PIC18F2431-I/SP - 8-bit MCU, 16KB Flash, 40MHz, Motor Control PWM | Microchip
MPN: PIC18F2431-I/SP ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.62 | $8.62 |
| 10 | $7.74 | $77.40 |
| 100 | $6.86 | $686.00 |
| 500 | $6.14 | $3,070.00 |
| 1,000 | $5.49 | $5,490.00 |
PIC18F2431-I/SP Overview
An 8-bit microcontroller (MCU) is a single-chip computer built around an 8-bit data path that executes instructions fetched from on-chip program memory. PIC microcontrollers use a RISC architecture with a single accumulator (WREG) and a Harvard memory structure, placing them in the broader category of microcontrollers -> embedded processors -> semiconductors. The PIC18 family is Microchip's mid-to-high-performance 8-bit line, distinguished from the PIC16 line by 16-bit opcodes, a wider instruction set, and richer peripheral integration for closed-loop control.
Key features of the PIC18F2431 include 25 I/O ports, three 16-bit timer/counters, dual analog comparators, a 10-bit ADC with up to 8 input channels, and nanoWatt power management for reduced sleep current. The integrated Power Control PWM module supports complementary outputs with programmable dead-band and hardware fault inputs, which simplifies three-phase motor drive design. The Motion Feedback Module captures quadrature encoder signals in hardware, offloading speed and position calculation from the CPU.
Typical applications include sensorless and sensored BLDC motor drives, AC induction motor control, switched-mode power supplies with digital PFC, and industrial automation where deterministic PWM timing is required. The wide operating range of -40C to +85C (industrial) and LIN support suit automotive body and convenience subsystems as well as white goods.
When designing with this device, pay close attention to the PWM output mapping and dead-band configuration - the PIC18F2431 and PIC18F4431 share the same peripheral set but differ in pin count (28-pin vs 44-pin). Place a 100 nF decoupling capacitor adjacent to each VDD/VSS pair and follow Microchip AN1078 for sensorless BLDC reference firmware.
This page synthesizes distributor pricing, drop-in alternative MPNs from the same PIC18F2x/4x family, and practical design notes not collected in the manufacturer datasheet.
Drop-in alternatives for PIC18F2431-I/SP — 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 PIC18F2431-I/SP (same form factor and footprint) — differing in Package, I/O Pins, ADC, Core Architecture, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F2331-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2431-I/SO
✅ Drop-In✓ In Stock
$4.85 / Unit
View Datasheet →PIC18F2431-E/SP
✅ Drop-In✓ In Stock
$3.91 / Unit
View Datasheet →PIC18F4331-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F242-I/SP
✅ Drop-In✓ In Stock
$5.3 / Unit
View Datasheet →PIC18F2431-I/SP Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit Microcontroller (MCU) |
| Family | PIC18F |
| Program Memory Size | 16 KB Flash (8K x 16) |
| RAM Size | 768 bytes |
| Maximum CPU Speed | 40 MHz |
| Supply Voltage Range | 4.2 V to 5.5 V |
| I/O Pins | 25 |
| Package | 28-pin SPDIP (Skinny Plastic DIP, 0.300 inch) |
| Mounting Type | Through-Hole |
| PWM Channels | 8 (Power Control PWM Module) |
| ADC | 10-bit, up to 200 ksps |
| Quadrature Encoder Interface | Yes (Motion Feedback Module) |
| Internal Oscillator | 8 MHz |
| Communication | LIN-capable USART |
| Self-Programming | Yes |
| Operating Temperature Range | -40C to +85C (Industrial) |
| RoHS Status | Compliant |
PIC18F2431-I/SP Pin Configuration
| Pin 1 | MCLR/RE3 — Master Clear (reset) input or digital input only |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input 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/TOCKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4 — PORTA bit 5 / Analog input 4 |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKI/RA7 — Crystal oscillator input / external clock |
| Pin 10 | OSC2/CLKO/RA6 — Crystal oscillator output |
| Pin 11 | RC0/T1OSO — PORTC bit 0 / Timer1 oscillator output |
| Pin 12 | RC1/T1OSI — PORTC bit 1 / Timer1 oscillator input |
| Pin 13 | RC2/CCP1 — PORTC bit 2 / Capture/Compare/PWM 1 |
| Pin 14 | RC3 — PORTC bit 3 |
| Pin 15 | RC4 — PORTC bit 4 |
| Pin 16 | RC5 — PORTC bit 5 |
| Pin 17 | RC6/TX/CK — PORTC bit 6 / USART TX |
| Pin 18 | RC7/RX/DT — PORTC bit 7 / USART RX |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage |
| Pin 21 | RB0/INT0 — PORTB bit 0 / External interrupt 0 |
| Pin 22 | RB1/INT1 — PORTB bit 1 / External interrupt 1 |
| Pin 23 | RB2 — PORTB bit 2 |
| Pin 24 | RB3 — PORTB bit 3 |
| Pin 25 | RB4 — PORTB bit 4 |
| Pin 26 | RB5 — PORTB bit 5 |
| Pin 27 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 28 | RB7/PGD — PORTB bit 7 / ICSP data |
Typical Applications
PIC18F2431-I/SP is suitable for 6 applications: Sensorless BLDC Motor Drive, Sensored BLDC with Quadrature Encoder, Digital Power Factor Correction (PFC), Digital Switched-Mode Power Supply, Automotive LIN Body Electronics, Industrial Variable Frequency Drive.
