pcf2127a NXP Semiconductors, pcf2127a Datasheet - Page 6

• Manufacturer Part Number: pcf2127a
• Description: Integrated Rtc, Tcxo And Quartz Crystal
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCF2127A_1
Product data sheet
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
Fig 3.
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The register 0Fh defines the temperature measurement period and the clock out
mode. The temperature measurement period can be selected from every 4 minutes
(default) down to every 30 seconds (see
32.768 kHz (default) down to 1 Hz for use as a system clock, a microcontroller clock
etc. can be chosen (see
Address registers 10h and 11h are used for the watchdog and countdown timer
functions. The timer has four selectable source clocks allowing for timer periods from
less than 1 ms to greater than 4 hours. Either the watchdog timer or the countdown
timer can be enabled (see
select whether an interrupt or a pulse on the reset pin will be generated when the
watchdog times out. For the countdown timer it is only possible that an interrupt will be
generated at the end of the countdown.
Address registers 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
Address register 19h is used for the correction of the crystal aging effect (see
Section
Address registers 1Ah and 1Bh define the RAM address. Address register 1Ch
(RAM_wrt_cmd) is the RAM write command; address register 1Dh (RAM_rd_cmd) is
the RAM read command. Data is transferred to or from the RAM via the serial
interface (see
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.
Handling address registers
8.12).
8.4.1).
Section
address register
Section
1Ch
1Dh
00h
01h
02h
03h
19h
1Ah
1Bh
Rev. 01 — 21 January 2010
...
8.9.8).
8.5).
Section
auto-increment
Section
not reachable by auto-inc. - needs to be addressed directly
not reachable by auto-inc. - needs to be addressed directly
8.3.2).
wrap around
8.11). For the watchdog timer it is possible to
Table
Integrated RTC, TCXO and quartz crystal
9). CLKOUT frequencies of
001aaj307
PCF2127A
© NXP B.V. 2010. All rights reserved.
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