MCP7940M-I/P

Real Time Clock Overview

The MCP7940M-I/P is a Real-Time Clock/Calendar (RTCC) manufactured by Microchip Technology in an 8-lead PDIP package. It operates within a voltage range of 1.8V to 5.5V and supports an I2C interface with clock rates up to 400 kHz. The device maintains time using a 32.768 kHz crystal or external clock source, featuring on-chip digital trimming for ±129 PPM accuracy. It includes 64 bytes of SRAM, dual programmable alarms, and a multifunction output pin. The industrial temperature rating covers -40°C to +85°C.

Real Time Clock Feature Summary

• Real-Time Clock/Calendar with leap year compensation through 2399
• On-chip digital trimming with ±1 PPM resolution
• Dual programmable alarms with flexible comparison options
• 64-byte user-accessible SRAM

Real Time Clock Applications

• Timekeeping in microcontroller-based systems
• Data logging timestamping
• Alarm generation for periodic interrupts

Real Time Clock Procurement Notes

Verify the package type matches the required PCB footprint. Confirm the suffix indicates the industrial temperature range (-40°C to +85°C). Ensure the I2C bus pull-up resistors are correctly sized for the operating voltage and desired clock speed.

Real Time Clock Selection Notes

Select this component when a low-cost RTCC with integrated SRAM is needed. The PDIP package is suitable for through-hole prototyping. Verify that the system voltage falls within the 1.8V to 5.5V range. Consider the need for external load capacitors if using a crystal.

Real Time Clock Part Context

The MCP7940M series includes variants in SOIC, MSOP, TSSOP, and TDFN packages. The '-I' suffix denotes the industrial temperature range. The '/P' suffix specifically identifies the 8-lead Plastic Dual In-line Package. Other models in the family may lack SRAM or have different packaging options.

Real Time Clock Replacement Considerations

Check datasheets for alternative RTCCs with similar I2C interfaces and SRAM capacity. Verify pin compatibility if replacing directly in existing designs. Ensure the replacement supports the required voltage range and temperature specifications.