DATASHEET
REAL-TIME CLOCK WITH BATTERY BACKED NON-VOLATILE RAM IDT1338
IDT®
REAL-TIME CLOCK WITH BATTERY BACKED NON-VOLATILE RAM 1
IDT1338 REV S 111214
General Description
The IDT1338 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.
Applications
• Telecom (Routers, Switches, Servers)
• Handheld (GPS, Point of Sale POS terminals)
• Consumer Electronics (Set-Top Box, Digital Recording,
Network Applications, Digital photo frames)
• Office (Fax/Printers, Copiers)
• Medical (Glucometer, Medicine Dispensers)
• 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)
• Industrial temperature range (-40°C to +85°C)
Block Diagram
VCC
GND
V
BAT
SCL
SDA
Crystal inside package
for 16-pin SOIC ONLY
X1
X2
1 Hz/4.096 kHz/
8.192 kHz/32.768 kHz
SQW/OUT
Power
Control
I
2
C
Interface
32.768 kHz
Oscillator and
Divider
Control
Logic
MUX/
Buffer
Clock, Calendar
Counter
56 Byte
RAM
1 Byte
Control
7 Bytes
Buffer
