Overview
The M41ST85WMX6TR, produced by STMicroelectronics, is a versatile electronic component that combines the functions of a serial real-time clock (RTC), microprocessor supervisor, and NVRAM supervisor. Built using a low-power CMOS SRAM process, this device is designed to provide reliable timekeeping, memory supervision, and system monitoring. It features a 64-byte memory space, including 44 bytes of NVRAM and 20 memory-mapped RTC registers. The device is particularly useful in applications requiring precise timekeeping, automatic backup battery switchover, and robust system supervision.
Key Specifications
| Parameter | Value |
|---|---|
| Operating Voltage | 3.0/3.3 V (VCC = 2.7 to 3.6 V) |
| I²C Interface Frequency | 400 kHz |
| NVRAM Size | 44 bytes |
| RTC Registers | 20 (including clock, alarm, watchdog, flag, square wave, and control data) |
| Oscillator Frequency | 32.768 kHz (crystal-controlled) |
| Battery Supply Current | 500 nA (max) |
| Operating Temperature | –40°C to +85°C |
| Package Options | 28-lead SNAPHAT® IC (SOH28), 28-lead embedded crystal SOIC (SOX28) |
| RoHS Compliance | Yes, Lead-free second level interconnect |
Key Features
- Automatic battery switchover and WRITE protect for internal serial RTC and external low power SRAM (LPSRAM)
- 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
- Programmable alarm with repeat modes and power-down timestamp (HT bit)
- Programmable squarewave generator (1 Hz to 32 kHz)
- Non-volatile time-of-day clock/calendar with automatic corrections for month and year
- Battery monitor (battery low flag)
- SNAPHAT® package option for easy battery and crystal replacement
Applications
The M41ST85WMX6TR is suitable for a wide range of applications, including:
- Embedded systems requiring precise timekeeping and automatic backup
- Industrial control systems needing robust system supervision
- Medical devices that require reliable time and date functions
- Automotive systems where low power consumption and high reliability are crucial
- Consumer electronics such as set-top boxes, routers, and other network devices
Q & A
- What is the primary function of the M41ST85WMX6TR?
The primary function is to serve as a combination serial real-time clock, microprocessor supervisor, and NVRAM supervisor. - What is the operating voltage range of the M41ST85WMX6TR?
The operating voltage range is 2.7 to 3.6 V. - What is the frequency of the I²C interface?
The I²C interface operates at 400 kHz. - How much NVRAM does the device have?
The device has 44 bytes of NVRAM. - What is the oscillator frequency used in the RTC?
The oscillator frequency is 32.768 kHz, which is crystal-controlled. - What is the maximum battery supply current?
The maximum battery supply current is 500 nA. - What are the package options available for the M41ST85WMX6TR?
The package options include 28-lead SNAPHAT® IC (SOH28) and 28-lead embedded crystal SOIC (SOX28). - Is the M41ST85WMX6TR RoHS compliant?
Yes, it is RoHS compliant with lead-free second level interconnect. - What is the operating temperature range of the device?
The operating temperature range is –40°C to +85°C. - Does the device have a programmable watchdog timer?
Yes, it has a programmable watchdog timer with a time-out period ranging from 62.5 ms to 128 s.
