MCP7940N-I/SN

Real Time Clock Overview

The MCP7940N-I/SN is a battery-backed I2C Real-Time Clock/Calendar (RTCC) with 64-byte SRAM, manufactured by Microchip Technology. It operates within an industrial temperature range of -40°C to +85°C and supports a supply voltage of 1.8V to 5.5V. The device maintains time using a 32.768 kHz crystal or external clock input, featuring on-chip digital trimming for ±129 PPM accuracy. Key electrical parameters include a typical timekeeping current of 1.2 µA at 3.3V and backup current of 925 nA at 3.0V. It communicates via an I2C interface up to 400 kHz and includes dual alarms, power-fail time-stamping, and automatic switchover to battery backup.

Real Time Clock Feature Summary

• Real-Time Clock/Calendar with leap year compensation through 2399
• 64-byte battery-backed SRAM for user data storage
• On-chip digital trimming with ±1 PPM resolution and ±129 PPM range
• Dual programmable alarms and versatile multifunction output pin

Real Time Clock Applications

• Industrial systems requiring accurate timekeeping in harsh environments
• Battery-powered devices needing low standby current consumption
• Data logging applications utilizing power-fail time-stamp features
• Embedded systems integrating I2C-based real-time tracking

Real Time Clock Procurement Notes

Verify the 'I' suffix confirms the Industrial temperature grade (-40°C to +85°C). Confirm the '/SN' package designation corresponds to the 8-lead SOIC format. Ensure the specific revision matches the DS20005010J datasheet requirements for your design implementation.

Real Time Clock Selection Notes

Select this component when an I2C-compatible RTCC with integrated non-volatile memory is required. The wide voltage range (1.8V–5.5V) suits various logic levels. Consider the digital trimming feature if high precision is needed without external calibration components. Verify that the 8-pin SOIC footprint fits the PCB layout constraints.

Real Time Clock Part Context

This part belongs to the MCP7940N family, which also includes variants like the MCP7940M and MCP7940T. The 'I' indicates the industrial temperature rating, while 'E' denotes extended temperature. Other packages such as TSSOP, MSOP, and TDFN are available within the same functional family.

Real Time Clock Replacement Considerations

Direct substitutes within the same package and temperature grade include other MCP7940N-I/SN units from authorized distributors. Cross-family replacements like the MCP79411 require verification of register compatibility and pinout alignment.