Sensorless BLDC Motor Drive
The PIC18F2431-I/SP is purpose-built for sensorless BLDC motor commutation. Its Power Control PWM module generates three complementary phase outputs with hardware dead-band insertion, eliminating the shoot-through risk in three-phase inverter bridges. The 10-bit 200 ksps ADC samples back-EMF zero-cross events during PWM off-time with sub-microsecond timing accuracy, while the 40 MHz MIPS core executes Microchip AN1078 Back-EMF state-machine firmware with margin. Place the MCU near the gate-driver stage and route PWM outputs through 100 ns-rated traces to minimize switching skew between the MCU and the bridge.
Recommended
Sensored BLDC with Quadrature Encoder
For sensored BLDC and closed-loop position control, the PIC18F2431's Motion Feedback Module decodes quadrature encoder A/B channels and 16-bit timers in hardware, offloading speed calculation from the CPU. This allows a single MCU to manage the commutation state machine, PID velocity loop, and UART telemetry at 40 MHz without CPU saturation. Use the quadrature index pulse once-per-revolution for absolute commutation alignment, and route the encoder signals through differential RC filters placed within 25 mm of the MCU pins.
Recommended
Digital Power Factor Correction (PFC)
The PIC18F2431-I/SP drives digital PFC stages by combining a high-resolution 14-bit PWM channel (used for boost converter duty control) with the high-speed 10-bit ADC to sample inductor current and rectified mains voltage in real time. At 40 MHz the MCU executes average-current-mode control loops with sufficient MIPS headroom for harmonic shaping algorithms that meet EN61000-3-2. Reference firmware is available in Microchip application note AN1208, including the specific MCU configuration bits and ADC trigger synchronization.
Recommended
Digital Switched-Mode Power Supply
The PIC18F2431-I/SP serves as the controller for digitally-controlled SMPS designs up to several hundred watts. Its Power Control PWM generates complementary gate-drive signals with programmable dead-band for synchronous rectifier topologies, while the 10-bit ADC closes output voltage and current loops at 200 ksps. With 16 KB Flash and 768 B RAM the MCU fits full state-machine plus PI loop code for buck, boost, or LLC topologies. For higher-resolution control consider migrating to a dsPIC33FJ12MC202-I/SO which adds DSP instructions.
Recommended
Automotive LIN Body Electronics
The PIC18F2431-I/SP integrates a LIN-capable USART with automatic baud-rate detection, making it suitable for LIN 1.x/2.0 slave nodes that control seats, mirrors, or interior lighting. Operating from 4.2 V to 5.5 V, it accepts power from automotive 12 V rails through a 5 V LDO. The 8 MHz internal oscillator provides a stable LIN bit-clock without external crystals, reducing BOM cost. Use the nanoWatt sleep mode for quiescent current under 100 uA during LIN bus inactivity.
