MCP79521-I/MS

Real Time Clock Overview

The MCP79521-I/MS is a battery-backed SPI Real-Time Clock/Calendar 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 3.6V. The device integrates 64 bytes of SRAM, 2 Kbits of EEPROM, and a preprogrammed EUI-48 MAC address in protected memory. Key features include dual programmable alarms, automatic power-fail switchover with timestamp logging, and on-chip digital trimming for oscillator calibration.

Real Time Clock Feature Summary

• Integrated 2 Kbit EEPROM and 64-byte battery-backed SRAM
• Preprogrammed EUI-48™ MAC address in protected EEPROM area
• Dual programmable alarms with interrupt generation via MFP pin
• Automatic power-fail switchover with Power-Up/Power-Down timestamps

Real Time Clock Applications

• Industrial systems requiring accurate timekeeping over wide temperature ranges
• Embedded devices needing non-volatile storage for unique identifiers or configuration data
• Battery-powered applications utilizing low standby current modes

Real Time Clock Procurement Notes

Verify the specific suffix 'I' indicates the Industrial temperature grade (-40°C to +85°C). Confirm package type 'MSOP' corresponds to the 10-lead Mini Small Outline Package. Ensure the ordering code matches the exact EEPROM capacity (2 Kbit) and Unique ID (EUI-48) requirements for the design.

Real Time Clock Selection Notes

Select this component when SPI interface compatibility is required alongside high-density non-volatile memory. The MCP79521 variant provides 2 Kbit EEPROM compared to the 1 Kbit in the MCP7951 series. Verify that the host microcontroller supports the necessary SPI clock rates up to 5 MHz at the operating voltage.

Real Time Clock Part Context

This part belongs to the MCP795XX family of RTCCs. The second digit '2' denotes 2 Kbit EEPROM capacity, while the third digit '1' specifies the inclusion of a factory-programmed EUI-48™ MAC address. This distinguishes it from variants with blank IDs or EUI-64 addresses.

Real Time Clock Replacement Considerations

The MCP79520T-I/MS serves as a functional substitute if the EUI-48™ MAC address is not required. Both parts share identical electrical characteristics, pinouts, and memory structures excluding the protected ID block.