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MCP7940NT-I/MS

MCHPMCP7940NT-I/MS

Microchip Technology
Real Time Clock (RTC) IC Clock/Calendar 64B I2C, 2-Wire Serial 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
Active22,374 in stock
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Overview

The MCP7940NT-I/MS is a low-power I2C Real-Time Clock and Calendar (RTCC) featuring 64 bytes of integrated SRAM and a programmable square wave output. It handles full time-keeping functions including hours, minutes, seconds, days, months, and years with leap year compensation valid through 2099. Operating over a wide voltage range of 1.8V to 5.5V, it is designed for reliable timekeeping in battery-sensitive applications.

Why Choose This Part

The inclusion of 64 bytes of general-purpose SRAM allows for the storage of critical calibration data or state variables that must persist during clock operation. Its extremely low standby current of approximately 1.2 microamps and wide 1.8V to 5.5V supply range make it highly versatile for both 3.3V and 5V logic systems.

Applications

System Data Logging
Provides accurate timestamps for sensor data stored in external flash or the internal 64-byte SRAM.
Power-Timed Wakeup
Utilizes the programmable alarm and interrupt output to wake an MCU from deep sleep modes at specific intervals.
Smart Metering
Maintains precise timekeeping for utility meters and billing systems that require low power consumption.
Industrial Automation
Functions as a reliable local clock source for PLC modules and human-machine interfaces.

Key Specifications

Type Clock/Calendar
Features Alarm, Leap Year, Square Wave Output, SRAM
Interface I2C, 2-Wire Serial
Date Format YY-MM-DD-dd
Memory Size 64B
Time Format HH:MM:SS (12/24 hr)
Mounting Type Surface Mount
Package / Case 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
Voltage - Supply 1.8V ~ 5.5V
Operating Temperature -40degC ~ 85degC
Supplier Device Package 8-MSOP
Voltage - Supply, Battery 1.3V ~ 5.5V
Current - Timekeeping (Max) 1.2uA @ 3.3V

Getting Started

Interface the device via the I2C bus at speeds up to 400kHz and connect a 32.768 kHz crystal to the X1 and X2 pins. Use the MFP (Multi-Function Pin) as either an alarm interrupt or a square wave generator for MCU clock calibration. Microchip provides the MCP794XX driver library to simplify the configuration of the RTCC and SRAM registers.

MCP7940 Family

Comparing specs that differ across variants. The current part is highlighted.

Part Number Package Current - Timekeeping (Max) Stock
MCP7940NT-I/MS (this part) TSSOP-8 1.2uA 22,374
MCP7940NT-I/SN SOIC-8 1.2uA 32,168
MCP7940MT-I/MNY WFDFN-8 1uA 10,857
MCP7940M-I/SN SOIC-8 1uA 1,594
MCP7940MT-I/SN SOIC-8 1uA 2,696
MCP7940N-I/P DIP-8 1.2uA 1,254
Also available as: MCP7940N-I/SN, MCP7940N

Also Consider

DS1307 Maxim Integrated - A widely used alternative with 56 bytes of NV RAM, though it requires a 5V supply to operate.
DS3231 Maxim Integrated - Ideal if higher precision is required, as it features an integrated temperature-compensated crystal oscillator (TCXO).

Categories

Memory & Storage > EEPROM