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MCP79400T-I

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Microchip Tech Real Time Clocks, SOIC-8. Pinout cross-checked by two models against the datasheet, KiCad symbol/footprint/3D.

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MCP79400T-I

Microchip Tech · Real Time Clocks · SOIC-8

MCP79400T-I from Microchip Tech, in a SOIC-8. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin Name Type Function
1 X1 input Crystal oscillator input for a 32.768 kHz tuning-fork crystal with external load capacitors, optimized for crystals with 6-9 pF load capacitance; it also serves as the external clock input when the device is configured for an external oscillator.
2 X2 output Crystal oscillator output for the 32.768 kHz crystal; it must be left floating when an external 32.768 kHz clock is applied to X1.
3 VBAT power_in Backup supply input that maintains the RTCC and SRAM when VCC is unavailable; connect to VSS if battery backup is not used.
4 VSS power_in Ground reference for the device.
5 SDA bidirectional Open-drain bidirectional I2C serial data line that requires a pull-up resistor to VCC (typically 10 kΩ for 100 kHz or 2 kΩ for 400 kHz), and may change only while SCL is low except for Start and Stop conditions.
6 SCL input I2C serial clock input that synchronizes data transfer to and from the device.
7 MFP output Open-drain multifunction output for alarm, square-wave, or general-purpose output that requires a pull-up resistor to VCC (typically 10 kΩ) and may be left floating if unused.
8 VCC power_in Primary power supply input, with an operating voltage range of 1.8 V to 5.5 V as stated in the datasheet features list.

Key specifications

Parameter Value
Manufacturer Microchip Tech
Package SOIC-8
Category Clock/Timing
Pins 8

Electrical characteristics

Limits as printed in the datasheet (page.json metadata.characteristics carries them as data).

