NXP Semiconductors
PCF2129T
Accurate RTC with integrated quartz crystal for industrial
• The register at address 0Fh defines the temperature measurement period and the
clock out mode. The temperature measurement can be selected from every 4 minutes
(default) down to every 30 seconds (see Table 10). 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 11).
• 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 33). An interrupt will be 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).
PCF2129T
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 3 — 12 February 2013
© NXP B.V. 2013. All rights reserved.
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