PCF2129T/2,518

Real Time Clock Overview

The PCF2129T/2,518 is a CMOS Real Time Clock (RTC) and calendar IC from NXP Semiconductors. It features an integrated Temperature Compensated Crystal Oscillator (TCXO) with a 32.768 kHz quartz crystal, optimized for high accuracy and low power consumption. The device supports selectable I²C or SPI interfaces and operates within a voltage range of 1.8 V to 4.2 V. It provides complete calendar functions including leap year correction, programmable alarms, watchdog timers, and timestamp capabilities. The typical supply current is 0.70 µA at 3.3 V, and it operates across a temperature range of -40 °C to +85 °C.

Real Time Clock Feature Summary

• Integrated TCXO with ±3 ppm accuracy (-30 °C to +80 °C)
• Selectable I²C (400 kHz Fast-mode) or SPI (6.5 Mbit/s) interface
• Programmable alarm, watchdog timer, and timestamp functions
• Battery backup switch-over circuitry with battery low detection

Real Time Clock Applications

• Electronic metering for electricity, water, and gas
• GPS equipment to reduce time to first fix
• Precision timekeeping applications
• Products requiring long automated unattended operation

Real Time Clock Procurement Notes

Verify the package type matches the specific suffix; PCF2129T uses SO16 while PCF2129AT uses SO20. Confirm the ordering suffix /2,518 indicates reel packing. Ensure the operating temperature range requirements align with the industrial grade specifications provided in the datasheet.

Real Time Clock Selection Notes

Select this component when high timing accuracy without external crystals is required. The integrated TCXO eliminates layout sensitivity issues associated with discrete crystals. Choose between I²C and SPI based on system bus availability. Consider the battery backup features if continuous timekeeping during power loss is necessary.

Real Time Clock Part Context

The PCF2129 series includes variants like PCF2129AT and PCF2129T. The 'T' variant denotes the SO16 package, while 'AT' denotes the SO20 package. Both share similar electrical characteristics but differ in pin count and physical dimensions. The PCF2129T/2,518 specifically refers to the tape and reel version of the SO16 package.

Real Time Clock Replacement Considerations

Direct replacements should be sought from the same PCF2129 family. Verify package compatibility (SO16 vs SO20) and interface selection (I²C/SPI). Check if the alternative part offers similar accuracy and power management features.