Overview
The M41ST87WMX6, produced by STMicroelectronics, is a secure serial real-time clock (RTC) and non-volatile RAM (NVRAM) supervisor. This component is designed for low-power applications and features a 32.768 kHz oscillator, which is either internal (in the SOX28 package) or external (in the SSOP package). It operates at 5.0, 3.3, or 3.0 volts and includes a 400 kHz I2C bus interface. The device is equipped with 128 bytes of clearable NVRAM, a programmable alarm and interrupt function, and a watchdog timer. It also includes tamper detection circuits and an ultra-low battery supply current, making it suitable for a wide range of applications requiring precise timekeeping and data retention.
Key Specifications
| Parameter | Value |
|---|---|
| Operating Voltage | 5.0, 3.3, or 3.0 V |
| I2C Bus Frequency | 400 kHz |
| Oscillator Operating Voltage | 2.5 to 5.5 V |
| NVRAM Capacity | 128 bytes |
| Power-Fail Deselect Voltages | M41ST87W: THS = 1: VPFD ≈ 2.9 V; THS = 0: VPFD ≈ 2.63 V |
| Package Types | 28-lead SOIC with embedded crystal, 20-lead SSOP with external crystal |
| Battery Supply Current | Ultra-low, 500 nA (typ) |
| Temperature Range | -40 to 85 °C |
Key Features
- 5.0, 3.3, or 3.0 V operation with automatic switchover and deselect circuitry
- 400 kHz I2C bus interface
- 128 bytes of clearable, general-purpose NVRAM
- Programmable alarm and interrupt function, valid even during battery backup mode
- Programmable watchdog timer
- Unique electronic serial number (8-byte)
- 32 kHz frequency output available upon power-on
- Microprocessor power-on reset output
- Battery low flag
- Tamper indication circuits with timestamp and RAM clear
- LPSRAM clear function (TPCLR)
- Oscillator stop detection
Applications
The M41ST87WMX6 is suitable for various applications requiring precise timekeeping, data retention, and low power consumption. These include:
- Industrial control systems
- Medical devices
- Aerospace and defense systems
- Automotive systems
- Smart meters and energy management systems
- Security and surveillance systems
Q & A
- What are the operating voltage options for the M41ST87WMX6?
The M41ST87WMX6 operates at 5.0, 3.3, or 3.0 volts.
- What is the frequency of the I2C bus interface?
The I2C bus interface operates at 400 kHz.
- How much NVRAM does the M41ST87WMX6 have?
The device has 128 bytes of clearable, general-purpose NVRAM.
- Does the M41ST87WMX6 support tamper detection?
Yes, it includes tamper indication circuits with timestamp and RAM clear functionality.
- What are the package options for the M41ST87WMX6?
The device is available in a 28-lead SOIC package with an embedded crystal and a 20-lead SSOP package with an external crystal.
- How does the device handle power failures?
The device automatically switches to battery supply when a power failure occurs and includes power-fail deselect circuitry.
- What is the typical battery supply current of the M41ST87WMX6?
The typical battery supply current is 500 nA.
- Does the M41ST87WMX6 have a watchdog timer?
Yes, it includes a programmable watchdog timer.
- Is the M41ST87WMX6 suitable for high-temperature environments?
The device operates within a temperature range of -40 to 85 °C.
- How does the device communicate with other ICs?
The device uses a two-line, bidirectional I2C interface for communication.
