MCP79400-ISN Electronic components Real Time Clock I2C GP RTCC 64B
SRAM ID Backup Switching
Timekeeping Features
• Real-Time Clock/Calendar (RTCC):
- Hours, Minutes, Seconds, Day of Week, Day, Month, Year
- Leap year compensated to 2399
- 12/24-hour modes
• Oscillator for 32.768 kHz Crystals:
- Optimized for 6-9 pF crystals
• On-Chip Digital Trimming/Calibration:
- ±1 ppm resolution
- ±129 ppm
• Dual Programmable Alarms
• Versatile Output Pin:
- Clock output with selectable frequency
- Alarm output - General purpose output
• Power-Fail Timestamp:
- Time logged on switchover to and from Battery mode Low-Power
Features
• Wide Voltage Range:
- Operating voltage range of 1.8V to 5.5V
- Backup voltage range of 1.3V to 5.5V
• Low Typical Timekeeping Current:
- Operating from VCC: 1.2 µA at 3.3V
- Operating from battery backup: 925 nA at 3.0V
• Automatic Switchover to Battery Backup
User Memory
• 64-Byte Battery-Backed SRAM
• 64-Bit Protected EEPROM Area:
- Robust write unlock sequence
- EUI-48™ MAC address (MCP79401)
- EUI-64™ MAC address (MCP79402)
- Custom programming available
Operating Ranges
• 2-Wire Serial Interface, I2C Compatible:
- I2C clock rate up to 400 kHz
• Temperature Range:
- Industrial (I):
-40°C to +85°C Packages
• 8-Lead SOIC, MSOP, TSSOP and 2x3 TDFN
General Description
The MCP7940X Real-Time Clock/Calendar (RTCC) tracks time using
internal counters for hours, minutes, seconds, days, months, years,
and day of week. Alarms can be configured on all counters up to and
including months. For usage and configuration, the MCP7940X
supports I2C communications up to 400 kHz.
The open-drain, multi-functional output can be configured to assert
on an alarm match, to output a selectable frequency square wave or
as a general purpose output.
The MCP7940X is designed to operate using a 32.768 kHz tuning fork
crystal with external crystal load capacitors. On-chip digital
trimming can be used to adjust for frequency variance caused by
crystal tolerance and temperature.
SRAM and timekeeping circuitry are powered from the back-up supply
when main power is lost, allowing the device to maintain accurate
time and the SRAM contents. The times when the device switches over
to the back-up supply and when primary power returns are both
logged by the power-fail timestamp.
The MCP7940X features 64 bits of EEPROM which is only writable
after an unlock sequence, making it ideal for storing a unique ID
or other critical information. The MCP79401 and MCP79402 are
preprogrammed with EUI-48 and EUI-64 addresses, respectively.
Custom programming is also available
