PCF8523T/1 datasheet by NXP Semiconductors

PCF8523T/1 Frequently Asked Questions (FAQs)

• What is the recommended crystal oscillator frequency for the PCF8523T/1?
  The recommended crystal oscillator frequency for the PCF8523T/1 is 32.768 kHz, which is a standard frequency for real-time clocks.
• How do I ensure the PCF8523T/1 oscillator starts up correctly?
  To ensure the oscillator starts up correctly, make sure the crystal is properly connected, and the VDD pin is powered up before the VBAT pin. Also, ensure the oscillator enable bit (EOSC) is set to '1' in the control register.
• What is the purpose of the VBAT pin, and how should it be used?
  The VBAT pin is a backup power input that allows the PCF8523T/1 to maintain its clock and calendar information during power failures. It should be connected to a battery or a supercapacitor to provide backup power.
• How do I handle the PCF8523T/1's power-on reset (POR) and brown-out detection (BOD) features?
  The POR and BOD features are enabled by default. To handle them, ensure that the power supply is stable and within the recommended operating range. If a power failure occurs, the device will reset and restart when power is restored.
• What is the maximum clock accuracy of the PCF8523T/1, and how can it be calibrated?
  The maximum clock accuracy of the PCF8523T/1 is ±2 minutes per year. The clock can be calibrated by adjusting the clock correction registers (CLKCORR) to compensate for crystal oscillator frequency deviations.