Philips Semiconductors

PCA8565

Real time clock/calender

Product data

Rev. 01 — 31 March 2003

3 of 26

9397 750 10695

© Koninklijke Philips Electronics N.V. 2003. All rights reserved.

7.2 Pin description

8.

Functional description

The PCA8565 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

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 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.

Fig 3.

Device diode protection diagram.

MCE169

SDA

4

5

VSS

SCL

3

6

INT

CLKOUT

2

7

OSCO

VDD

1

8

OSCI

PCA8565

Table 3:

Pin description

Symbol

Pin

Description

OSCI

1

oscillator input

OSCO

2

oscillator output

INT

3

interrupt output (open-drain; active LOW)

4

ground

SDA

5

serial data I/O

SCL

6

serial clock input

CLKOUT

7

clock output, open-drain

8

positive supply voltage