DATASHEET
REAL-TIME CLOCK WITH BATTERY BACKED NON-VOLATILE RAM
IDT1338B-31
General Description
The IDT1338B-31 is a serial real-time clock (RTC) device
that consumes ultra-low power and provides a full
binary-coded decimal (BCD) clock/calendar with 56 bytes
of battery backed Non-Volatile Static RAM. The
clock/calendar provides seconds, minutes, hours, day, date,
month, and year information. The clock operates in either
the 24-hour or 12-hour format with AM/PM indicator. The
end of the month date is automatically adjusted for months
with fewer than 31 days, including corrections for leap year.
Access to the clock/calendar registers is provided by an I
2
C
interface capable of operating in fast I
2
C mode. Built-in
Power-sense circuitry detects power failures and
automatically switches to the backup supply, maintaining
time and date operation.
•
Others (Thermostats, Vending Machines, Modems, Utility
Meters)
Features
•
Real-Time Clock (RTC) counts seconds, minutes, hours,
day, date, month, and year with leap-year compensation
valid up to 2100
•
56-Byte battery-backed Non Volatile RAM for data
storage
•
•
•
•
Fast mode I
2
C Serial interface
Automatic power-fail detect and switch circuitry
Programmable square-wave output
Packaged in 8-pin MSOP, 8-pin SOIC, or 16-pin SOIC
(surface-mount package with an integrated crystal)
Applications
•
Telecom (Routers, Switches, Servers)
•
Handheld (GPS, Point of Sale POS terminals)
•
Consumer Electronics (Set-Top Box, Digital Recording,
Network Applications, Digital photo frames)
•
Industrial temperature range (-40°C to +85°C)
•
Office (Fax/Printers, Copiers)
•
Medical (Glucometer, Medicine Dispensers)
Block Diagram
Crystal inside package
for 16-pin SOIC ONLY
1 Hz/4.096 kHz/
8.192 kHz/32.768 kHz
X1
32.768 kHz
Oscillator and
Divider
MUX/
Buffer
SQW/OUT
X2
VCC
GND
V
BAT
SCL
SDA
I
2
C
Interface
56 Byte
RAM
1 Byte
Control
7 Bytes
Buffer
Power
Control
Control
Logic
Clock, Calendar
Counter
IDT™
REAL-TIME CLOCK WITH BATTERY BACKED NON-VOLATILE RAM 1
IDT1338B-31
REV A 112309
IDT [ INTEGRATED DEVICE TECHNOLOGY ]
