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The X1228 device is a Real Time Clock with clock/calendar, two polled alarms with integrated 512x8 EEPROM, oscillator compensation, CPU Supervisor (POR/LVS and WDT) 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.

The Real-Time Clock keeps track of time with separate registers for Hours, Minutes, 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.

The powerful Dual Alarms can be set to any Clock/Calendar value for a match. For instance, every minute, every Tuesday, or 5:23 AM on March 21. The alarms can be polled in the Status Register or provide a hardware interrupt (IRQ Pin). There is a repeat mode for the alarms allowing a periodic interrupt.

The PHZ/IRQ pin may be software selected to provide a frequency output of 1Hz, 4096Hz, or 32,768Hz.

The X1228 device integrates CPU Supervisor functions and a Battery Switch. There is a Power-On Reset (RESET output) with typically 250ms delay from power-on. It will also assert RESET when V_CC goes below the specified threshold. The V_TRIP threshold is user reprogrammable. There is a WatchDog Timer (WDT) with three selectable time-out periods (0.25s, 0.75s, 1.75s) and a disabled setting. The watchdog activates the RESET pin when it expires.

The device offers a backup power input pin. This V_BACK pin allows the device to be backed up by battery or SuperCap. The entire X1228 device is fully operational from 2.7V to 5.5V and the clock/calendar portion of the X1228 device remains fully operational down to 1.8V (Standby Mode).

The X1228 device provides 4K bits of EEPROM with 8 modes of BlockLock™ control. The BlockLock allows a safe, secure memory for critical user and configuration data, while allowing a large user storage area.

Key Features

• Real Time Clock/Calendar
  • Tracks Time in Hours, Minutes, and Seconds
  • Day of the Week, Day, Month, and Year
• Two 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
  • 64 Position Digitally Controlled Trim Capacitor
  • Six Digital Frequency Adjustment Settings to ±30ppm
• CPU Supervisor Functions
  • Power-On Reset, Low Voltage Sense
  • Watchdog Timer (SW Selectable: 0.25s, 0.75s, 1.75s, off)
• Battery Switch or Super Cap Input
• 512 x 8 Bits of EEPROM
  • 64-Byte Page Write Mode
  • Eight Modes of Block Lock™ Protection
  • Single Byte Write Capability
• High Reliability
  • Data Retention: 100 Years
  • Endurance: 100,000 Cycles Per Byte
• 2-Wire™ Interface Interoperable with I2C
  • 400kHz Data Transfer Rate
• Frequency Output (SW Selectable: Off, 1Hz, 4096Hz, or 32.768kHz)
• Low Power CMOS
  • 1.25µA Operating Current (Typical)
• Small Package Options
  • 14 Ld SOIC and 14 Ld TSSOP
• Repetitive Alarms
• Temperature Compensation
• Pb-Free Plus Anneal Available (RoHS Compliant)

Applications

• Utility Meters
• HVAC Equipment
• Audio/Video Components
• Set Top Boxes/Televisions
• Modems
• Network Routers, Hubs, Switches, Bridges
• Cellular Infrastructure Equipment
• Fixed Broadband Wireless Equipment
• Pagers/PDAs
• POS Equipment
• Test Meters/Fixtures
• Office Automation (Copiers, Fax)
• Home Appliances
• Computer Products
• Other Industrial/Medical/Automotive