DS1305N

Real Time Clock Overview

The DS1305N is a serial alarm real-time clock (RTC) manufactured by Analog Devices Inc./Maxim Integrated. It provides a full binary coded decimal (BCD) clock/calendar tracking seconds, minutes, hours, date, month, day of week, and year with leap-year compensation valid to 2100. The device includes 96 bytes of battery-backed NV RAM for data storage. It supports SPI Modes 1 and 3 or standard 3-wire interfaces via the SERMODE pin. Operating voltage ranges from 2.0V to 5.5V on primary and backup supplies. The industrial temperature grade (-40°C to +85°C) is housed in a 16-pin DIP package.

Real Time Clock Feature Summary

• Dual power supply pins (VCC1, VCC2) and VBAT input support non-rechargeable batteries or rechargeable sources like super capacitors.
• Programmable trickle charger allows charging backup energy sources using selectable resistor and diode configurations.
• Two independent time-of-day alarms with programmable mask bits for seconds, minutes, hours, and days.
• Interface logic power supply (VCCIF) enables compatibility with 3V logic systems in mixed-voltage environments.

Real Time Clock Applications

• Industrial systems requiring precise timekeeping across wide temperature ranges.
• Data logging devices utilizing the 96-byte NV RAM for persistent storage.
• Microcontroller-based embedded systems needing interrupt-driven alarm events.
• Battery-operated equipment requiring low standby current consumption.

Real Time Clock Procurement Notes

Verify the specific suffix 'N' confirms the industrial temperature range (-40°C to +85°C) and 16-pin DIP packaging. Confirm RoHS compliance status as the datasheet indicates '+' denotes lead-free/RoHS-compliant packages, while the base model may differ. Ensure interface logic voltage requirements match the VCCIF specification for the target system.

Real Time Clock Selection Notes

Select this component when both SPI and 3-wire interface flexibility are required via the SERMODE pin. Choose the industrial grade variant for applications operating below 0°C. Ensure the design accommodates the separate VCC1, VCC2, and VBAT pins for proper power management and backup switching logic.

Real Time Clock Part Context

The DS1305N belongs to the DS1305 family of serial alarm RTCs. The 'N' suffix specifically identifies the industrial temperature range version (-40°C to +85°C) packaged in a 16-pin DIP. Other variants include the commercial grade DS1305 (0°C to +70°C) and surface mount options like the DS1305E/TSSOP.

Real Time Clock Replacement Considerations

Public confirmed substitute part numbers: None listed in source material.