Parameter Symbol Min Typ Max Unit Conditions Page
Supply voltage (VCC) absolute maximum VCC 6.5 V 3
All inputs and outputs (except SDA and SCL) w.r.t. VSS -0.6 V 3
SDA and SCL w.r.t. VSS -0.6 6.5 V 3
Storage temperature -65 150 °C 3
Ambient temperature with power applied -40 125 °C 3
ESD protection on all pins 4 kV 3
Operating supply voltage range (Industrial) VCC 1.8 5.5 V Industrial (I) 3
Operating ambient temperature range (Industrial) TA -40 85 °C Industrial (I) 3
High-level input voltage (SDA, SCL) VIH 0.7 ×VCC 3
Low-level input voltage (SDA, SCL) VIL 0.3 ×VCC VCC ≥ 2.5V 3
Low-level input voltage (SDA, SCL) VIL 0.2 ×VCC VCC < 2.5V 3
Hysteresis of Schmitt trigger inputs (SDA, SCL) VHYS 0.05 ×VCC Note 1 3
Low-level output voltage (MFP, SDA) VOL 0.4 V IOL = 3.0 mA; VCC = 4.5V 3
Input leakage current ILI -1 1 µA VIN = VSS or VCC 3
Output leakage current ILO -1 1 µA VOUT = VSS or VCC 3
Pin capacitance (SDA, SCL, MFP) CIN, COUT 10 pF VCC = 5.0V (Note 1); TA = 25°C, f = 1 MHz 3
EEPROM operating current (read) ICCEERD 400 µA VCC = 5.5V, SCL = 400 kHz 3
EEPROM operating current (write) ICCEEWR 3 mA VCC = 5.5V 3
SRAM/RTCC register operating current (read) ICCREAD 300 µA VCC = 5.5V, SCL = 400 kHz 3
SRAM/RTCC register operating current (write) ICCWRITE 400 µA VCC = 5.5V, SCL = 400 kHz 3
VCC data-retention current (oscillator off) ICCDAT 1 µA SCL, SDA, VCC = 5.5V 3
Power-fail switchover voltage VTRIP 1.3 1.5 1.7 V 3
Backup supply voltage range VBAT 1.3 5.5 V Note 1 3
Timekeeping backup current IBATT 850 nA VBAT = 1.3V, VCC = VSS (Note 1) 4
Timekeeping backup current IBATT 925 1200 nA VBAT = 3.0V, VCC = VSS (Note 1) 4
Timekeeping backup current IBATT 9000 nA VBAT = 5.5V, VCC = VSS (Note 1) 4
VBAT data-retention current (oscillator off) IBATDAT 750 nA VBAT = 3.6V, VCC = VSS 4
Clock frequency FCLK 100 kHz 1.8V ≤ VCC < 2.5V 5
Clock frequency FCLK 400 kHz 2.5V ≤ VCC ≤ 5.5V 5
Clock high time THIGH 4000 ns 1.8V ≤ VCC < 2.5V 5
Clock high time THIGH 600 ns 2.5V ≤ VCC ≤ 5.5V 5
Clock low time TLOW 4700 ns 1.8V ≤ VCC < 2.5V 5
Clock low time TLOW 1300 ns 2.5V ≤ VCC ≤ 5.5V 5
SDA and SCL rise time (Note 1) TR 1000 ns 1.8V ≤ VCC < 2.5V 5
SDA and SCL rise time (Note 1) TR 300 ns 2.5V ≤ VCC ≤ 5.5V 5
SDA and SCL fall time (Note 1) TF 1000 ns 1.8V ≤ VCC < 2.5V 5
SDA and SCL fall time (Note 1) TF 300 ns 2.5V ≤ VCC ≤ 5.5V 5
Start condition hold time THD:STA 4000 ns 1.8V ≤ VCC < 2.5V 5
Start condition hold time THD:STA 600 ns 2.5V ≤ VCC ≤ 5.5V 5
Start condition setup time TSU:STA 4700 ns 1.8V ≤ VCC < 2.5V 5
Start condition setup time TSU:STA 600 ns 2.5V ≤ VCC ≤ 5.5V 5
Data input hold time THD:DAT 0 ns Note 2 5
Data input setup time TSU:DAT 250 ns 1.8V ≤ VCC < 2.5V 5
Data input setup time TSU:DAT 100 ns 2.5V ≤ VCC ≤ 5.5V 5
Stop condition setup time TSU:STO 4000 ns 1.8V ≤ VCC < 2.5V 5
Stop condition setup time TSU:STO 600 ns 2.5V ≤ VCC ≤ 5.5V 5
Output valid from clock TAA 3500 ns 1.8V ≤ VCC < 2.5V 5
Output valid from clock TAA 900 ns 2.5V ≤ VCC ≤ 5.5V 5
Bus free time TBUF 4700 ns 1.8V ≤ VCC < 2.5V 5
Bus free time TBUF 1300 ns 2.5V ≤ VCC ≤ 5.5V 5
Input filter spike suppression (SDA and SCL) TSP 50 ns Note 1 5
Write cycle time (byte or page) TWC 5 ms 5
VCC fall time (Note 1) TFVCC 300 µs Note 1 5
VCC rise time (Note 1) TRVCC 0 µs Note 1 5
Oscillator timeout period (Note 1) TOSF 1 ms Note 1 5
Pin capacitance (X1, X2 oscillator pins) COSC 3 pF Note 1 3
Timekeeping current ICCT 1.2 µA VCC = 3.3V (Note 1) 3
Oscillator frequency FOSC 32.768 kHz 5

Materials and finish

As the datasheet states them (page.json metadata.appearance; the 3D model's colours follow it).

Part Material Colour / plating Datasheet says Page
contacts tin 8-Lead Plastic Small Outline (SN) - Narrow, 3.90 mm (.150 In.) Body [SOIC] A A2 44

CAD (KiCad official)

  • Symbol: MCP79400T-I
  • Footprint: Package_SO:SOIC-8_3.9x4.9mm_P1.27mm
  • 3D model: SOIC-8 (KiCad packages3D, STEP)
  • 3D model files: mcp79400t-i-etched.step / mcp79400t-i-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); mcp79400t-i.step / mcp79400t-i.glb are the bare package body.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: Microchip Tech datasheet (60 pp, sha256 9dbb557d73a1b0be, retrieved 2026-10-21, tier: lcsc)
  • Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-haiku-5-5 (text), consensus claude-sonnet-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF