Overview
The M41T56 is a low-power, serial real-time clock (RTC) developed by STMicroelectronics. This component features 56 bytes of non-volatile RAM (NVRAM) and is designed for applications requiring precise timekeeping and data storage. The M41T56 includes a built-in 32,768 Hz oscillator, which is external crystal controlled, and the first 8 bytes of the RAM are dedicated to the clock/calendar function in binary-coded decimal (BCD) format. The device supports a two-line, bidirectional I²C bus for serial data transfer and has an automatic power-fail detect and switch circuitry to ensure continuous operation during power failures using a small lithium coin cell.
Key Specifications
| Specification | Value |
|---|---|
| Package Type | 8-lead plastic SOIC (SO8) |
| Supply Voltage | 5 V ±10% |
| Operating Temperature | –40 °C to 85 °C |
| Oscillator Frequency | 32,768 Hz (external crystal controlled) |
| NVRAM Size | 56 bytes |
| Serial Interface | I²C bus (100 kHz protocol) |
| Battery Supply Current | 450 nA (typ at 3 V) |
| Data Retention Time | In excess of 10 years with a 50 mAh, 3 V lithium cell |
| RoHS Compliance | Ecopack3 |
Key Features
- Counters for seconds, minutes, hours, day, date, month, years, and century
- 32 KHz crystal oscillator integrating load capacitance (12.5 pF) for exceptional oscillator stability
- Ultra-low battery supply current of 450 nA (typ at 3 V)
- Timekeeping down to 2.5 V
- Automatic power-fail detect and switch circuitry
- 56 bytes of general-purpose RAM
- Software clock calibration to compensate for crystal deviation due to temperature
- Automatic leap year compensation
- Operating temperature range of –40 °C to 85 °C
Applications
The M41T56 is suitable for a variety of applications that require accurate timekeeping and low power consumption. These include:
- Industrial control systems
- Medical devices
- Consumer electronics
- Automotive systems
- Data loggers and monitoring systems
Q & A
- What is the primary function of the M41T56?
The primary function of the M41T56 is to serve as a low-power, serial real-time clock (RTC) with additional non-volatile RAM (NVRAM) for data storage.
- What type of oscillator does the M41T56 use?
The M41T56 uses a 32,768 Hz crystal oscillator, which is external crystal controlled.
- What is the maximum operating temperature of the M41T56?
The maximum operating temperature of the M41T56 is 85 °C.
- How much NVRAM does the M41T56 have?
The M41T56 has 56 bytes of non-volatile RAM (NVRAM).
- What is the typical battery supply current of the M41T56?
The typical battery supply current of the M41T56 is 450 nA at 3 V.
- Does the M41T56 support automatic leap year compensation?
- What is the data retention time of the M41T56 with a 50 mAh, 3 V lithium cell?
The data retention time is in excess of 10 years with a 50 mAh, 3 V lithium cell.
- Is the M41T56 RoHS compliant?
- What type of serial interface does the M41T56 use?
The M41T56 uses an I²C bus with a 100 kHz protocol.
- What is the package type of the M41T56?
The M41T56 is supplied in an 8-lead plastic SOIC (SO8) package.
