2-Wire™ RTC
X1203
Real Time Clock/Calendar/Alarm
DESCRIPTION
FEATURES
• 2 alarms—interrupt output
—Settable on the second, minute, hour, day,
month, or day of the week
—Repeat alarm for time base generation
• 2-wire interface interoperable with I2C
—400kHz data transfer rate
• Secondary power supply input with internal
switch-over circuitry
• Low power CMOS
—<1µA operating current
—<3mA active current during program
—<400µA active current during data read
• Typical nonvolatile write cycle time: 5ms
• High reliability
The X1203 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,
automatic adjustment for the year 2000 and 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.
• Small package options
—8-lead SOIC package, 8-lead TSSOP package
The device offers a backup power input pin. This
V
pin allows the device to be backed up by a non-
BACK
rechargeable battery. The RTC is fully operational from
2.7 to 5.5 Volts and the RTC portion of the X1203
device remains fully operational down to 1.8 Volts.
BLOCK DIAGRAM
X1
Timer
Calendar
Logic
Frequency
Divider
1Hz
32.768kHz
Oscillator
Time
X2
Keeping
Registers
(SRAM)
Control
Status
Control
Decode
Logic
Compare
Registers
Registers
Alarm
(EEPROM)
(SRAM)
Serial
Interface
Decoder
SCL
SDA
Alarm Regs
(EEPROM)
8
Interrupt Enable
Alarm
IRQ
Characteristics subject to change without notice. 1 of 19
REV 1.2.0 2/13/01 James Tsang
www.xicor.com