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Microchip Technology MCP79401T-I/MNY
- Part No.:
- MCP79401T-I/MNY
- Manufacturer:
- Microchip Technology
- Category:
- Real Time Clocks
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
MCP79401T-I/MNY.pdf
- Description:
- IC RTC CLK/CALENDAR I2C 8TDFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
MCP79401T-I/MNY from Microchip Technology is a battery-backed I²C Real-Time Clock/Calendar (RTCC) IC with integrated 64-byte SRAM, 8-byte protected EEPROM preprogrammed with EUI-48™ MAC address, digital trimming (±1 ppm resolution), dual programmable alarms, and power-fail timestamp logging. It operates from 1.8V–5.5V main supply and 1.3V–5.5V backup, consuming only 1.2 µA at 3.3V for timekeeping - used in industrial metering, embedded controllers, and smart sensors requiring persistent timekeeping during power loss.
For engineers reviewing the MCP79401T-I/MNY datasheet, MCP79401T-I/MNY pinout, MCP79401T-I/MNY application, or MCP79401T-I/MNY equivalent, key selection criteria include its ±1 ppm digital trim capability, 925 nA battery-backup current at 3.0V, I²C interface up to 400 kHz, EUI-48™ address storage, and automatic VCC/VBAT switchover with timestamp capture on power transitions.
Technical Context
The MCP79401T-I/MNY implements a fully autonomous RTCC subsystem using an internal 32.768 kHz oscillator circuit optimized for 6–9 pF crystals, with on-chip digital trimming (±129 ppm range, ±1 ppm resolution) to compensate crystal tolerance and temperature drift. Its alarm logic supports independent match conditions on seconds through months, with two configurable interrupt outputs via the MFP pin.
Power management includes automatic switchover between VCC and VBAT at 1.3–1.7 V threshold, with dedicated registers (PWRDNxxx/PWRUPxxx) capturing timestamps of both power-loss and power-restoration events. The I²C slave interface uses fixed addresses: 0xD8/D9 for RTCC/SRAM and 0xA8/A9 for EEPROM, with separate control bytes and no address configuration required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 32.768 kHz nominal - drives all timekeeping counters with leap-year compensation to year 2399 |
| Timekeeping Current (VCC) | 1.2 µA at 3.3V - enables multi-year operation from coin-cell backup when main power fails |
| Backup Current (VBAT) | 925 nA at 3.0V - ensures >10-year SRAM and RTC retention on CR2032 battery |
| I²C Speed | Up to 400 kHz - supports fast register access and EEPROM writes without bus contention |
| Digital Trim Resolution | ±1 ppm - allows fine-grained calibration against reference clocks for <±2 ppm annual accuracy |
| Protected EEPROM | 8 bytes preprogrammed with EUI-48™ - provides factory-assigned unique network identity, write-protected by unlock sequence |
| Alarm Capability | Dual independent alarms - each configurable to trigger on any combination of seconds, minutes, hours, date, weekday, or month |
Pinout & Package
Package: 8-pin TDFN (2 mm × 3 mm, exposed pad). Pinout matches SOIC/MSOP/TSSOP footprints (pin-compatible across all 8-lead packages).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| X1 | Crystal input / external clock input | Accepts 32.768 kHz crystal (with 6–9 pF load caps) or buffered square-wave clock; enables EXTOSC mode |
| X2 | Crystal output | Drives crystal in fundamental mode; must be left floating if external clock is used on X1 |
| VBAT | Backup supply input | Provides power to RTC, SRAM, and registers during VCC loss; switchover threshold 1.3–1.7 V |
| VSS | Ground reference | Common return for all analog/digital circuits; exposed pad recommended tied to VSS |
| SDA | I²C bidirectional data line | Open-drain, requires external pull-up; supports standard/fast-mode I²C up to 400 kHz |
| SCL | I²C clock input | Master-generated clock; timing compliant with I²C specification for 100/400 kHz modes |
| MFP | Multi-function open-drain output | Configurable as alarm pulse, selectable-frequency square wave (32.768 kHz down to 1 Hz), or GPIO |
| VCC | Main power supply | 1.8–5.5 V operation; powers I²C interface, EEPROM programming, and active timekeeping |
Key Features
| Feature | Design Value |
|---|---|
| Power-fail timestamp logging | Captures exact time of VCC dropout and restoration in dedicated PWRDNxxx/PWRUPxxx registers - critical for event forensics in energy meters |
| EUI-48™ MAC address storage | Factory-programmed 48-bit IEEE identifier in protected EEPROM - eliminates need for external ID storage or firmware provisioning |
