PIC18LF2431-I/SO - 8-Bit 40MHz 16KB Flash MCU | Microchip
MPN: PIC18LF2431-I/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.45 | $5.45 |
| 10 | $4.91 | $49.10 |
| 100 | $4.15 | $415.00 |
| 500 | $3.6 | $1,800.00 |
| 1,000 | $3.1 | $3,100.00 |
PIC18LF2431-I/SO Overview
An 8-bit microcontroller (MCU) is a single-chip computer built around an 8-bit data path, integrating a CPU, RAM, non-volatile program memory, peripherals, and I/O on one die. 8-bit MCUs sit at the entry level of the microcontroller taxonomy - between fixed-function logic ICs and 32-bit Cortex-M microcontrollers - and remain dominant in cost-sensitive, deterministic control applications such as motor control, sensor interfaces, and appliance electronics. The PIC18 family in particular is known for its 77 single-word instruction set, 16-bit instructions, and on-chip peripherals like the enhanced Capture/Compare/PWM (ECCP) module that this part uses for power-conversion and motor-control loops.
The PIC18LF2431's headline features are the integrated 14-bit Enhanced Power Control PWM (with up to 6 PWM outputs), a 10-bit A/D converter with up to 9 channels, nanoWatt technology for power-managed idle/sleep modes, and an enhanced USART. The ECCP module provides hardware dead-band control, auto-shutdown, and complementary outputs - features that simplify half-bridge and full-bridge driver designs without software overhead.
Architecturally, the device uses a 16-bit instruction word with Harvard busing, an 8-bit data path, and a hardware multiplier (8x8 single-cycle). The 'LF' low-voltage silicon supports an extended VDD range down to 2.0V; this is the principal parametric difference from the PIC18F2431, which requires 4.2V minimum. Both parts share the same 28-SOIC pinout, allowing a one-line BOM swap when a design needs to migrate between the two voltage windows.
Typical applications include sensorless BLDC motor control (the integrated 14-bit PWM is purpose-built for this), switch-mode power supply (SMPS) digital control loops, industrial fan/pump controllers, and battery-powered sensor signal-conditioning front-ends. Industrial-grade (-40C to +85C) operation is preserved through the 'I' suffix in the part number.
Designers should note that the 28-SOIC variant is the right choice when 22 I/O pins suffice; the PIC18LF2431 family is also available in 40-pin PDIP and 44-pin TQFP packages if more I/O are needed. The nanoWatt modes (Idle, Sleep, and Timer1/RTCC oscillator) reduce quiescent current below 1 uA in typical Sleep conditions, which is the primary lever for extending battery life in portable designs.
This page synthesizes distributor pricing, drop-in package alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC18LF2431-I/SO — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with PIC18LF2431-I/SO (same form factor and footprint) — differing in Package, Core Architecture, Timers, Operating Temperature, ADC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F2431-I/SO
✅ Drop-In✓ In Stock
$4.85 / Unit
View Datasheet →PIC18LF2331-I/SO
✅ Drop-In✓ In Stock
$4.88 / Unit
View Datasheet →PIC18F2331-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF2431-I/SP
✅ Drop-In✓ In Stock
$4.4 / Unit
View Datasheet →PIC18LF2331-I/SP
✅ Drop-In✓ In Stock
$3.85 / Unit
View Datasheet →PIC18LF24K22-I/SO
✅ Drop-In✓ In Stock
$1.75 / Unit
View Datasheet →PIC18LF2431-I/SO Maximum Ratings & Electrical Characteristics
| Family | PIC18F |
| Core | 8-bit PIC |
| Maximum CPU Frequency | 40 MHz (10 MIPS) |
| Program Flash | 16 KB (8K x 16) |
| RAM | 768 bytes |
| EEPROM | 256 bytes |
| Supply Voltage (VDD) | 2.0 V to 5.5 V |
| I/O Pins | 22 |
| Package | 28-SOIC (7.50 mm wide) |
| A/D Converter | 10-bit, up to 9 channels |
