Preliminary Information
16k (2k x 8)
X1243
Real Time Clock/Calendar/Alarm with EEPROM
2-Wire
™
RTC
FEATURES
• 2 alarms—interrupt output
—Settable on the second, 10s of seconds,
minute, 10s of minutes, hour, day, month, or
day of the week
—Repeat alarm for time base generation
• 2-wire interface interoperable with I
2
C
—400kHz data transfer rate
• Secondary power supply input with internal
switch-over circuitry
• 2Kbytes of EEPROM
—64-byte page write mode
—3-bit Block Lock
™
protection
• 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
• Small package options
—8-lead SOIC package, 8-lead TSSOP package
DESCRIPTION
The X1243 is a Real Time Clock with clock/calendar
circuits and two alarms. The dual port clock and alarm
registers allow 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 and
automatic adjustment for months with less than 31
days.
An alarm match of the RTC sets an interrupt flag and
activates an interrupt pin. An alternative alarm function
provides a pulsed interrupt for long time constant time-
bases.
The device offers a backup power input pin. This
V
BACK
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 X1243 provides a 2Kbyte EEPROM array, giving a
safe, secure memory for critical user and configuration
data. This memory is unaffected by complete failure of
the main and backup supplies.
BLOCK DIAGRAM
X1
Oscillator
X2
Frequency
Divider
1Hz
Timer
Calendar
Logic
32.768kHz
Time
Keeping
Registers
(SRAM)
Mask
Interrupt Enable
Alarm
SCL
SDA
Serial
Interface
Decoder
Control
Decode
Logic
Control
Registers
(EEPROM)
Status
Register
(SRAM)
Alarm
Compare
Alarm Regs
(EEPROM)
16k (2k x 8)
EEPROM
Array
8
IRQ
REV 1.1.4 5/31/01
www.xicor.com
Characteristics subject to change without notice.
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XICOR [ XICOR INC. ]