| Dual independent alarms | Each alarm supports maskable match on all time/date fields (including weekday and month) - enables complex scheduling without host CPU intervention |
| On-chip digital trimming | ±129 ppm adjustment range with ±1 ppm resolution - achieves high accuracy without external trim capacitors or calibration hardware |
| Low-power oscillator architecture | Optimized for 6–9 pF crystals with internal biasing - reduces layout sensitivity and improves startup reliability over temperature |
| Buffered RTCC register reads | Hardware latching prevents rollover corruption during multi-byte reads - ensures atomic time/date acquisition in real-time systems |
Applications
| Smart Energy Metering | Industrial PLC HMI |
|---|---|
Use Scenario: Utility-grade electricity meter logging consumption every 15 minutes with tamper-proof time stamps. IC Role / Device Role / Timing Role: Primary time source maintaining calendar-correct billing intervals and power-loss event logs. Use Value: Power-fail timestamp captures exact moment of mains interruption; EUI-48™ enables secure device identity for remote firmware updates and grid authentication. |
Use Scenario: Human-machine interface panel in factory automation requiring local time-stamped diagnostics and scheduled maintenance alerts. IC Role / Device Role / Timing Role: Standalone RTCC providing wall-clock time, alarm-triggered notifications, and persistent session logging. Use Value: Dual alarms drive visual/audible warnings at configurable intervals; 64-byte SRAM stores last 10 fault codes with precise timestamps. |
| Medical Sensor Hub | IoT Edge Gateway |
Use Scenario: Portable patient monitor logging vital signs with FDA-compliant audit trail including power-cycle history. IC Role / Device Role / Timing Role: Certified timekeeper ensuring traceable, battery-backed timestamping for clinical data records. Use Value: 925 nA VBAT current extends CR2032 life beyond 5 years; power-fail timestamps satisfy regulatory requirements for event sequencing. |
Use Scenario: Cellular-connected gateway aggregating sensor data and transmitting time-synchronized batches to cloud every hour. IC Role / Device Role / Timing Role: Local time anchor enabling consistent data windowing and NTP-free synchronization during network outages. Use Value: Digital trimming maintains <±2 ppm accuracy across -40°C to +85°C; I²C interface allows low-pin-count integration with host MCU. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar real-time clock/calendar applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS3231M+ | Integrated TCXO (±2 ppm over -40°C to +85°C); higher 1.5 µA VCC current; no protected EEPROM or EUI-48™ | Better stability in wide-temp environments; lacks factory-programmed MAC address and power-fail timestamp registers | Select DS3231M+ when absolute temperature stability outweighs need for network identity or forensic power-event logging |
| MCP79402T-I/MNY | Identical pinout and feature set except preprogrammed EUI-64™ (64-bit) instead of EUI-48™; same SRAM, alarms, trimming, and timestamp functionality | Used where 64-bit node addressing is mandated (e.g., IPv6-based IoT deployments) | Select MCP79402T-I/MNY only when EUI-64™ is explicitly required; otherwise MCP79401T-I/MNY offers identical timing performance with smaller MAC footprint |
Compared with DS3231M+, MCP79401T-I/MNY trades TCXO-level stability for integrated EUI-48™ identity and power-fail forensics; compared with MCP79402T-I/MNY, it delivers identical timing accuracy and functionality but with 48-bit rather than 64-bit factory-assigned addressing - reducing memory overhead in constrained-edge firmware.
Availability
MCP79401T-I/MNY is available at Aetrix Electronics and suitable for industrial metering, medical sensor hubs, and IoT edge gateways requiring stable component supply, long-term lifecycle support, and guaranteed traceability.
Supply support for MCP79401T-I/MNY includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Microchip Technology Inc. is a leading provider of microcontrollers, analog components, and timing solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The MCP7940X family is designed specifically for embedded systems needing highly accurate, low-power, battery-backed timekeeping with integrated memory and event logging - targeting metering, industrial control, and connected devices.
FAQ
What is the primary function of the MCP79401T-I/MNY?
