DS1315-5

Real Time Clock Overview

The DS1315 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 to 2100. The device operates on +3.3V or +5V supplies with a full ±10% operating range. In the absence of power, an external battery maintains timekeeping and powers a connected CMOS static RAM via the VCCO output. Communication uses a serial bit stream pattern recognition sequence, eliminating the need for dedicated address space.

Real Time Clock Feature Summary

• Phantom Time Chip interface using 64-bit pattern recognition without address space requirements
• Nonvolatile controller supports redundant battery attachment for high-reliability applications
• Automatic leap year correction valid up to the year 2100
• Supports both 12-hour (AM/PM) and 24-hour time formats

Real Time Clock Applications

• Systems requiring nonvolatile SRAM backup with integrated timekeeping
• High-reliability industrial equipment with redundant battery configurations
• Personal computer storage card interfaces (PCMCIA)
• Data logging devices requiring precise calendar and clock tracking

Real Time Clock Procurement Notes

Verify the specific voltage variant required, as the DS1315 family includes distinct -33+ (3.3V) and -5+ (5V) versions. Confirm package type availability, such as 16-pin PDIP, 16-pin SO, or 20-pin TSSOP, against the design footprint. Check for lead-free (+) suffix compliance if RoHS standards are mandatory. Note that industrial temperature variants carry an 'N' designation in the part number.

Real Time Clock Selection Notes

Select the appropriate supply voltage version based on the system's main power rail (+3.3V or +5V). Ensure the crystal load capacitance matches the specified 6pF requirement for accurate timing. For designs using external CMOS RAM, connect the ROM/RAM pin to ground; for ROM-only applications, connect it to VCCO. Verify that the operating temperature range meets the application environment, choosing between commercial (0°C to +70°C) and industrial (-40°C to +85°C) grades.

Real Time Clock Part Context

The DS1315 belongs to the Maxim Integrated Phantom Time Chip family, designed to simplify nonvolatile memory integration by embedding RTC functionality directly into the memory controller logic. This architecture reduces component count compared to separate RTC and memory controller solutions. The device is manufactured by Analog Devices / Maxim Integrated.

Real Time Clock Replacement Considerations

Direct replacements must match the specific voltage rating and package style. Valid equivalents within the same series include DS1315-33+, DS1315N-5+, DS1315S-5+, and DS1315EN-5+. Ensure the substitute supports the same 64-bit phantom communication protocol and provides identical VCCO switching characteristics for battery backup.