PCF2127AT/1,518

Real Time Clock Overview

The PCF2127AT/1,518 is a CMOS Real Time Clock (RTC) and calendar featuring an integrated Temperature Compensated Crystal Oscillator (TCXO) and a 32.768 kHz quartz crystal. It provides high accuracy with typical precision of ±3 ppm from -15°C to +60°C. The device includes 512 bytes of battery-backed static RAM and supports selectable I²C or SPI interfaces. Operating voltage ranges from 1.2 V to 4.2 V, with a typical supply current of 0.65 µA at 3.0 V. It offers timestamping, watchdog, alarm, and countdown timer functions within a 20-lead SO package.

Real Time Clock Feature Summary

• Integrated TCXO with 32.768 kHz quartz crystal for ±3 ppm accuracy (-15°C to +60°C)
• Selectable 400 kHz Fast-mode I²C bus or 6.5 Mbit/s 3-line SPI bus
• 512-byte general purpose static RAM with battery backup
• Timestamp function with interrupt capability and tamper detection on multilevel input pin

Real Time Clock Applications

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

Real Time Clock Procurement Notes

Verify the ordering suffix /1,518 corresponds to IC revision 1 in tape and reel delivery form (12NC 935290953518). Note that this part is not recommended for new designs; the replacement part is PCF2127AT/2. Confirm package type is SO20 (SOT163-1) during procurement.

Real Time Clock Selection Notes

Select PCF2127AT/1,518 when IC revision 1 is required for legacy compatibility. Ensure interface selection logic (IFS pin) matches the chosen bus protocol. Verify operating temperature requirements fall within the specified range for the desired accuracy specification.

Real Time Clock Part Context

This component belongs to the PCF2127 family of RTCs with integrated TCXO. The /1,518 suffix indicates specific manufacturing revision and packaging format. It serves as a predecessor to the PCF2127AT/2 variant, maintaining functional equivalence while differing in internal revision levels.

Real Time Clock Replacement Considerations

The official replacement part is PCF2127AT/2. Verify pinout compatibility and register mapping consistency between revision 1 and revision 2 before substitution.