Recommended
Industrial Variable Frequency Drive
The PIC18F2431-I/SP runs industrial VFDs for small three-phase induction motors and pumps. The Power Control PWM provides three complementary pairs with dead-band, the Motion Feedback Module handles tachometer or encoder feedback, and the 10-bit ADC monitors DC bus voltage and phase currents. Operating up to 85C (industrial grade) the MCU sits comfortably in a sealed motor-drive enclosure with adequate copper pour for thermal dissipation. Reference design AN1157 demonstrates scalar V/f control on this exact peripheral set.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F2431-I/SP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F2331-I/SP | PIC18F2431-I/SO | PIC18F2431-E/SP | PIC18F4331-I/SP |
|---|---|---|---|---|---|
| Package | 28-pin SPDIP | 28-pin SPDIP (same) | 28-pin SOIC (different footprint, same die) | 28-pin SPDIP (same) | 28-pin SPDIP (same) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 16 KB Flash | 8 KB Flash | 16 KB Flash (same) | 16 KB Flash (same) | 16 KB Flash (same) |
| RAM | 768 bytes | 256 bytes | 768 bytes (same) | 768 bytes (same) | 768 bytes (same) |
| Max CPU Speed | 40 MHz | 40 MHz (same) | 40 MHz (same) | 40 MHz (same) | 40 MHz (same) |
| PWM Channels | 8 (Power Control PWM) | 8 (Power Control PWM) | 8 (Power Control PWM) | 8 (Power Control PWM) | 8 (Power Control PWM) |
| Quadrature Encoder Interface | Yes (Motion Feedback Module) | Yes (Motion Feedback Module) | Yes (same) | Yes (same) | Yes (same) |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C (same) | -40C to +85C (same) | -40C to +125C (Extended) | -40C to +85C (same) |
| I/O Pins | 25 | 25 | 25 | 25 | 36 (40/44-pin package family) |
Key Differentiators
- Integrated Power Control PWM with hardware dead-band (vs PIC18F2331-I/SP)
- Surface-mount SOIC variant available (vs PIC18F2431-I/SO)
- Extended temperature grade variant (vs PIC18F2431-E/SP)
- Same peripheral set as the larger 40/44-pin PIC18F4331 (vs PIC18F4331-I/SP)
Design Notes
The PIC18F2431-I/SP requires a regulated 4.2 V to 5.5 V supply on each VDD pin. Place a 100 nF decoupling capacitor adjacent to every VDD/VSS pair (pins 8/20, plus AVDD/AVSS if used) and a single bulk 10 uF tantalum or ceramic capacitor at the board entry point. For noise-sensitive analog sampling (current sense), add a ferrite bead in series with AVDD and bypass with 100 nF + 10 uF. Inductive loads driven by the PWM outputs can inject supply transients; size the bulk capacitor so that VDD never drops below 4.2 V during the worst-case MOSFET switching event.
Estimated: At 40 MHz CPU clock with all peripherals active, the PIC18F2431-I/SP core draws approximately 22 mA from a 5 V supply, dissipating roughly 110 mW. In the 28-pin SPDIP package with typical theta_JA near 60 C/W, the junction rises 6.6 C above ambient at room temperature - well within the 125 C absolute maximum. In sealed enclosures with no airflow, derate to 32 MHz or place the MCU near a thermal-via copper pour to keep the junction below 85 C for long-term reliability.
Route the PWM outputs (RC2/CCP1 plus additional PWM-capable pins on PORTB/PORTC) with matched trace lengths to the gate driver inputs. Keep PWM traces short and far from analog signals - a 25 mm guard band around the ADC traces is sufficient. Use a 4-layer PCB with continuous ground plane beneath the MCU to minimize digital switching noise coupling into analog inputs. Place the ICSP connector (RB6/RB7, MCLR) at the board edge to allow in-circuit debug without removing jumpers.
Configuration bits must be set correctly in code or the MCU may execute with the wrong oscillator mode. Always program the FOSC bits for HS or EC mode when using an external crystal or clock. The MCLR pin (pin 1) must never be left floating - tie it to VDD through a 10 kohm resistor and add a 100 nF capacitor to ground for noise immunity. Do not use PORTB internal weak pull-ups on RB0/RB1 when these pins drive the PWM fault inputs, as the pull-up can mask a fault condition.
When using the Motion Feedback Module with a quadrature encoder, route the A and B signals as a differential pair with matched impedance and add 1 kohm series termination at the MCU pins to suppress ringing. Keep encoder traces away from PWM and gate-drive traces to prevent capacitive crosstalk, which can introduce phantom count events at high speeds. For best noise immunity, configure the encoder input filter (QEI filter prescaler) to ignore pulses shorter than one PWM period.
Compliance Information
RoHS compliant per Microchip product page. The industrial I/SP grade is not AEC-Q100 qualified; PIC18F2431-E/SP is the automotive-spec variant. All Microchip PIC18F family parts are lead-free and halogen-free per Microchip Material Declaration.
