ISL1221

FN6316 Rev 1.00

Page 2 of 24

July 15, 2010

Block Diagram

INTERFACE

CONTROL

LOGIC

ALARM

FREQUENCY

OUT

RTC

DIVIDER

SDA

BUFFER

CRYSTAL

OSCILLATOR

POR

SWITCH

SCL

BUFFER

SDA

SCL

X1

X2

IRQ/

EVDET

INTERNAL

SUPPLY

Seconds

Minutes

Hours

Day of Week

Date

Month

Year

USER

SRAM

CONTROL

REGISTERS

EVIN

GND

Pin Descriptions

PIN

NUMBER

SYMBOL

DESCRIPTION

1X1

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.

2X2

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. X2 should be left open when X1 is driven from external source.

4GND

Ground.

5EVIN

Event Input (EVIN). The EVIN is an input pin that is used to detect an externally monitored event. When a high signal

is present at the EVIN pin an “event” is detected.

7SDA

Serial Data (SDA). 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.

8SCL

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

9IRQ/EVDET Interrupt (IRQ)/Event Detect (EVDET) Output. Multi-functional pin that can be used as interrupt for Alarm and Event

Detect. Open Drain Output.

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