DS1315N-33

Real Time Clock Overview

The DS1315N-33 is a CMOS Phantom Time Chip combining a real-time clock and nonvolatile memory controller. It tracks hundredths of seconds, seconds, minutes, hours, day, date, month, and year with automatic leap year correction valid through 2100. Operating at +3.3V (3.0V to 3.6V range), it features an industrial temperature rating of -40°C to +85°C. The device uses a serial interface requiring a 64-bit pattern recognition sequence for access, eliminating the need for dedicated address space. It supports battery backup for external SRAM via redundant BAT1/BAT2 inputs and provides power-fail detection with write protection.

Real Time Clock Feature Summary

• Phantom Time Chip architecture using 64-bit serial pattern recognition for RTC access without address space allocation
• Integrated nonvolatile controller for battery-backed CMOS SRAM with redundant dual-battery support
• Automatic leap year correction valid up to the year 2100
• Industrial temperature range (-40°C to +85°C) with ±10% VCC operating tolerance

Real Time Clock Applications

• Systems requiring precise timekeeping with nonvolatile RAM backup
• High-reliability applications utilizing redundant battery attachment
• Embedded controllers interfacing with external SRAM or ROM

Real Time Clock Procurement Notes

Verify component authenticity as the DS1315N-33 may be discontinued or superseded by newer revisions. Confirm that the specific package variant matches the required PCB footprint, as the datasheet lists PDIP, SO, and TSSOP options. Ensure the design accounts for the specific 64-bit access protocol rather than standard I2C or SPI interfaces.

Real Time Clock Selection Notes

Select this component when a dedicated address bus is unavailable for RTC communication. The DS1315N-33 requires a 32.768kHz crystal with a 6pF load capacitance. Designers must implement the 64-bit write cycle sequence on the D pin to enable time register access. Verify that the system voltage remains within the 3.0V to 3.6V range for optimal standby current performance.

Real Time Clock Part Context

The DS1315N-33 belongs to the Maxim Integrated DS1315 family of Phantom Time Chips. The 'N' suffix denotes the industrial temperature grade (-40°C to +85°C), while '33' indicates the +3.3V supply version. This part integrates timekeeping and memory control functions, distinguishing it from standalone RTCs that lack nonvolatile RAM management capabilities.

Real Time Clock Replacement Considerations

Direct pin-compatible replacements are not explicitly listed in the provided documentation. Review the DS1315E series for commercial temperature variants or other Maxim RTCs if the phantom interface is acceptable. Verify functional equivalence regarding the 64-bit access pattern and battery switching logic before substitution.