PCF85063TP All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2015. All rights reserved.
Product data sheet Rev. 4 — 6 May 2015 4 of 52
NXP Semiconductors
PCF85063TP
Tiny Real-Time Clock/calendar
8. Functional description
The PCF85063TP contains 11 8-bit registers with an auto-incrementing register address,
an on-chip 32.768 kHz oscillator with integrated capacitors, a frequency divider which
provides the source clock for the Real-Time Clock (RTC) and calender, and an I
2
C-bus
interface with a maximum data rate of 400 kbit/s.
The built-in address register will increment automatically after each read or write of a data
byte up to the register 0Ah. After register 0Ah, the auto-incrementing will wrap around to
address 00h (see Figure 3
).
All 11 registers (see Table 5) are designed as addressable 8-bit parallel registers although
not all bits are implemented. The first two registers (memory address 00h and 01h) are
used as control and status register. The register at address 02h is an offset register
allowing the fine-tuning of the clock; and at 03h is a free RAM byte. The addresses 04h
through 0Ah are used as counters for the clock function (seconds up to years counters).
The Seconds, Minutes, Hours, Days, Months, and Years registers are all coded in Binary
Coded Decimal (BCD) format. When one of the RTC registers is written or read, the
contents of all time counters are frozen. Therefore, faulty writing or reading of the clock
and calendar during a carry condition is prevented.
Fig 3. Handling address registers
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