MCP7940N-E/MS

Real Time Clock Overview

The MCP7940N-E/MS is a battery-backed I2C Real-Time Clock/Calendar (RTCC) with 64-byte SRAM, manufactured by Microchip Technology. It operates within an extended temperature range of -40°C to +125°C and supports a supply voltage of 1.8V to 5.5V. The device tracks time using internal counters for hours, minutes, seconds, day of week, date, month, and year, with leap year compensation through 2399. It features dual programmable alarms, on-chip digital trimming for ±129 PPM accuracy, and automatic switchover to backup power. The unit communicates via an I2C interface up to 400 kHz and is housed in an 8-lead MSOP package.

Real Time Clock Feature Summary

• Extended industrial temperature rating (-40°C to +125°C)
• Dual programmable alarms with flexible comparison options
• On-chip digital trimming with ±1 PPM resolution
• Automatic power-fail time-stamping

Real Time Clock Applications

• Battery-powered portable electronics requiring precise timekeeping
• Automotive systems requiring AEC-Q100 qualified components
• Industrial equipment operating in high-temperature environments

Real Time Clock Procurement Notes

Verify the 'E' suffix confirms the Extended temperature range (-40°C to +125°C). Confirm the '/MS' suffix indicates the 8-lead MSOP package. Ensure the specific revision matches the design requirements. Check RoHS compliance status as indicated in official documentation.

Real Time Clock Selection Notes

Select this variant when operation above 85°C is required. The standard 'I' version is limited to +85°C. Ensure the application utilizes an external 32.768 kHz crystal optimized for 6-9 pF load capacitance. Verify that the I2C bus speed does not exceed 400 kHz at voltages above 2.5V.

Real Time Clock Part Context

This component belongs to the MCP7940N family of RTCCs. The 'E' designation specifically denotes the Extended temperature grade, distinguishing it from the Industrial ('I') grade which is rated up to +85°C. Both share identical electrical characteristics and pinouts but differ in thermal endurance specifications.

Real Time Clock Replacement Considerations

The MCP7940N-I/MS is a functional substitute with identical pinout and features, limited to an industrial temperature range of -40°C to +85°C. Other packages in the family include SOIC, TSSOP, and TDFN variants.