PCF2131 datasheet(6/85 Pages) NXP

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NXP Semiconductors

PCF2131

Nano-power highly accurate RTC with integrated quartz crystal

• The registers at addresses 0Eh through 12h define the alarm function. It can be selected that an interrupt is

generated when an alarm event occurs (see Section 7.10).

• The register at address 13h defines the temperature measurement period and the clock out mode. The

temperature measurement can be selected from every 32 minutes (default) down to every 4minutes (see

Table 17). CLKOUT frequencies of 32.768 kHz (default) down to 1 Hz for use as system clock, microcontroller

clock, and so on, can be chosen (see Table 18).

• The registers at addresses 14h to 2Fh are used for the timestamp function. When the trigger event happens,

the actual time is saved in the timestamp registers (see Section 7.12).

• The register at address 30h is used for the correction of the crystal aging effect (see Section 7.4.1).

• The registers at addresses 31h to 34h are used for interrupt configration.

• The registers at addresses 35h and 36h are used for the watchdog timer functions. The watchdog timer has

four selectable source clocks allowing for timer periods from less than 20 ms to greater than 4 hours (see

Table 59). An interrupt is generated when the watchdog times out.

• The registers 100th Seconds, Seconds, Minutes, Hours, Days, Months, and Years are all coded in Binary

Coded Decimal (BCD) format to simplify application use. Other registers are either bit-wise or standard binary.

When one of the RTC registers is written or read, the content of all counters is temporarily frozen, all registers

hold their state during SPI or I2C transactions. The time stamp registers would update as soon as the bus

transaction completes. This prevents a faulty writing or reading of the clock and calendar during a carry

condition (see Section 7.9.9).

PCF2131

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Product data sheet

Rev. 2.0 — 5 October 2023

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PCF2131 Fiches technique(PDF) 6 Page - NXP Semiconductors