Notes

Verify the specific suffix against the datasheet ordering table to confirm voltage and temperature ratings. The 'W' designation indicates +3.3V operation within the 0°C to +70°C range. Confirm lead-free status via the '+' symbol on the top mark or RoHS documentation. Check for available errata revisions before finalizing component selection.

Real Time Clock Selection Notes

Select this part when a +3.3V supply is required alongside a parallel interface. Ensure the external crystal matches the specified load capacitance of either 6pF or 12.5pF by configuring the CS bit. Verify that the system design accommodates the open-drain outputs for IRQ, PWR, and RST pins, which require pull-up resistors.

Real Time Clock Part Context

The DS1501W belongs to the DS1501/DS1511 family of Y2K-compliant real-time clocks. While the DS1511 is a standalone encapsulated DIP module with an embedded battery and crystal, the DS1501 is a chip-only variant requiring external components. The W suffix specifically denotes the +3.3V operating voltage version.

Real Time Clock Replacement Considerations

The DS1501WE+ serves as the commercial temperature (+0°C to +70°C) equivalent. For industrial temperature requirements (-40°C to +85°C), the DS1501WEN+ is the appropriate alternative within the same package.