2

FN8085.3

July 29, 2005

Block Diagram

INTERFACE

RTC

CONTROL

LOGIC

ALARM

FREQUENCY

OUT

RTC

DIVIDER

SDA

BUFFER

CRYSTAL

OSCILLATOR

POR

SWITCH

SCL

BUFFER

SDA

SCL

X1

X2

IRQ/

INTERNAL

SUPPLY

Seconds

Minutes

Hours

Day of Week

Date

Month

Year

USER

SRAM

CONTROL

REGISTERS

Pin Descriptions

PIN

NUMBER

SYMBOL

DESCRIPTION

1

X1

The X1 pin is the input of an inverting amplifier and is intended to be connected to one pin of an external 32.768kHz

quartz crystal. X1 can also be driven directly from a 32.768kHz source.

2

X2

The X2 pin is the output of an inverting amplifier and is intended to be connected to one pin of an external 32.768kHz

quartz crystal.

4

GND

Ground.

5

SDA

Serial Data (SDA) is a bidirectional pin used to transfer serial data into and out of the device. It has an open drain

output and may be wire OR’ed with other open drain or open collector outputs.

6

SCL

The Serial Clock (SCL) input is used to clock all serial data into and out of the device.

function is set via the configuration register.

Power supply.

ISL1208