Overview
The M41ST85WMH6E is a versatile electronic component produced by STMicroelectronics, combining the functions of a serial real-time clock, microprocessor supervisor, and NVRAM supervisor. Built using a low-power CMOS SRAM process, this device is designed to provide accurate timekeeping and supervision capabilities in a wide range of applications. It features a 64-byte memory space, including 44 bytes of NVRAM and 20 memory-mapped RTC registers, and supports an I²C serial interface.
Key Specifications
| Parameter | Value |
|---|---|
| Operating Voltage Range | 2.7 V to 3.6 V |
| Operating Temperature Range | -40°C to 85°C |
| Package Type | SOH28 (28-lead plastic small outline, battery SNAPHAT®) |
| RoHS Compliance | Ecopack2 (Lead-free second level interconnect) |
| I²C Serial Interface Frequency | 400 kHz |
| Memory Space | 64 bytes (44 bytes NVRAM, 20 memory-mapped RTC registers) |
| Crystal Oscillator | 32 kHz with integrating load capacitance (12.5 pF) |
| Battery Supply Current | 500 nA (max) |
| Watchdog Time-out Period | 62.5 ms to 128 s |
| Power-fail Deselect Voltage | 2.60 V (nom) |
Key Features
- Automatic battery switchover and WRITE protect for internal serial RTC and external low power SRAM (LPSRAM)
- 400 kHz I²C serial interface
- Ultralow battery supply current of 500 nA (max)
- Programmable watchdog with 62.5 ms to 128 s time-out period
- Early power-fail warning circuit (PFI/PFO) with 1.25 V precision reference
- Power-on reset/low voltage detect with open drain reset output
- Non-volatile external LPSRAM supervision with automatic switchover to back-up battery and write protection
- Programmable squarewave generator (1 Hz to 32 kHz)
- RTC features including counters for seconds, minutes, hours, day, date, month, and year, as well as clock calibration and programmable alarm with repeat modes
Applications
- Industrial control systems requiring accurate timekeeping and supervision
- Medical devices that need reliable time and date tracking
- Consumer products such as smart home devices, appliances, and wearables
- Embedded systems in various sectors including automotive, aerospace, and IoT devices
Q & A
- What is the operating voltage range of the M41ST85WMH6E?
The operating voltage range is 2.7 V to 3.6 V. - What is the temperature range for the M41ST85WMH6E?
The operating temperature range is -40°C to 85°C. - What type of interface does the M41ST85WMH6E use?
The device uses a 400 kHz I²C serial interface. - How much memory does the M41ST85WMH6E have?
The device has a 64-byte memory space, including 44 bytes of NVRAM and 20 memory-mapped RTC registers. - What is the purpose of the watchdog timer in the M41ST85WMH6E?
The watchdog timer is programmable and can be set between 62.5 ms to 128 s to monitor the system and reset it if necessary. - Does the M41ST85WMH6E support battery backup?
Yes, it supports battery backup with automatic switchover and WRITE protect for internal serial RTC and external LPSRAM. - What is the maximum battery supply current of the M41ST85WMH6E?
The maximum battery supply current is 500 nA. - Can the M41ST85WMH6E generate a squarewave output?
Yes, it can generate a programmable squarewave output from 1 Hz to 32 kHz. - Is the M41ST85WMH6E RoHS compliant?
Yes, it is RoHS compliant with lead-free second level interconnect. - What package options are available for the M41ST85WMH6E?
The device is available in 28-lead SNAPHAT® IC (SOH28) and 28-lead embedded crystal SOIC (SOX28) packages.