| PWM Module | Enhanced 14-bit ECCP, up to 6 outputs |
| Communication | Enhanced USART, MSSP (SPI/I2C) |
| Timers | Timer0, Timer1, Timer2, Timer3 |
| Operating Temperature | -40C to +85C (Industrial) |
| Instruction Set | 77 single-word instructions, 16-bit wide |
| Hardware Multiplier | 8x8 single-cycle |
| Power-Saving Modes | nanoWatt (Idle, Sleep, Low-Power Timer1) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
PIC18LF2431-I/SO Pin Configuration
| Pin 1 | MCLR/VPP/RE3 — Master clear reset (active low) / programming voltage / digital input only on RE3 |
| Pin 2 | RA0/AN0 — PORTA bit 0 / analog input channel 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / analog input channel 1 |
| Pin 4 | RA2/AN2/VREF- — PORTA bit 2 / analog input 2 / ADC VREF- |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / analog input 3 / ADC VREF+ |
| Pin 6 | RA4/AN4/T0CKI — PORTA bit 4 (open-drain) / analog input 4 / Timer0 clock input |
| Pin 7 | RA5/AN5/SS/LVDIN — PORTA bit 5 / analog input 5 / SPI slave select / LVD input |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKI/RA7 — Crystal oscillator input / external clock input / PORTA bit 7 |
| Pin 10 | OSC2/CLKO/RA6 — Crystal oscillator output / clock output / PORTA bit 6 |
| Pin 11 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 12 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 PWM output |
| Pin 13 | RC2/CCP1 — PORTC bit 2 / CCP1 PWM output |
| Pin 14 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 15 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 16 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 17 | RC6/TX/CK — PORTC bit 6 / USART TX / USART synchronous clock |
| Pin 18 | RC7/RX/DT — PORTC bit 7 / USART RX / USART synchronous data |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage (2.0V to 5.5V for LF variant) |
| Pin 21 | RB0/INT0 — PORTB bit 0 / external interrupt 0 |
| Pin 22 | RB1/INT1 — PORTB bit 1 / external interrupt 1 |
| Pin 23 | RB2/INT2 — PORTB bit 2 / external interrupt 2 |
| Pin 24 | RB3/CCP2 — PORTB bit 3 / CCP2 PWM output (alternate) |
| Pin 25 | RB4 — PORTB bit 4 (interrupt-on-change) |
| Pin 26 | RB5 — PORTB bit 5 (interrupt-on-change) |
| Pin 27 | RB6/PGC — PORTB bit 6 / ICSP clock / interrupt-on-change |
| Pin 28 | RB7/PGD — PORTB bit 7 / ICSP data / interrupt-on-change |
Typical Applications
PIC18LF2431-I/SO is suitable for 6 applications: Sensorless BLDC Motor Control, Switch-Mode Power Supply (SMPS) Digital Control, Industrial Fan / Pump Variable-Speed Controller, Battery-Powered Sensor Signal Conditioning, Appliance Control Board (Washer / Dryer / Dishwasher), Automotive Auxiliary Motor / Pump Controller.
Sensorless BLDC Motor Control
The PIC18LF2431-I/SO is purpose-built for sensorless BLDC motor control. Its integrated 14-bit Enhanced Power Control PWM module provides up to 6 PWM outputs with hardware dead-band, auto-shutdown, and complementary pairing - eliminating software overhead for half-bridge and full-bridge FET drive. The 10-bit ADC with up to 9 channels reads back-EMF zero-crossing events to detect rotor position without Hall sensors. The 2.0V-5.5V VDD range allows direct operation from a Li-ion or 2x-3xAA pack, while nanoWatt idle modes drop quiescent current below 1 uA between commutation cycles. At 40 MHz (10 MIPS), the core executes a full sensorless commutation loop with back-EMF sampling, PI speed control, and PWM update well inside one PWM period. Designers place 10 nF ceramic bypass caps within 5 mm of VDD/VSS, route PWM outputs in matched-length pairs to the gate driver, and use the ECCP auto-shutdown input tied to the DC-bus current-sense comparator for hardware overcurrent protection.
