MCP7940N 2 Low-Cost I C Real-Time Clock/Calendar with SRAM and Battery Switchover Device Selection Table Description: SRAM The MCP7940N series of low-power Real-Time Clocks Part Number (Bytes) (RTC) uses digital timing compensation for an accurate clock/calendar, a programmable output control for MCP7940N 64 versatility, a power sense circuit that automatically Features: switches to the backup supply. Using a low-cost 32.768 kHz crystal, it tracks time using several internal regis- Real-Time Clock/Calendar (RTCC), Battery ters. For communication, the MCP7940N uses the Backed: 2 I C bus. - Hours, Minutes, Seconds, Day of Week, Day, The clock/calendar automatically adjusts for months Month and Year with fewer than 31 days, including corrections for - Dual alarm with single output leap years. The clock operates in either the 24-hour On-Chip Digital Trimming/Calibration: or 12-hour format with an AM/PM indicator and - Range -127 to +127 ppm settable alarm(s) to the second, minute, hour, day of - Resolution 1 ppm the week, date or month. Using the programmable CLKOUT, frequencies of 32.768, 8.192 and 4.096 Programmable Open-Drain Output Control: kHz and 1 Hz can be generated from the external - CLKOUT with 4 selectable frequencies crystal. - Alarm output The device is fully accessible through the serial 64 Bytes SRAM, Battery Backed interface while VCC is between 1.8V and 5.5V, but can Automatic VCC Switchover to VBAT Backup operate down to 1.3V for timekeeping and SRAM Supply retention only. Power-Fail Time-Stamp for Battery Switchover The RTC series of devices are available in the standard Low-Power CMOS Technology: 8-lead SOIC, TSSOP, MSOP and 2x3 TDFN packages. - Dynamic Current: 400 A max read Package Types - Battery Backup Current: <700nA 1.8V 100 kHz and 400 kHz Compatibility MSOP ESD Protection >4,000V X1 1 8 VCC Packages include 8-Lead SOIC, TSSOP, 2x3 X2 2 7 MFP TDFN, MSOP TDFN V 3 6 SCL Pb-Free and RoHS Compliant BAT X1 1 8 VCC Temperature Ranges: VSS 4 5 SDA 7 MFP X2 2 - Industrial (I): -40C to +85C VBAT SCL 3 6 SOIC, TSSOP VSS 5 4 SDA 1 8 X1 VCC 2 7 X2 MFP 3 6 V SCL BAT 4 5 VSS SDA 2011 Microchip Technology Inc. DS25010A-page 1MCP7940N FIGURE 1-1: TYPICAL OPERATING CIRCUIT X1 RTCC VCC Time-Stamp/ SRAM Alarms X2 MFP 2 VBAT VBAT Switch I C SCL VSS SDA DS25010A-page 2 2011 Microchip Technology Inc. Oscillator