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 NXP Semiconductors

  • PCA8565 Application Circuit

  • Created: Dec 09, 2014

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The PCA8565 plays a very important role in the real time systems like digital clock, attendance system and tariff switching. In applications where timestamp is needed, PCA8565 real time clock is a good option. It provides the following benefits: low power consumption, allows the main system for time-critical tasks, and more accurate than other methods.

The PCA8565 is a CMOS real time clock and calendar optimized for low power consumption. A programmable clock output, interrupt output and voltage-low detector are also provided. All address and data are transferred serially via a two-line bidirectional I2C-bus with a maximum bus speed of 400kbps. The built-in word address register is incremented automatically after each written or read data byte. It provides a year, month, day, weekday, hours, minutes and seconds based on a 32.768kHz quartz crystal. It features alarm and timer functions, low current, and extended operating temperature range of -40 degrees Celsius to +125 degrees Celsius. It further contains an 8-bit year register that can hold values from 00 to 99 in BCD format, which also compensates for leap years, thus leap year is automatically corrected.

From the application circuit, the PCA8565 can be used to perform standard RTC functions, such as tracking the actual time and date, or acting as a reference timer. To support power management, the PCA8565 can be used to wake the microcontroller from hibernation mode. In systems that use a PLL, it can serve as a system reference clock for the PLL input. The PCA8565 can also be used as a watchdog timer, or as an activation timer to start measurements or initiate other functions.



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