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DS3232M

Detailed Description

The DS3232M is a serial real-time clock (RTC) driven by

an internal, temperature-compensated, microelectrome-

chanical systems (MEMS) resonator. The oscillator pro-

vides a stable and accurate reference clock and main-

tains the RTC to within Q0.432 seconds-per-day accu-

racy from -40NC to +85NC. The RTC is a low-power clock/

calendar with two programmable time-of-day alarms. INT/

SQW provides either an interrupt signal due to alarm

conditions or a 1Hz square wave. The clock/calendar

provides seconds, minutes, hours, day, date, month, and

year information. The date at the end of the month is auto-

matically adjusted for months with fewer than 31 days,

including corrections for leap year. The clock operates in

either the 24-hour or 12-hour format with an AM/PM indi-

bus interface. A temperature-compensated voltage refer-

detect power failures and to automatically switch to the

backup supply when necessary. The RST pin provides

an external pushbutton function and acts as an indica-

tor of a power-fail event. Also available are 236 bytes of

general-purpose battery-backed SRAM.

Operation

The Block Diagram shows the device’s main elements.

Each of the major blocks is described separately in the

following sections.

Block Diagram

DS3232M

N

N

TIME-BASE

RESONATOR

TEMP

SENSOR

INTERRUPT

OR 1Hz

SELECT

DIVIDER

INT/SQW

1Hz

DIGITAL

ADJUSTMENT

FACTORY TRIM

N

32KHZ

GND

SDA

SCL

RST

CLOCK/CALENDAR

WITH ALARM

CONTROL AND STATUS

REGISTERS

SRAM

INTERFACE

POWER

CONTROL*

P

*SELECTED

POWER