PCF2129AT datasheet(7/86 Pages) PHILIPS

7 / 86 page

PCF2129

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Product data sheet

Rev. 7 — 19 December 2014

7 of 86

NXP Semiconductors

PCF2129

Accurate RTC with integrated quartz crystal for industrial applications

32.768 kHz (default) down to 1 Hz for use as system clock, microcontroller clock, and

so on, can be chosen (see Table 15).

• The registers at addresses 10h and 11h are used for the watchdog timer functions.

The watchdog timer has four selectable source clocks allowing for timer periods from

less than 1 ms to greater than 4 hours (see Table 52). An interrupt is generated when

the watchdog times out.

• The registers at addresses 12h to 18h are used for the timestamp function. When the

trigger event happens, the actual time is saved in the timestamp registers (see

Section 8.11).

• The register at address 19h is used for the correction of the crystal aging effect (see

Section 8.4.1).

• The registers at addresses 1Ah and 1Bh are for internal use only.

• The registers 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. This prevents a faulty writing or reading of the clock and calendar during a carry

condition (see Section 8.8.8).

PCF2129AT Datasheet(PDF) 7 Page - NXP Semiconductors