M41ST85YMX6

Real Time Clock Overview

The M41ST85YMX6 is a low-power serial real-time clock (RTC) and NVRAM supervisor manufactured by STMicroelectronics. It integrates a 32.768 kHz oscillator, clock/calendar counters, and 44 bytes of general-purpose RAM within a 28-lead SOIC package featuring an embedded crystal. The device operates on a 4.5V to 5.5V supply with an ultra-low battery current of 500nA maximum. It supports I²C communication at 400 kHz and includes features such as automatic battery switchover, programmable alarms, watchdog timer, and microprocessor power-on reset.

Real Time Clock Feature Summary

• Integrated 28-lead SOIC package with embedded 32kHz crystal
• I²C interface supporting 400 kHz bus speed
• Automatic battery switchover and write protection circuitry
• Built-in watchdog timer and programmable alarm functions

Real Time Clock Applications

• Microprocessor system supervision
• Data logging and timestamping applications
• Battery-backed memory systems requiring RTC functionality

Real Time Clock Procurement Notes

Verify component status as the M41ST85YMX6 may be discontinued or subject to limited availability. Confirm package variant compatibility, specifically the MX suffix indicating the embedded crystal option, against design requirements. Ensure voltage levels match the 4.5V to 5.5V operating range for the Y variant.

Real Time Clock Selection Notes

Select this component when a combined RTC, NVRAM supervisor, and embedded crystal solution is required in a 28-pin form factor. The M41ST85Y variant is specified for 5.0V systems with a power-fail deselect voltage between 4.20V and 4.50V. Consider the M41ST85W if a 3.0V operating voltage is needed instead.

Real Time Clock Part Context

This part belongs to the M41ST85 family of serial RTCs and NVRAM supervisors. The 'MX' suffix denotes the specific package configuration containing an embedded crystal, distinguishing it from standard SOIC packages that require external crystals or SNAPHAT tops. It serves as a timekeeper and system monitor for embedded controllers.

Real Time Clock Replacement Considerations

The M41ST85W is a pin-compatible alternative offering 3.0V operation instead of 5.0V. Verify that the lower supply voltage and different power-fail thresholds of the W variant are acceptable for the target application before substitution.