X1240 Datasheet, PDF (1/19 Pages) Xicor Inc. – Real Time Clock/Calendar with EEPROM

Preliminary Information
16K
X1240
2-Wire RTC
Real Time Clock/Calendar with EEPROM
FEATURES
• 2-Wire Interface interoperable with I²C.
—400kHz data transfer rate
• Secondary Power Supply Input with internal
switch-over circuitry.
• Year 2000 Compliant
• 2K bytes of EEPROM
—64 Byte Page Write Mode
—3 bit Block Lock
• Low Power CMOS
—<1µA Operating Current
—<3mA Active Current during Program
—<400µA Active Current during Data Read
• Single Byte Write Capability
• Typical Nonvolatile Write Cycle Time: 5ms
• High Reliability
—1,000,000 Endurance Cycles
—Guaranteed Data Retention: 100 Years
• Small Package Options
—8-Lead SOIC Package, 8L TSSOP Package
DESCRIPTION
The X1240 is a Real Time Clock with clock/calendar
circuits. The dual port clock register allows the clock to
operate, without loss of accuracy, even during read and
write operations.
The clock/calendar provides functionality that is con-
trollable and readable through a set of registers. The
clock, using a low cost 32.768kHz crystal input, accu-
rately tracks the time in seconds, minutes, hours, date,
day, month and years. It has leap year correction,
automatic adjustment for the year 2000 and months
with less than 31 days.
The device offers a backup power input pin. This
Vback pin allows the device to be backed up by a non-
rechargeable battery. The RTC is fully operational
from 1.8 to 5.5 volts.
The X1240 provides a 2K byte EEPROM array, giving
a safe, secure memory for critical user and configura-
tion data. This memory is unaffected by complete fail-
ure of the main and backup supplies.
BLOCK DIAGRAM
X1
32.768kHz
X2
Oscillator
Frequency 1Hz
Divider
Timer
Calendar
Logic
Time
Keeping
Registers
(SRAM)
SCL
SDA
Serial
Interface
Decoder
Control
Decode
Logic
8
Control
Registers
(EEPROM)
Status
Register
(SRAM)
16K
EEPROM
Array
©Xicor, Inc. 1994, 1995, 1996, 1997, 1998, 1999 Patents Pending
9900-3003.5 12/6/99 CM
1
Characteristics subject to change without notice