M41ST85WMH6TR

Real Time Clock Overview

The M41ST85WMH6TR is a Real-Time Clock (RTC) IC manufactured by STMicroelectronics, featuring an I2C interface and housed in a 28-SOIC package. It operates on a supply voltage of 2.7V to 3.6V with a maximum current consumption of 0.5mA at 2.7V. The device integrates a clock/calendar function, 44 bytes of NVRAM, and supports date formats including YY-MM-DD-dd and time formats HH:MM:SS:hh (24-hour). Key features include alarm capabilities, leap year compensation, square wave output, and a watchdog timer. It functions within a temperature range of -40°C to +85°C.

Real Time Clock Feature Summary

• Integrated RTC with 44-byte NVRAM and automatic backup battery switchover
• I2C serial interface supporting up to 400 kHz data rate
• Built-in microprocessor supervisor with watchdog timer and power-on reset
• Operates within -40°C to +85°C industrial temperature range

Real Time Clock Applications

• Smart grid distribution and smart metering systems
• Industrial control systems requiring precise timekeeping
• Consumer electronics with battery-backed memory requirements

Real Time Clock Procurement Notes

Verify the specific suffix MH6 against official STMicroelectronics documentation to confirm pinout and package dimensions for the SOH-28 variant. Ensure compatibility with system voltage levels (2.7V–3.6V) and I2C bus speeds. Confirm RoHS3 compliance status for environmental regulations. Check moisture sensitivity level (MSL 3) handling requirements during assembly.

Real Time Clock Selection Notes

Select this component when a combined RTC, NVRAM supervisor, and microprocessor supervisor is required in a compact 28-pin surface-mount package. Compare storage capacity (44B NVRAM) against alternatives like the M41ST87W if larger memory is needed. Verify that the 2.7V–3.6V operating range matches the target system's power supply constraints.

Real Time Clock Part Context

The M41ST85WMH6TR belongs to the M41ST85W series of serial real-time clocks. This series combines timekeeping, calendar functions, and non-volatile RAM supervision in a single low-power CMOS SRAM process. The 'MH6' suffix typically denotes specific packaging or tape-and-reel configurations for automated assembly.

Real Time Clock Replacement Considerations

The M41ST85YMX6 is a related part number within the same family but operates at 4.5V–5.5V and is marked as obsolete. Direct replacement requires verifying voltage compatibility and ensuring the 28-SOIC footprint matches the PCB design.