2368423_en-US

[#1]

Time Drift in PCF85063TP/1Z RTC

We are using the PCF85063TP/1Z RTC in our temperature logger product for maintaining time stamps during temperature data logging. During testing, we observed time drift issues across multiple boards, where each board shows a different amount of drift over time.

In our current hardware design, we are using a 12.5 pF load capacitance crystal. Based on this, we updated the RTC register setting by configuring the CAP_SEL bit to ‘1’ to match the crystal load capacitance requirement.

After making this configuration change, we are still observing approximately 2 seconds of drift in real-time operation.

We would like to understand:

• Whether this level of drift is expected for the PCF85063TP/1Z.
• If there are any recommended register configurations or calibration methods to improve RTC accuracy.
• Whether PCB layout, crystal selection, or other hardware considerations could contribute to the observed variation between boards.

Kindly provide your recommendations and guidance for improving RTC timing accuracy in this application.

Re: Time Drift in PCF85063TP/1Z RTC

Hello,

Please see application note AN11247 Improved timekeeping accuracy with PCF85063, PCF8523 and PCF2123 using an external temperatu...

Hope this helps!