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Microchip Technology MCP7940N-E/MS
- Part No.:
- MCP7940N-E/MS
- Manufacturer:
- Microchip Technology
- Category:
- Real Time Clocks
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MCP7940N-E/MS.pdf
- Description:
- IC RTC CLK/CALENDAR I2C 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:603
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Product details
Overview
MCP7940N-E/MS from Microchip Technology is a battery-backed I²C Real-Time Clock/Calendar (RTCC) IC with integrated 64-byte SRAM, digital trimming, dual alarms, and power-fail time-stamping. It operates from 1.8V–5.5V, consumes 1.2 µA at 3.3V during timekeeping, and supports 32.768 kHz crystal oscillation with ±1 ppm trimming resolution. It is used in industrial control panels requiring accurate timestamping of power-loss events.
For engineers reviewing the MCP7940N-E/MS datasheet, MCP7940N-E/MS pinout, MCP7940N-E/MS application, or MCP7940N-E/MS equivalent, this page delivers verified technical context, package-specific pin mapping, real-world use scenarios, and validated alternative parts for time-critical embedded systems design.
Technical Context
The MCP7940N-E/MS implements a fully autonomous RTCC using BCD-encoded time registers (seconds to year), leap-year compensation through 2399, and automatic rollover handling across date/month boundaries. Its oscillator circuit supports both external 32.768 kHz crystals (optimized for 6–9 pF load) and external clock inputs via X1, with OSCRUN status flag and TOSF timeout detection.
Power management includes seamless switchover between VCC and VBAT (1.3–5.5V), logging timestamps at both power-down and power-up transitions. The MFP pin serves as configurable open-drain output for alarm assertion, selectable square-wave generation (32.768 kHz, 1024 Hz, 32 Hz, 1 Hz), or general-purpose signaling - all controlled via the CONTROL register.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Timekeeping Accuracy | ±1 ppm digital trimming resolution over ±129 ppm range enables fine-tuning against crystal tolerance and temperature drift. |
| I²C Interface Speed | Up to 400 kHz (at VCC ≥ 2.5V); ensures fast register access without bus contention in multi-device systems. |
| Backup Current | 925 nA typical at 3.0V VBAT - sustains >10 years on CR1220 coin cell while preserving time and SRAM data. |
| Operating Temp Range | –40°C to +125°C (Extended grade) - qualified for under-hood automotive and high-temperature industrial environments. |
| Crystal Load Range | Optimized for 6–9 pF crystals - reduces need for iterative capacitor selection during layout validation. |
| Alarm Capability | Dual independent alarms with maskable fields (second to month) - enables precise event scheduling without host CPU polling. |
| SRAM Size | 64 bytes of battery-backed SRAM - stores calibration data, configuration flags, or last-known state across power cycles. |
Pinout & Package
Package: 8-Lead MSOP (3.0 mm × 3.0 mm, 0.65 mm pitch), exposed pad optional to VSS. Pinout matches MSOP variant per DS20005010J-page 8.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| X1 | Crystal input / External clock input | Accepts 32.768 kHz crystal or external oscillator signal; also used for digital trimming calibration reference. |
| X2 | Crystal output | Drives crystal resonator; must be left floating when external clock mode is enabled (EXTOSC = 1). |
| VBAT | Backup supply input | Provides continuous power to RTCC and SRAM during main supply loss; valid from 1.3V to 5.5V. |
| VSS | Ground reference | System ground return path; exposed pad on MSOP may be tied to VSS for thermal and noise performance. |
| SDA | I²C bidirectional data line | Open-drain interface requiring external pull-up; supports standard/fast-mode I²C up to 400 kHz. |
| SCL | I²C clock input | Host-generated clock synchronizing all register reads/writes and SRAM access. |
| MFP | Multi-function open-drain output | Configurable as alarm pulse, programmable square wave (4 frequencies), or GPIO - no internal pull-up. |
| VCC | Main power supply | Primary operating voltage (1.8V–5.5V); powers logic, I²C interface, and oscillator; triggers switchover at VTRIP (1.3–1.7V). |
Key Features
| Feature | Design Value |
|---|---|
| Power-fail time-stamping | Automatically logs exact time of VCC dropout and restoration into dedicated PWRDN/PWRUP registers - eliminates need for external supervision circuitry. |
| Digital trimming engine | ±129 ppm adjustment range with ±1 ppm step size - corrects for crystal aging and board-level parasitics without hardware changes. |
| Dual independent alarms | Each alarm masks seconds through month fields individually - enables one-shot or repeating triggers (e.g., daily log flush at 02:00 AM). |
| BCD time register buffering | Hardware-buffered read of 0x00–0x1F addresses prevents rollover corruption - guarantees atomic time snapshot even during second boundary. |
| Extended temperature grade | AEC-Q100 qualified and rated –40°C to +125°C - validated for automotive infotainment, telematics, and industrial PLC applications. |
Applications
| Industrial Control Panel | Smart Energy Meter |
|---|---|
|
Use Scenario: Timestamping of equipment fault events and maintenance intervals in factory HMIs. IC Role / Device Role / Timing Role: Primary RTCC providing wall-clock time, calendar date, and power-loss recovery logging. Use Value: Maintains accurate time across brownouts using VBAT; power-fail stamps enable root-cause analysis of downtime duration. |
Use Scenario: Recording energy consumption intervals and tariff-switching events in utility-grade meters. IC Role / Device Role / Timing Role: Time source synchronized to grid frequency; triggers data capture at fixed intervals (e.g., every 15 minutes). Use Value: Dual alarms schedule meter reads and firmware updates; 64-byte SRAM stores billing cycle counters and tamper logs. |
| Automotive Telematics Unit | Medical Infusion Pump |
|
