DS1306

Real Time Clock Overview

The DS1306 is a serial alarm real-time clock (RTC) providing binary coded decimal (BCD) timekeeping for seconds, minutes, hours, date, month, day of week, and year with leap-year compensation valid to 2100. It includes 96 bytes of battery-backed NV RAM and two programmable time-of-day alarms. The device supports Motorola SPI Modes 1 and 3 or standard 3-wire interfaces via the SERMODE pin. It operates from 2.0V to 5.5V on primary supplies (VCC1/VCC2) and features dual-power pins for backup switching. An interface logic supply (VCCIF) allows compatibility with 3V logic systems.

Real Time Clock Feature Summary

• Full BCD clock/calendar with automatic month-end adjustment and leap-year correction through 2100
• 96-byte battery-backed non-volatile RAM for data storage
• Dual programmable alarms with interrupt outputs (INT0/INT1)
• Supports SPI (Modes 1 & 3) and 3-wire serial interfaces
• Programmable trickle charger for supercapacitor or rechargeable battery backup

Real Time Clock Applications

• Systems requiring precise timekeeping with low power consumption
• Data logging applications utilizing the onboard NV RAM
• Mixed-supply environments interfacing with 3V logic via VCCIF
• Battery-operated devices using trickle charging for backup power

Real Time Clock Procurement Notes

Verify the specific package variant required, as the DS1306 family includes 16-pin DIP and 20-pin TSSOP options. Confirm temperature range specifications, noting that industrial grades (-40°C to +85°C) carry distinct ordering suffixes (e.g., 'N' or 'EN'). Ensure the selected part matches the desired serial interface configuration capabilities and backup power requirements.

Real Time Clock Selection Notes

Select the appropriate package based on board space constraints; the 20-pin TSSOP minimizes area while the 16-pin DIP suits through-hole designs. Choose between commercial (0°C to +70°C) and industrial (-40°C to +85°C) temperature ranges based on environmental conditions. Consider the VCCIF pin requirement if interfacing with 3V logic levels in mixed-supply systems.

Real Time Clock Part Context

The DS1306 belongs to the Maxim Integrated (now Analog Devices) DS1306 series of serial RTCs. It is functionally similar to other parts in the family but distinguished by its specific pinout and interface flexibility. Variants include the DS1306+ (commercial DIP), DS1306N (industrial DIP), and various TSSOP configurations. The '+' suffix indicates lead-free/RoHS compliance.

Real Time Clock Replacement Considerations

Direct substitutes within the same family include DS1306+, DS1306N, DS1306E, and their industrial equivalents. Verify pin compatibility when replacing DIP with TSSOP variants due to different pin counts (16 vs 20). Ensure the replacement supports the required serial mode (SPI or 3-wire) and temperature range.