The MCP79401T-I/MNY is a battery-backed I²C Real-Time Clock/Calendar IC that maintains accurate time and date (with leap-year compensation to 2399), stores 64 bytes of SRAM and 8 bytes of protected EEPROM preprogrammed with EUI-48™, supports dual alarms, and logs timestamps during power-fail and power-restore events. It serves as a self-contained timing engine in resource-constrained embedded systems.
Does the MCP79401T-I/MNY require external load capacitors for the crystal?
Yes, the MCP79401T-I/MNY requires external load capacitors on X1 and X2 pins when using a 32.768 kHz crystal. It is optimized for crystals with 6–9 pF load capacitance; capacitor values must be selected to match the crystal's specified CL, accounting for PCB stray capacitance and on-die oscillator pin capacitance (3 pF typical).
How does the power-fail timestamp feature work in the MCP79401T-I/MNY?
The MCP79401T-I/MNY automatically logs the exact time of VCC dropout into PWRDNxxx registers and the time of VCC restoration into PWRUPxxx registers. This occurs during hardware-controlled switchover between VCC and VBAT (threshold 1.3–1.7 V), without host intervention - enabling forensic analysis of power events in energy meters and industrial controllers.
Can the MCP79401T-I/MNY operate solely from the VBAT supply?
No - the MCP79401T-I/MNY disables its I²C interface and EEPROM programming functions when operating from VBAT only. Timekeeping, SRAM retention, and alarm generation remain active, but register reads/writes and EEPROM access require VCC to be present. This prevents unintended writes during backup-only operation.
What is the significance of the EUI-48™ address in the MCP79401T-I/MNY?
The EUI-48™ address in the MCP79401T-I/MNY is a factory-programmed, globally unique 48-bit identifier stored in protected EEPROM. It enables plug-and-play network identity for IoT nodes and industrial devices without requiring external ID storage or firmware-based MAC assignment - simplifying certification, provisioning, and secure communication stack integration.
MCP79401T-I/MNY Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Alarm, Leap Year, Square Wave Output, SRAM, Unique ID
- Memory Size:
- 64B
- Time Format:
- HH:MM:SS (12/24 hr)
- Date Format:
- YY-MM-DD-dd
- Interface:
- I2C, 2-Wire Serial
- Voltage - Supply:
- 1.8V ~ 5.5V
- Voltage - Supply, Battery:
- 1.3V ~ 5.5V
- Current - Timekeeping (Max):
- 1.2µA (Typ) @ 3.3V
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 8-TDFN (2x3)
MCP79401T-I/MNY FAQ
1.How can I place an order for MCP79401T-I/MNY through Aetrix?
Please submit a Request for Quotation (RFQ) for MCP79401T-I/MNY on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MCP79401T-I/MNY reliable?
The price and inventory of MCP79401T-I/MNY are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MCP79401T-I/MNY is usually 5 days.
3.What payment methods are accepted for MCP79401T-I/MNY?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MCP79401T-I/MNY transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MCP79401T-I/MNY?
MCP79401T-I/MNY orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MCP79401T-I/MNY order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MCP79401T-I/MNY?
For technical support, including MCP79401T-I/MNY datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MCP79401T-I/MNY requirements.
6.How does Aetrix verify that MCP79401T-I/MNY is sourced from the original manufacturer or authorized distributors?
All MCP79401T-I/MNY products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MCP79401T-I/MNY meets industry standards.
7.What is the process for return or replacement of MCP79401T-I/MNY?
All MCP79401T-I/MNY units undergo pre-shipment inspection (PSI). If there is an issue with MCP79401T-I/MNY, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MCP79401T-I/MNY part is unused and in its original packaging.
Return procedure for MCP79401T-I/MNY:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MCP79401T-I/MNY Tags
-
MCP7940N-I/SN
Microchip Technology
-
MCP7940MT-I/MNY
Microchip Technology
-
PCF85063ATL/1,118
NXP USA Inc.
-
MCP7940NT-I/SN
Microchip Technology
-
MCP7940NT-I/MS
Microchip Technology
-
MCP7940N-I/MS
Microchip Technology
-
PCF85063AT/AY
NXP USA Inc.
-
PCF85063TP/1Z
NXP Semiconductors
-
PCF85063ATT/AJ
NXP USA Inc.
-
MCP7940NT-E/SN
Microchip Technology
-
MCP7940NT-I/MNY
Microchip Technology
-
MCP79400T-I/SN
Microchip Technology
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