M41ST87WMX6

Real Time Clock Overview

The M41ST87WMX6 is a secure serial real-time clock (RTC) and NVRAM supervisor manufactured by STMicroelectronics. It integrates a low-power static CMOS SRAM organized as 160 bytes by 8 bits, with 128 bytes available for user data. The device features a built-in 32.768 kHz oscillator and supports I2C interface communication. Operating voltage ranges from 2.7V to 3.6V, with a maximum timing current of 0.5mA at this supply range. It includes automatic power-fail detection and battery switchover capabilities.

Real Time Clock Feature Summary

• Integrated RTC with calendar functions supporting leap year correction and BCD format timekeeping
• 128-byte non-volatile RAM (NVRAM) with tamper detection and watchdog timer
• Automatic power-fail detection with seamless switch to backup battery supply
• I2C bidirectional serial interface operating up to 400 kHz

Real Time Clock Applications

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

Real Time Clock Procurement Notes

Verify component status as the M41ST87WMX6 variant may be listed as obsolete or discontinued in some distributor databases. Confirm availability through official STMicroelectronics channels or authorized partners. Check for alternative packaging options such as the tape-and-reel version (M41ST87WMX6TR) if higher volume procurement is required. Ensure compliance with RoHS and REACH regulations before integration.

Real Time Clock Selection Notes

Select the M41ST87WMX6 when a combined RTC and NVRAM solution with tamper detection is required. Ensure the system operates within the 2.7V to 3.6V supply voltage range. Verify that the I2C bus speed does not exceed 400 kHz. Consider the M41ST87YMX6 if a 5V supply is necessary, noting its different voltage specifications and potential obsolescence status.

Real Time Clock Part Context

This component belongs to the M41ST87 series of secure serial RTCs and NVRAM supervisors. The 'W' suffix typically denotes the 3.3V/3.0V operation variant, distinguishing it from the 'Y' variant which supports 5.0V operation. The package is a 28-SOIC (0.295 inch width).

Real Time Clock Replacement Considerations

The M41ST87YMX6 is a related part number within the same family but operates at 5.0V. Direct substitution requires verifying voltage compatibility and pinout consistency. No other direct cross-model substitutes are confirmed in public documentation.