We have a #PCF2129 RTC connected to an mcu via i2c. Its been observed that after a certain amount of time and multiple power on/off operations, the oscillator in the RTC is getting reset(last bit of the Seconds register was found to be set) causing reset of the RTC itself and thus loss of time. The datasheet says that issue is more likely to be come due loss of power to RTC. I am adding the circuitry of the RTC for reference. Is there anything that we are missing which might lead to oscillator reset. Although I noticed that SDI should be connected to Vss when using i2c, I don't see how that will cause the resetting of the oscillator.
Also there is an OTPR bit in CLKOUT_ctl register. What is the purpose of that register and do I need to perform that refresh every-time I power on the system?