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