M41ST87WSS6F

Real Time Clock Overview

The M41ST87WSS6F is a secure real-time clock (RTC) and NVRAM supervisor manufactured by STMicroelectronics. It features a built-in 32.768 kHz oscillator and 128 bytes of clearable non-volatile SRAM, organized as 160 bytes total with 8 bytes for clock/calendar functions. The device operates on a 2.7V to 3.6V supply voltage and communicates via a 400 kHz I²C interface. Key specifications include an operating temperature range of -40°C to +85°C and a maximum current consumption of 0.5mA at 2.7V–3.6V. It supports automatic power-fail switchover and tamper detection.

Real Time Clock Feature Summary

• Integrated 32.768 kHz internal crystal-controlled oscillator
• 128 bytes of user-accessible clearable NVRAM
• Automatic power-fail detection and battery backup switching
• Tamper detection capabilities for security monitoring

Real Time Clock Applications

• Smart grid distribution systems
• Smart metering applications
• Industrial control systems requiring time-stamping

Real Time Clock Procurement Notes

Verify the specific package variant, as the M41ST87W series includes both SOIC-28 and SSOP-20 options. Confirm that the 20-pin SSOP package matches the target PCB footprint. Check for end-of-life status or alternative recommendations from the manufacturer, as some variants in this family may be discontinued.

Real Time Clock Selection Notes

Select this component when a secure RTC with integrated NVRAM and tamper detection is required in a low-power environment. Ensure the system design accommodates the 2.7V–3.6V VCC range and utilizes an I²C bus capable of 400 kHz speeds. Verify that the 20-SSOP package dimensions fit the mechanical constraints of the enclosure.

Real Time Clock Part Context

This part belongs to the M41ST87W family of secure serial RTCs. It shares core functionality with the M41ST87WMX6 but differs in packaging (SSOP-20 vs. SOIC-28). The 'W' suffix indicates operation within the 3.0V/3.3V voltage domain, while 'Y' variants support 5.0V operation.

Real Time Clock Replacement Considerations

The M41ST87WMX6 is a pin-compatible alternative within the same family, differing only in the SOIC-28 package instead of SSOP-20. No other direct substitutes are confirmed in the provided documentation.