MCP795W22T-I/SL

Real Time Clock Overview

The MCP795W22T-I/SL is a battery-backed SPI Real-Time Clock/Calendar manufactured by Microchip Technology. It features 2 Kbit EEPROM with an EUI-64™ MAC address, 64 bytes of SRAM, and dual programmable alarms. The device operates on a 32.768 kHz crystal or external clock input, supporting digital trimming for ±1 ppm resolution. Electrical specifications include a VCC range of 1.8V to 3.6V and a backup voltage range of 1.3V to 3.6V. Typical timekeeping current is 1.2 µA at 3.0V from VCC and 1.0 µA at 3.0V from VBAT. The industrial temperature range is -40°C to +85°C.

Real Time Clock Feature Summary

• Integrated 2 Kbit EEPROM with preprogrammed EUI-64™ MAC address and 64-byte battery-backed SRAM.
• Dual programmable alarms and power-fail timestamp logging for system robustness.
• On-chip digital trimming provides ±1 ppm resolution over a ±259 ppm adjustment range.
• Supports high-speed event detection and low-speed switch debouncing via dedicated inputs.

Real Time Clock Applications

• Industrial controllers requiring precise timekeeping and data retention during power loss.
• Smart meters and utility devices utilizing the integrated EUI-64™ address for identification.
• Medical equipment needing watchdog timer functionality and alarm interrupts.

Real Time Clock Procurement Notes

Verify the 'T' suffix indicates tape-and-reel packaging and the 'SL' suffix denotes the TSSOP-14 package. Confirm the 'I' designation matches the required industrial temperature range of -40°C to +85°C. Ensure the specific revision level aligns with your design requirements.

Real Time Clock Selection Notes

Select this model when an EUI-64™ identifier is required within the RTC memory. Compare against the MCP795W11 series if only 1 Kbit EEPROM is sufficient. Ensure the application voltage stays within the 1.8V to 3.6V operating range to maintain specified timing accuracy.

Real Time Clock Part Context

This component belongs to the MCP795WXX family of battery-backed SPI RTCCs. It shares functional similarities with the 10-pin MCP7952X series but offers expanded memory and additional I/O pins in a 14-lead package. The W22 variant specifically includes the larger 2 Kbit EEPROM capacity compared to the W21 or W20 variants.

Real Time Clock Replacement Considerations

Publicly confirmed substitutes include other members of the MCP795WXX family, such as the MCP795W21T-I/SL (EUI-48™) or MCP795W20T-I/SL (Blank EEPROM). Verify pin compatibility and memory size before substitution.

Real Time Clock FAQ

What is the purpose of the protected EEPROM area?

The 128-bit protected EEPROM area requires a robust write unlock sequence, making it suitable for storing critical information like the unique EUI-64™ MAC address.

How does the device handle power failure?

It automatically switches to the VBAT supply when VCC drops below the trip voltage. It logs the exact time of power loss and restoration using the Power-Fail Timestamp registers.

Can the oscillator be driven by an external clock?

Yes, an external 32.768 kHz clock source can be connected to the X1 pin while leaving the X2 pin floating, provided the EXTOSC bit is set.