Use Scenario: Logging GPS position timestamps and diagnostic trouble codes (DTCs) during vehicle operation. IC Role / Device Role / Timing Role: Extended-temp RTCC ensuring time integrity in under-dash environments (-40°C to +125°C). Use Value: AEC-Q100 qualification and backup current <1 µA support long-term reliability and battery life in always-on modules. |
Use Scenario: Auditing drug delivery timing and operator intervention events in critical-care infusion systems. IC Role / Device Role / Timing Role: Fail-safe timekeeper retaining calibrated dosing schedules and audit trail during AC power interruption. Use Value: Battery-backed SRAM preserves therapy parameters; power-fail stamps verify compliance with FDA 21 CFR Part 11 electronic record requirements. |
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 |
|---|---|---|---|
| MCP7941M-E/MS | Same pinout and register map; adds EEPROM (128 bytes) and enhanced alarm masking (including weekday-only triggers). | Preferred where firmware update history or extended nonvolatile parameter storage is required beyond 64-byte SRAM. | Select MCP7941M-E/MS if EEPROM-based configuration persistence or finer alarm granularity is needed. |
| DS3231SN#T&R | Integrated TCXO (±2 ppm accuracy); higher timekeeping current (3 µA typ); no user SRAM; different I²C address (0x68 vs 0x6F). | Better suited for ultra-high-accuracy applications (e.g., precision instrumentation) where temperature-induced drift must be minimized. | Choose DS3231SN#T&R only when absolute accuracy outweighs power budget and SRAM requirements. |
Compared with MCP7940N-E/MS, MCP7941M-E/MS extends functionality without layout change, while DS3231SN#T&R trades SRAM and low-power advantage for superior oscillator stability - making each suitable for distinct system-level trade-offs.
Availability
MCP7940N-E/MS is available at Aetrix Electronics and suitable for industrial control panels, smart energy meters, automotive telematics units, and medical infusion pumps requiring stable component supply across extended temperature and long-life deployments.
Supply support for MCP7940N-E/MS 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 devices, and timing solutions, serving automotive, industrial, and consumer markets with high-reliability silicon and development tools.
The MCP7940N product line delivers highly integrated, battery-backed RTC/Calendar ICs designed for applications demanding accurate timekeeping, low-power backup operation, and robust power-fail event logging - especially where extended temperature and AEC-Q100 compliance are critical.
FAQ
What is the primary function of the MCP7940N-E/MS?
The MCP7940N-E/MS is a battery-backed I²C Real-Time Clock/Calendar IC that maintains accurate time and date (seconds to year), supports dual programmable alarms, provides 64-byte SRAM, and logs timestamps during power-fail and power-up events. It operates across –40°C to +125°C and is AEC-Q100 qualified for automotive and industrial use.
Does the MCP7940N-E/MS require external load capacitors for its crystal oscillator?
Yes, the MCP7940N-E/MS requires external load capacitors on X1 and X2 pins when using a 32.768 kHz tuning fork 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 per Equation 5-1 in the datasheet.
How does the MCP7940N-E/MS handle power switchover between VCC and VBAT?
The MCP7940N-E/MS automatically switches to VBAT when VCC drops below the switchover threshold (1.3–1.7V). During switchover, it logs the exact time into dedicated PWRDN registers; upon VCC restoration, it records the time in PWRUP registers. Both RTCC and SRAM retain data throughout the transition.
Can the MFP pin on the MCP7940N-E/MS generate multiple square-wave frequencies?
Yes, the MFP pin on the MCP7940N-E/MS can output four selectable square-wave frequencies: 32.768 kHz, 1024 Hz, 32 Hz, or 1 Hz - configured via SQWFS[1:0] bits in the CONTROL register. It operates as an open-drain output and requires an external pull-up resistor to VCC.
Is the MCP7940N-E/MS compatible with standard I²C protocols and addressing?
Yes, the MCP7940N-E/MS uses a fixed 7-bit I²C client address of 0x6F (1101111x) and supports standard-mode (100 kHz) and fast-mode (400 kHz) I²C communication. It implements full START/STOP, ACK/NACK, and data validity timing per I²C specification, with SDA and SCL featuring Schmitt-trigger inputs.
MCP7940N-E/MS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Clock/Calendar
- Features:
- Alarm, Leap Year, Square Wave Output, SRAM
- 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 @ 3.3V
- Operating Temperature:
- -40°C ~ 125°C
- Mounting Type:
- Surface Mount
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Supplier Device Package:
- 8-MSOP
MCP7940N-E/MS FAQ
1.How can I place an order for MCP7940N-E/MS through Aetrix?
Please submit a Request for Quotation (RFQ) for MCP7940N-E/MS 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 MCP7940N-E/MS reliable?
The price and inventory of MCP7940N-E/MS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MCP7940N-E/MS is usually 5 days.
3.What payment methods are accepted for MCP7940N-E/MS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MCP7940N-E/MS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MCP7940N-E/MS?
MCP7940N-E/MS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MCP7940N-E/MS 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 MCP7940N-E/MS?
For technical support, including MCP7940N-E/MS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MCP7940N-E/MS requirements.
6.How does Aetrix verify that MCP7940N-E/MS is sourced from the original manufacturer or authorized distributors?
All MCP7940N-E/MS 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 MCP7940N-E/MS meets industry standards.
7.What is the process for return or replacement of MCP7940N-E/MS?
All MCP7940N-E/MS units undergo pre-shipment inspection (PSI). If there is an issue with MCP7940N-E/MS, 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 MCP7940N-E/MS part is unused and in its original packaging.
Return procedure for MCP7940N-E/MS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MCP7940N-E/MS 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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