MCP7940NT-I/ST

Real Time Clock Overview

The MCP7940NT-I/ST is a battery-backed I2C Real-Time Clock/Calendar (RTCC) with 64-byte SRAM, manufactured by Microchip Technology. It operates within a supply voltage range of 1.8V to 5.5V and supports backup voltages from 1.3V to 5.5V. The device tracks time using internal counters for hours, minutes, seconds, day of week, date, month, and year, supporting both 12-hour and 24-hour formats. It features dual programmable alarms, on-chip digital trimming with ±1 PPM resolution, and automatic switchover to battery backup upon power failure. The component is housed in an 8-lead TSSOP package and is qualified to AEC-Q100 standards.

Real Time Clock Feature Summary

• Real-Time Clock/Calendar with leap year compensation through 2399
• 64-byte battery-backed SRAM for user data storage
• Dual programmable alarms with flexible comparison options
• On-chip digital trimming for oscillator calibration (±129 PPM range)
• Power-fail time-stamp logging for backup switchover events

Real Time Clock Applications

• Industrial systems requiring precise timekeeping
• Automotive electronics meeting AEC-Q100 qualification
• Data logging devices needing non-volatile memory retention
• Battery-powered embedded systems with low current requirements

Real Time Clock Procurement Notes

Verify the specific suffix 'T' against official documentation to confirm package type and temperature grade. Ensure compatibility with I2C bus pull-up resistor values based on the operating voltage and clock speed requirements. Confirm that the industrial temperature range (-40°C to +85°C) meets the application's environmental specifications.

Real Time Clock Selection Notes

Select this component when a combination of RTCC functionality and general-purpose non-volatile memory is required in a small footprint. Consider the low typical timekeeping current of 1.2 µA at 3.3V for battery life calculations. Ensure the design accommodates external load capacitors for the 32.768 kHz crystal if using the internal oscillator circuit.

Real Time Clock Part Context

The MCP7940N family includes variants such as MCP7940M and MCP7940NT, differing primarily in package types like MSOP, SOIC, and TSSOP. The 'I' designation indicates the Industrial temperature range. This part belongs to Microchip's line of battery-backed RTCs designed for cost-sensitive applications requiring reliable timekeeping and data retention.

Real Time Clock Replacement Considerations

Direct pin-to-pin replacements within the same package may include other MCP7940N variants with different suffixes indicating package changes (e.g., /SOIC, /MSOP). Verify that any substitute maintains the same I2C address map and register configuration to ensure software compatibility.