DS1344E-33+

Real Time Clock Overview

The DS1344E-33+ is a low-current real-time clock (RTC) IC manufactured by Analog Devices Inc./Maxim Integrated. It provides timekeeping and calendar functions including seconds, minutes, hours, day, date, month, and year with leap year compensation valid through 2099. The device supports SPI or 3-wire serial interfaces and includes two programmable alarms with interrupt outputs. It features 96 bytes of battery-backed NV RAM. Electrical specifications include an operating voltage range of 3.0V to 5.5V for VCC and 1.3V to 5.5V for VBAT. Typical standby current is 250nA, with active supply currents ranging from 120µA to 160µA depending on voltage. It operates in the -40°C to +85°C temperature range and is housed in a 20-pin TSSOP package.

Real Time Clock Feature Summary

• Integrated capacitive loading for 12.5pF crystals
• Two programmable time-of-day alarms with dual interrupt outputs
• 96-byte battery-backed non-volatile RAM
• Supports SPI Mode 1/3 and standard 3-wire interface

Real Time Clock Applications

• Medical devices
• Handheld devices
• Telematics systems
• Embedded timestamping

Real Time Clock Procurement Notes

Verify the specific suffix 'E' indicates the extended industrial temperature grade (-40°C to +85°C) and '33' denotes the 3.3V nominal operating voltage. Confirm the package type is 20-TSSOP. Ensure compatibility with 12.5pF load capacitance crystals as specified for the DS1344 variant. Check RoHS compliance status if required by local regulations.

Real Time Clock Selection Notes

Select the DS1344E-33+ over the DS1343 variant when the application requires integrated capacitive loading for 12.5pF crystals rather than 6pF. Ensure the system power supply remains within the 3.0V to 5.5V range for VCC. Verify that the microcontroller supports either SPI or 3-wire serial communication protocols. Consider the 96-byte NVRAM capacity for data storage requirements.

Real Time Clock Part Context

The DS1344E-33+ belongs to the DS1343/DS1344 family of low-current RTCs. It shares core functionality with the DS1343 but differs in internal oscillator loading capacitance (12.5pF vs 6pF). The 'E' suffix typically signifies the extended temperature range version, while '33' specifies the 3.3V operating voltage tier. This part is designed for applications requiring long battery life and precise timekeeping.

Real Time Clock Replacement Considerations

The DS1343E-33+ is a functional substitute if the design accommodates 6pF crystal load capacitance instead of 12.5pF. Other DS1344 variants with different packages (e.g., TDFN) may require PCB layout changes. Verify pinout compatibility and software register mapping before substitution.