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MCP7940M

MCHPMCP7940M

MPN: MCP7940MT-I/MNY
Microchip Technology
Real Time Clock (RTC) IC Clock/Calendar 64B I2C, 2-Wire Serial 8-WFDFN Exposed Pad
Active10,857 in stock
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Overview

The MCP7940M is a low-power Real-Time Clock (RTC) and calendar IC that communicates over a standard I2C interface. It includes 64 bytes of SRAM for general-purpose data storage and features digital trimming to compensate for crystal frequency drift. The device operates across a wide supply voltage range from 1.8V to 5.5V and consumes as little as 1.2uA of current.

Why Choose This Part

The wide 1.8V to 5.5V operating range makes it compatible with both legacy 5V systems and modern low-voltage MCUs. The inclusion of digital trimming allows for software-based calibration of the 32.768 kHz oscillator to maintain high accuracy without manual hardware adjustments.

Applications

Battery-Powered Timekeeping
Ideal for portable devices that require accurate time and date tracking with minimal power draw.
Event Logging
Utilizes the 64 bytes of SRAM to store system status or timestamp data during power-down states.
Scheduled System Wake-up
Uses the two internal alarms and square wave output to trigger external microcontrollers or peripherals at specific intervals.

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-WFDFN Exposed Pad
Voltage - Supply 1.8V ~ 5.5V
Operating Temperature -40degC ~ 85degC
Supplier Device Package 8-TDFN (2x3)
Current - Timekeeping (Max) 1uA @ 5.5V

Getting Started

Connect a standard 32.768 kHz tuning-fork crystal to the X1 and X2 pins with appropriate load capacitors. Communicate with the device using an I2C host at up to 400 kHz to set the initial time, date, and alarm registers.

MCP7940 Family

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

Part Number Package Current - Timekeeping (Max) Stock
MCP7940MT-I/MNY (this part) WFDFN-8 1uA 10,857
MCP7940NT-I/MS TSSOP-8 1.2uA 22,374
MCP7940NT-I/SN SOIC-8 1.2uA 32,168
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 / Analog Devices - A common 5V RTC alternative for designs that do not require low-voltage operation.
MCP79410 MCHPMicrochip Technology - Upgrade path that adds 128 bits of EEPROM and a unique ID for applications requiring non-volatile storage.