MCP795B21-I/SL

Real Time Clock Overview

The MCP795B21-I/SL is a low-power SPI Real-Time Clock/Calendar (RTCC) from Microchip Technology, housed in a 14-lead SOIC or TSSOP package. It features a 32 kHz boot-up clock at power-up, 64 bytes of battery-backed SRAM, and 2 Kbit of EEPROM with software write protection. The device supports dual programmable alarms, a watchdog timer, and event detection inputs. Operating voltage ranges from 1.8V to 5.5V on VCC and 1.3V to 5.5V on VBAT. It includes an on-chip digital trimming/calibration system with ±255 PPM range and a unique EUI-48™ ID.

Real Time Clock Feature Summary

• Integrated 32 kHz boot-up clock output at power-up via CLKOUT/BOOT pin
• 2 Kbit EEPROM and 64-byte battery-backed SRAM for data retention
• Dual configurable event detect inputs (EVHS/EVLS) and programmable watchdog timer
• On-chip digital calibration with ±255 PPM range in 1 PPM steps

Real Time Clock Applications

• Systems requiring accurate timekeeping with automatic battery switchover
• Applications needing millisecond-resolution alarms via SPI interface
• Devices utilizing preprogrammed EUI-48™ MAC addresses for identification
• Industrial environments operating between -40°C and +85°C

Real Time Clock Procurement Notes

Verify the specific package variant (SOIC vs. TSSOP) as the 'SL' suffix denotes the physical footprint. Confirm that the EUI-48™ Unique ID is required, as this model includes it preprogrammed. Ensure the design accommodates the 32 kHz boot-up feature if not needed, as it consumes power during startup.

Real Time Clock Selection Notes

Select this part over the MCP795W21 series specifically for the mandatory 32 kHz boot-up clock functionality. Choose the I/SL variant for industrial temperature range (-40°C to +85°C) and the specified package. Verify that the 2 Kbit EEPROM capacity meets storage needs compared to the 1 Kbit variants.

Real Time Clock Part Context

This component belongs to the MCP795BXX family, distinguished by the inclusion of a 32 kHz boot-up clock. It sits alongside the MCP795WXX series which lacks this feature. The '21' designation indicates 2 Kbit EEPROM and EUI-48™ ID, while 'I' specifies the industrial temperature grade.

Real Time Clock Replacement Considerations

The MCP795W21-I/SL is a functional substitute if the 32 kHz boot-up clock is not required. Other MCP795B21 variants with different packages (e.g., MSOP) may be used if pin compatibility allows.