DS3232
Extremely Accurate I
2
C RTC with
Integrated Crystal and SRAM
8
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Block Diagram
N
N
RST
V
CC
INT/SQW
CLOCK AND CALENDAR
REGISTERS
SRAM
USER BUFFER
(7 BYTES)
I
2
C INTERFACE AND
ADDRESS REGISTER
DECODE
POWER CONTROL
V
CC
V
BAT
GND
SCL
SDA
TEMPERATURE
SENSOR
CONTROL LOGIC/
DIVIDER
SQUARE-WAVE BUFFER;
INT/SQW CONTROL
CONTROL AND STATUS
REGISTERS
VOLTAGE REFERENCE;
DEBOUNCE CIRCUIT;
PUSHBUTTON RESET
OSCILLATOR AND
CAPACITOR ARRAY
X1
X2
DS3232
32kHz
Detailed Description
The DS3232 is a serial RTC driven by a temperature-
compensated 32kHz crystal oscillator. The TCXO pro-
vides a stable and accurate reference clock, and
maintains the RTC to within ±2 minutes per year accu-
racy from -40°C to +85°C. The TCXO frequency output
is available at the 32kHz pin. The RTC is a low-power
clock/calendar with two programmable time-of-day
alarms and a programmable square-wave output. The
INT
/SQW provides either an interrupt signal due to
alarm conditions or a square-wave output. The clock/cal-
endar provides seconds, minutes, hours, day, date,
month, and year information. The date at the end of the
month is automatically 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 indicator. The internal registers are
accessible though an I
2
C bus interface.
A temperature-compensated voltage reference and
comparator circuit monitors the level of V
CC
to detect