New Features
Repetitive Alarms &
Temperature Compensation
Preliminary Information
2-Wire™ RTC
X1235
Real Time Clock/Calendar
FEATURES
• Modems
• Network Routers, Hubs, Switches, Bridges
• Real Time Clock/Calendar
• Cellular Infrastructure Equipment
• Fixed Broadband Wireless Equipment
• Pagers / PDA
• POS Equipment
• Test Meters / Fixtures
• Office Automation (Copiers, Fax)
• Home Appliances
• Computer Products
—Tracks time in Hours, Minutes, and Seconds
—Day of the Week, Day, Month, andYear
• 2 Polled Alarms (Non-volatile)
—Settable on the Second, Minute, Hour, Day of
the Week, Day, or Month
—Repeat Mode (periodic interrupts)
• Oscillator Compensation on chip
—Internal feedback resistor and compensation
capacitors
• Other Industrial / Medical / Automotive
—64 position Digitally Controlled Trim Capacitor
—6 digital frequency adjustment settings to
±±3ppm
• Battery Switch or Super Cap Input
• 2-Wire™ Interface interoperable with I2C*
—433kHz data transfer rate
• Low Power CMOS
—1.25µA Operating Current (Typical)
• Small Package Options
DESCRIPTION
The X1205 device is a Real Time Clock with clock/
calendar, two polled alarms, oscillator compensation,
and battery backup switch.
The oscillator uses an external, low-cost 32.768kHz
crystal. All compensation and trim components are
integrated on the chip. This eliminates several external
discrete components and a trim capacitor, saving
board area and component cost.
—8-Lead SOIC and 8-Lead TSSOP
APPLICATIONS
The Real-Time Clock keeps track of time with separate
registers for Hours, Minutes, and Seconds. The
Calendar has separate registers for Date, Month, Year
and Day-of-week. The calendar is correct through
2099, with automatic leap year correction.
• Utility Meters
• HVAC Equipment
• Audio / Video Components
• Set Top Box / Television
BLOCK DIAGRAM
OSC
Compensation
X1
X2
Timer
Calendar
Logic
Frequency
Divider
1Hz
32.768kHz
Oscillator
Time
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
*I2C is a Trademark of Philips.
REV 1.0.9 8/29/02
Characteristics subject to change without notice. 1 of 22
www.xicor.com
XICOR [ XICOR INC. ]
