Overview
The M41ST87WMX6TR, produced by STMicroelectronics, is a secure serial real-time clock (RTC) and non-volatile RAM (NVRAM) supervisor. This component is designed to provide a comprehensive set of features for time-keeping, data storage, and system monitoring. It operates at multiple voltage levels (5.0, 3.3, or 3.0 V) and includes a 400 kHz I2C bus interface for communication. The device is equipped with a built-in 32.768 kHz oscillator and supports battery backup to ensure continuous operation during power failures.
Key Specifications
| Parameter | Value |
|---|---|
| Operating Voltage | 5.0, 3.3, or 3.0 V |
| I2C Bus Frequency | 400 kHz |
| Oscillator Frequency | 32.768 kHz |
| NVRAM Capacity | 128 bytes |
| Power-Fail Deselect Voltages | THS = 1: VPFD ≈ 2.9 V; THS = 0: VPFD ≈ 2.63 V (for 3.0-3.6 V VCC) |
| Package Types | 28-pin SOIC with embedded crystal, 20-pin SSOP with external crystal |
| Battery Backup Current | Ultra-low battery supply current of 500 nA (typ) |
| Temperature Range | –40 to 85 °C |
Key Features
- Non-volatile, time-of-day clock/calendar with counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, year, and century.
- Programmable alarm and interrupt function, valid even during battery backup mode.
- Programmable watchdog timer.
- Tamper detection circuits with timestamp and RAM clear.
- 128 bytes of clearable, general-purpose NVRAM.
- 32 kHz frequency output available upon power-on.
- Microprocessor power-on reset output.
- Battery low flag.
- Automatic switchover and deselect circuitry for power failure.
- Unique electronic serial number (8-byte).
Applications
The M41ST87WMX6TR is suitable for a variety of applications requiring precise time-keeping and non-volatile data storage. These include:
- Industrial control systems.
- Automotive systems.
- Medical devices.
- Consumer electronics.
- Security systems requiring tamper detection.
Q & A
- What are the operating voltage levels of the M41ST87WMX6TR?
The M41ST87WMX6TR operates at 5.0, 3.3, or 3.0 V. - What is the frequency of the I2C bus interface?
The I2C bus interface operates at 400 kHz. - What is the capacity of the NVRAM in the M41ST87WMX6TR?
The NVRAM capacity is 128 bytes. - How does the device handle power failures?
The device automatically switches to battery backup when a power failure occurs and includes power-fail deselect circuitry. - What are the package types available for the M41ST87WMX6TR?
The device is available in 28-pin SOIC with an embedded crystal and 20-pin SSOP with an external crystal. - What is the typical battery backup current of the M41ST87WMX6TR?
The typical battery backup current is 500 nA. - Does the M41ST87WMX6TR have tamper detection features?
Yes, it includes tamper detection circuits with timestamp and RAM clear. - What is the purpose of the watchdog timer in the M41ST87WMX6TR?
The watchdog timer is programmable and ensures the system remains operational by resetting it if it fails to respond within a specified time. - How does the device provide a reset signal?
The device provides a microprocessor power-on reset output. - Is the M41ST87WMX6TR suitable for high-temperature environments?
Yes, it operates within a temperature range of –40 to 85 °C.
