MCP7940N-I/SN

• I = Industrial temperature grade
• SN = 8-pin narrow SOIC surface-mount package

1. Core Timekeeping Functions

• Full calendar tracking: Second, Minute, Hour, Weekday, Date, Month, Year
• Auto leap-year compensation valid up to year 2399; auto-adjust for months with less than 31 days
• Support both 12-hour AM/PM and 24-hour time format
• Designed for standard 32.768 kHz tuning fork crystal oscillator (6–9 pF load capacitance)
• On-chip digital frequency trimming: 1 ppm adjustment resolution, ±129 ppm full calibration range for high clock accuracyMicrochip Technology

2. Alarm & Multi-Function Output

• Dual independent programmable alarms, configurable with second/minute/hour/day/month match conditions
• Single open-drain multi-function pin (MFP) with 3 working modes:
  1. Alarm interrupt trigger output
  2. Programmable square-wave clock output (4 selectable frequencies: 1 Hz, 4.096 kHz, 8.192 kHz, 32.768 kHz)
  3. General-purpose logic output for external control

3. Power Backup & Power-Fail Timestamp

• Automatic power switchover between main VCC supply and VBAT backup battery
• Main operating voltage: 1.8 V ~ 5.5 V; backup battery voltage: 1.3 V ~ 5.5 V
• Ultra-low timekeeping current under battery backup: typical 925 nA at 3.0 V VBAT
• Built-in power-fail timestamp register: automatically logs exact time when main power drops out and recovers
• All RTC registers and internal SRAM retain data during main power loss

4. On-Chip User SRAM & I²C Communication

• 64 bytes battery-backed SRAM for storing calibration parameters, log data or device settings
• I²C two-wire serial bus, compatible with 100 kHz standard and 400 kHz fast modes
• Fixed I²C slave address: Write 0x6F, Read 0x70, no address pin required
• High ESD protection (≥4 kV) on all I²C signal pins for industrial wiring noise immunity

5. Electrical & Environmental Ratings

• Operating temperature range (Industrial Grade I): -40°C to +85°C
• MSL 3 moisture sensitivity level (168-hour floor life before reflow soldering)
• Fully RoHS lead-free and halogen-free compliant
• Standard tube packaging; tape-and-reel variant MCP7940NT-I/SN available for mass SMT production

6. Package Information

• Package: 8-pin narrow-body SOIC (3.9 mm width compact SMD footprint)
• Pin definition: VCC, SDA, SCL, MFP, VSS, VBAT, X2, X1 for crystal connection

Typical Applications

• Industrial data loggers, energy meters and PLC control panels with timestamp recording
• Smart home / IoT wireless sensor nodes with battery-powered timekeeping
• Portable handheld test & measurement instruments
• Digital signage, network switches and embedded gateway time synchronization
• Household appliances (refrigerators, washing machines, HVAC controllers)
• Low-power battery monitoring systems and environmental monitoring equipment
• Automotive infotainment, telematics and dashboard timing modules
• Embedded development boards with real-time clock expansion function