The MCP7940N series of low-power Real-Time Clocks (RTC) 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 low-cost 32.768 kHz 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-hour 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 4.096 kHz and 1 Hz can be generated from the external crystal. The device is fully accessible through the serial interface while VCC is between 1.8V and 5.5V, but can operate down to 1.3V for timekeeping and SRAM retention only.
Additional Features Timekeeping
Battery-Backed Real-Time Clock/Calendar (RTCC)
Hours, Minutes, Seconds, Day of Week, Day, Month, Year
Leap year compensated to 2399
12/24 hour modes
On-Chip Digital Trimming/Calibration
1 PPM Resolution
±129 PPM Range
Dual Programmable Alarms
Versatile Output Pin
Clock output with selectable frequency
Alarm output
General Purpose output
Power-Fail Time-Stamp
Time logged on switchover to and from Battery Backup
64 Bytes Battery-Backed SRAM
2-Wire Serial Interface, I2C™Compatible
I2C Clock Frequency up to 400 kHz Low-Power
Wide Voltage Range
Operating Voltage 1.8V to 5.5V
Backup Voltage 1.3V to 5.5V
Low Typical Timekeeping Current
Automatic Switchover to Battery Backup
The MCP7940N series of low-power Real-Time Clocks (RTC) 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 low-cost 32.768 kHz 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-hour 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 4.096 kHz and 1 Hz can be generated from the external crystal. The device is fully accessible through the serial interface while VCC is between 1.8V and 5.5V, but can operate down to 1.3V for timekeeping and SRAM retention only.
Additional Features
Timekeeping
- Battery-Backed Real-Time Clock/Calendar (RTCC)
- Hours, Minutes, Seconds, Day of Week, Day, Month, Year
- Leap year compensated to 2399
- 12/24 hour modes
- On-Chip Digital Trimming/Calibration
- 1 PPM Resolution
- ±129 PPM Range
- Dual Programmable Alarms
- Versatile Output Pin
- Clock output with selectable frequency
- Alarm output
- General Purpose output
- Power-Fail Time-Stamp
- Time logged on switchover to and from Battery Backup
- 64 Bytes Battery-Backed SRAM
- 2-Wire Serial Interface, I2C™Compatible
- I2C Clock Frequency up to 400 kHz
Low-Power
- Wide Voltage Range
- Operating Voltage 1.8V to 5.5V
- Backup Voltage 1.3V to 5.5V
- Low Typical Timekeeping Current
- Automatic Switchover to Battery Backup