Recommended
Switch-Mode Power Supply (SMPS) Digital Control
The PIC18LF2431-I/SO serves as a low-cost digital controller for isolated and non-isolated SMPS topologies including flyback, forward, and PFC boost. The 14-bit ECCP PWM provides resolution sufficient for duty-cycle control at 100 kHz-200 kHz switching frequencies, while the enhanced USART handles PMBus or UART telemetry. The 10-bit ADC samples output voltage, input voltage, and primary current for closed-loop regulation. With 16 KB Flash and 768 bytes RAM, firmware can include a 2-pole/2-zero digital compensator, soft-start, and brown-out recovery. The 2.0V-5.5V VDD range enables direct bias from an auxiliary 5V rail or Li-ion supply, while nanoWatt Sleep mode cuts standby power below 50 uA for ENERGY STAR compliance. Typical design tips: use the Timer2/4 high-speed PWM mode for fixed-frequency control, route the current-sense signal directly to the ADC with an RC anti-alias filter, and use the ECCP auto-shutdown pin to latch the gate drive low on overcurrent.
Recommended
Industrial Fan / Pump Variable-Speed Controller
The PIC18LF2431-I/SO is a strong fit for industrial fan and pump VFD controllers where 22 I/O pins and ECCP PWM are sufficient. The 14-bit PWM drives a 3-phase IGBT or MOSFET bridge via gate drivers, while the 10-bit ADC reads motor current, bus voltage, and NTC thermistor for thermal foldback. The 2.0V-5.5V VDD range allows direct operation from 24V industrial bus through a small buck regulator. Industrial-grade -40C to +85C operation (denoted by the 'I' suffix) covers HVAC and factory-floor deployment. nanoWatt idle/sleep modes drop standby consumption below 100 uA, important for ERP-compliant energy ratings. The 768-byte RAM holds a sensorless observer or simple V/Hz table plus fault log. The MSSP peripheral provides I2C/SPI for an external display or EEPROM, and the enhanced USART implements RS-485 Modbus for industrial networking.
Recommended
Battery-Powered Sensor Signal Conditioning
The PIC18LF2431-I/SO operates down to 2.0 V, making it ideal for battery-powered sensor signal conditioning front-ends powered directly from 2xAA or 3xAA alkaline / NiMH cells, or a single Li-ion cell in discharge. The 10-bit ADC with up to 9 channels digitizes thermocouple, RTD, or strain-gauge signals after external op-amp conditioning; the 16 KB Flash holds linearization tables, polynomial correction, and EEPROM-backed calibration. nanoWatt Sleep mode drops current below 1 uA between samples, allowing multi-year battery life on a duty-cycled 1-Hz sample rate. The enhanced USART streams readings over UART or wireless link; MSSP handles I2C sensor expansion. Designers typically route the ADC reference pin to a low-drift 2.5V external reference (e.g. MCP1525) for absolute accuracy, use the internal RC oscillator to minimize part count, and wake from Sleep via Timer1 interrupt.
Recommended
Appliance Control Board (Washer / Dryer / Dishwasher)
The PIC18LF2431-I/SO integrates the motor-control and user-interface logic for cost-sensitive white-goods control boards. The 14-bit ECCP PWM drives the main motor via a 3-phase inverter; the 10-bit ADC reads water level, temperature, and motor current; the enhanced USART links to a display panel or wireless module. The 22 I/O pins handle keypad, LED indicators, buzzer, door switch, and triac-fired heater/valve control. The 2.0V-5.5V range supports both 3.3 V logic and 5 V relay/triac drive. Industrial-grade -40C to +85C operation covers under-cabinet and basement deployments. nanoWatt idle is used in standby. The 16 KB Flash holds wash-cycle state machines and diagnostic fault logs. The MSSP peripheral supports an external I2C EEPROM for cycle counters.
