Data Sheet

Product data sheet Rev. 05 — 17 July 2007 4 of 32

NXP Semiconductors

PCF8563

Real time clock/calendar

6.2 Pin description

7. Functional description

The PCF8563 contains sixteen 8-bit registers with an auto-incrementing address register,

an on-chip 32.768 kHz oscillator with one integrated capacitor, a frequency divider which

provides the source clock for the Real Time Clock/calender (RTC), a programmable clock

output, a timer, an alarm, a voltage-low detector and a 400 kHz I

C-bus interface.

All 16 registers 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/or status registers. The memory addresses 02h through 08h are used as

counters for the clock function (seconds up to years counters). Address locations 09h

through 0Ch contain alarm registers which deﬁne the conditions for an alarm.

Address 0Dh controls the CLKOUT output frequency. 0Eh and 0Fh are the timer control

and timer registers, respectively.

The seconds, minutes, hours, days, weekdays, months, years as well as the minute alarm,

hour alarm, day alarm and weekday alarm registers are all coded in Binary Coded

Decimal (BCD) format.

When one of the RTC registers is read the contents of all counters are frozen. Therefore,

faulty reading of the clock/calendar during a carry condition is prevented.

7.1 Alarm function modes

By clearing the MSB of one or more of the alarm registers (bit AE = alarm enable), the

corresponding alarm condition(s) will be active. In this way an alarm can be generated

from once per minute up to once per week. The alarm condition sets the Alarm Flag (AF).

The asserted AF can be used to generate an interrupt (INT). The AF can only be cleared

by software.

Table 2. Pin description

Symbol Pin Description

DIP8, SO8,

TSSOP8

HVSON10

OSCI 1 1 oscillator input

OSCO 2 2 oscillator output

n.c - 3 not connected

INT 3 4 interrupt output (open-drain; active LOW)

4 5 ground

SDA 5 6 serial data input and output

SCL 6 7 serial clock input

CLKOUT 7 8 clock output, open-drain

8 9 positive supply voltage

n.c - 10 not connected