MCP7940N-I/P

The MCP7940N-I/P is a low-power battery-backed Real-Time Clock/Calendar (RTC) with SRAM uses digital timing compensation for an accurate clock/calendar, a programmable output control for versatility and a power sense circuit that automatically switches to the backup supply. Using a 32.768kHz crystal, it tracks time using several internal registers. For communication, the MCP7940N uses the I²C™ bus. The clock/calendar automatically adjusts for months with fewer than 31 days, including corrections for leap years. The clock operates in either the 24 or 12-hour format with an AM/PM indicator and settable alarm(s) to the second, minute, hour, day of the week, date or month. Using the programmable CLKOUT, frequencies of 32.768, 8.192 and 4.096kHz and 1Hz can be generated from the external crystal. The device is fully accessible through the serial interface while VCC is between 1.8 and 5.5V, but can operate down to 1.3V for timekeeping and SRAM retention only.

• Leap year compensated to 2399
• On-chip digital trimming/calibration - 1PPM resolution, ±129PPM range
• Dual programmable alarms
• Clock output pin with selectable frequency
• Alarm output pin
• General purpose output pin
• Power-fail time-stamp - time logged on switchover to and from battery backup
• 64-byte battery-backed SRAM
• 2-wire serial interface, I²Câ„¢ compatible
• Low typical timekeeping current
• Automatic switchover to battery backup