Recommended
Automotive Auxiliary Motor / Pump Controller
The PIC18LF2431-I/SO is used in non-safety automotive auxiliary loads such as seat-cooling fans, water pumps, oil pumps, and HVAC blend-door actuators where AEC-Q100 is not mandatory. The 14-bit ECCP PWM drives the BLDC or brushed-DC motor; the 10-bit ADC reads current and temperature; the enhanced USART or LIN-friendly MSSP handles comms. The 2.0V-5.5V range survives cold-cranking and load-dump transients when paired with a TVS-protected 12V-to-5V regulator. Industrial-grade -40C to +85C covers cabin deployment; under-hood designs need AEC-Q100 parts (e.g. PIC18F2431-I/SO family extended temp variants). nanoWatt idle is essential for parked-vehicle quiescent current targets below 100 uA. The 16 KB Flash holds torque maps and fault diagnostics.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF2431-I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F2431-I/SO | PIC18LF2331-I/SO | PIC18F2331-I/SO | PIC18LF2431-I/SP | PIC18LF2331-I/SP | PIC18LF24K22-I/SO |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC | 28-SOIC - same | 28-SOIC - same | 28-SOIC - same | 28-SPDIP - through-hole equivalent | 28-SPDIP - through-hole equivalent | 28-SOIC - same |
| Program Flash | 16 KB | 16 KB | 8 KB (-50%) | 8 KB (-50%) | 16 KB | 8 KB (-50%) | 16 KB |
| RAM | 768 bytes | 768 bytes | 768 bytes | 768 bytes | 768 bytes | 768 bytes | 1024 bytes (+33%) |
| VDD Range | 2.0 V to 5.5 V | 4.2 V to 5.5 V | 2.0 V to 5.5 V | 4.2 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 1.8 V to 5.5 V |
| CPU Frequency | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 64 MHz / 16 MIPS |
| ECCP PWM | 14-bit, 6 outputs | 14-bit, 6 outputs | 14-bit, 6 outputs | 14-bit, 6 outputs | 14-bit, 6 outputs | 14-bit, 6 outputs | 10-bit CCP, 5 PWM channels |
| I/O Pins | 22 | 22 | 22 | 22 | 22 | 22 | 25 |
| Unit Price (qty 100) | $4.15 | $3.60 (-13%) | $3.40 (-18%) | $3.20 (-23%) | $4.30 (+4%) | $3.60 (-13%) | $2.90 (-30%) |
Key Differentiators
- Low-voltage 2.0V VDD operation (vs PIC18F2431-I/SO)
- Integrated 14-bit ECCP with 6 PWM outputs (vs PIC18LF24K22-I/SO)
- Larger 16 KB Flash vs 8 KB family members (vs PIC18LF2331-I/SO)
Design Notes
Place a 100 nF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 20) and a 10 uF bulk capacitor on the board's VDD plane. The PIC18LF2431-I/SO's nanoWatt Sleep mode draws less than 1 uA typical at 3 V, but during ADC conversions the AVDD line can draw 200-400 uA - decouple AVDD separately if used. Use the internal 31 kHz LFINTOSC for sleep cycling to minimize active current; switch to the 16 MHz HFINTOSC + PLL only for the ADC conversion window.
Do not apply VDD below 2.0 V on the LF variant or below 4.2 V on the standard F variant - either causes brown-out reset and possible Flash corruption. Configure the BOR (Brown-Out Reset) module in configuration words to the lowest voltage the application allows (typically 2.0V for LF designs). When migrating from PIC18F2431 to PIC18LF2431, verify that the BOR voltage and PWRT settings are re-flashed, otherwise the part may not start at 3.3 V.
Route the ECCP PWM outputs (RC1/RC2 and RB3) as matched-length differential pairs (within 2 mm) to minimize skew in 3-phase motor-drive timing. Keep analog inputs (RA0-RA5) away from PWM switching traces - a 4-layer board with a solid ground plane below the analog traces is recommended. Place the crystal (if used) within 10 mm of OSC1/OSC2 with a guard ring tied to ground. MCLR requires a 10 kohm pull-up and a 100 nF cap to ground for in-circuit serial programming (ICSP).
The 28-SOIC package has a thermal resistance (theta_JA) of approximately 80 C/W in still air. At maximum CPU activity (40 MHz, peripherals on), the internal die dissipation is well below 100 mW - no heatsink is required. In high-ambient (>60C) industrial enclosures, however, derate CPU frequency to 32 MHz to keep junction temperature below 125C. Use the internal temperature indicator diode (if available via MSSP) to monitor die temperature in safety-critical applications.
Compliance Information
RoHS compliant per Microchip product page. Industrial temperature grade -40C to +85C denoted by 'I' suffix. Not AEC-Q100 qualified - choose AEC-Q100 PIC variants for automotive.
