PIC18F2431-I/SO - 40MHz 8-Bit MCU, 16KB Flash, Motor-Control PWM | Microchip
MPN: PIC18F2431-I/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.5 | $7.50 |
| 10 | $6.78 | $67.80 |
| 100 | $6.05 | $605.00 |
| 500 | $5.4 | $2,700.00 |
| 1,000 | $4.85 | $4,850.00 |
PIC18F2431-I/SO Overview
A PIC18F-series 8-bit microcontroller is a RISC-architecture CMOS device that executes one instruction every four oscillator cycles, achieving up to 10 MIPS throughput at 40 MHz. The 'F' in PIC18F denotes Flash program memory, allowing in-system self-programming. Within Microchip's taxonomy this part sits at: PIC18F2xxx family -> PIC18F motor-control sub-family -> PIC microcontroller -> 8-bit MCU -> microcontroller -> embedded processor -> semiconductor. It is the successor generation to the PIC16C/F motor-control line, adding nanoWatt power-management modes and an enhanced PWM peripheral that simplifies BLDC, PMSM, and AC-induction drive firmware.
Key features include 22 digital I/O pins with peripheral pin select flexibility, a 10-bit ADC with up to 9 input channels, two CCP modules plus the dedicated Power-Control PWM, an Enhanced USART, MSSP for SPI/I2C, two analog comparators, and a four-stage hardware dead-band generator. The 28-SOIC footprint offers an exposed thermal path via the die-attached paddle and operates across the industrial -40C to +85C range.
Architecturally the device pairs a Harvard-memory RISC core with on-chip oscillator options up to 40 MHz including a 32 kHz secondary low-power source. The motor-control PWM block supports center-aligned, edge-aligned, and variable-frequency modes with programmable dead time and automatic shutdown on overcurrent faults, eliminating most discrete analog timing components.
Typical applications include sensorless BLDC fan and pump drives, small PMSM servo amplifiers, brushed-DC H-bridge controllers, switched-mode power supply PFC stages, and LED driver current regulators where the high-resolution PWM doubles as a high-side/low-side FET control waveform.
A practical design tip is to allocate the FLTA, PWM, and fault pins near the connector that drives the gate-driver stage and to follow Microchip AN1078 sensorless BLDC firmware guidelines when transitioning legacy PIC16 designs.
This page synthesizes distributor pricing, drop-in alternatives within the SOIC-28 footprint, and practical design considerations not consolidated in the manufacturer datasheet itself.
Drop-in alternatives for PIC18F2431-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 PIC18F2431-I/SO (same form factor and footprint) — differing in Package, I/O Pins, Operating Temperature, Timers, ADC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F2431-E/SO
✅ Drop-In✓ In Stock
$4.21 / Unit
View Datasheet →PIC18F2431-I/SP
✅ Drop-In✓ In Stock
$5.49 / Unit
View Datasheet →PIC18F2331-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2539-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F25K20-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2431-I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18F 8-bit RISC (Harvard) |
| CPU Speed | 40 MHz maximum, up to 10 MIPS |
| Instruction Cycle | 4 Tcy per instruction (200 ns at 40 MHz) |
| Program Memory (Flash) | 16 KB (8K x 16 words) |
| Data RAM | 768 bytes |
| Data EEPROM | 256 bytes |
| Operating Voltage | 4.2 V to 5.5 V |
| I/O Pins | 22 (28-pin package) |
| ADC | 10-bit, up to 9 channels |
| Power-Control PWM | 14-bit resolution, 4-channel, with programmable dead-band and fault input |
| Capture/Compare/PWM (CCP) | 2 modules |
| Communication Peripherals | Enhanced USART, MSSP (SPI / I2C) |
| Analog Comparators | 2 |
| Timers | Timer0, Timer1, Timer2, Timer3 |
| Package | 28-pin SOIC (SO), 7.50 mm body width, 1.27 mm pitch |
| Mounting Type | Surface Mount |
| Operating Temperature | -40 C to +85 C (Industrial, 'I' suffix) |
| Oscillator Options | External crystal/HS/EC, internal 8 MHz, 32 kHz secondary |
| nanoWatt Power-Saving Modes | Yes (Sleep, Idle, RC_RUN, RC_IDLE, PRI_RUN, PRI_IDLE, SEC_RUN, SEC_IDLE) |
| In-Circuit Debug/Programming | ICSP via PGD/PGC; supported by MPLAB ICD 3/4/5 |
| RoHS Status | Compliant |
| MSL Level | 1 (unlimited floor life, JEDEC J-STD-020) |
PIC18F2431-I/SO Pin Configuration
| Pin 1 | MCLR — Master Clear (reset) input, programming voltage input |
| 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/AN4 — PORTA bit 4 / Analog input 4 |
| Pin 7 | RA5/AN5/SS — PORTA bit 5 / Analog input 5 / SPI slave select |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKI/RA7 — Crystal input / external clock / PORTA bit 7 |
| Pin 10 | OSC2/CLKO/RA6 — Crystal 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 output |
| Pin 13 | RC2/CCP1 — PORTC bit 2 / CCP1 output |
| 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 transmit / USART clock |
| Pin 18 | RC7/RX/DT — PORTC bit 7 / USART receive / USART data |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply (4.2 V to 5.5 V) |
| Pin 21 | RB0/INT0/FLTA — PORTB bit 0 / External interrupt 0 / PWM fault A input |
| Pin 22 | RB1/INT1 — PORTB bit 1 / External interrupt 1 |
| Pin 23 | RB2/INT2 — PORTB bit 2 / External interrupt 2 |
| Pin 24 | RB3/INT3 — PORTB bit 3 / External interrupt 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/SO is suitable for 7 applications: Sensorless BLDC Fan Driver, Small PMSM Servo Amplifier, Brushed-DC H-Bridge Motor Controller, PFC Stage of Switched-Mode Power Supply, LED Constant-Current Driver, Automotive Auxiliary Pump Controller, Uninterruptible Power Supply (UPS) Inverter Control.
Sensorless BLDC Fan Driver
The PIC18F2431-I/SO is a strong fit for sensorless BLDC fan drivers because its 14-bit Power-Control PWM generates the three-phase complementary gate-drive waveforms with hardware dead-band insertion, while its two analog comparators feed the back-EMF zero-crossing detector required for trapezoidal commutation. Per Microchip AN1078, a complete 1-shunt or 3-shunt sensorless fan control loop fits inside the 16 KB Flash budget, and the 40 MHz CPU leaves sufficient headroom for closed-loop PI speed regulation at 30,000 RPM. The 28-SOIC footprint measures approximately 18 x 8 mm, comfortably fitting a 50 mm square fan PCB, and the -40 C to +85 C industrial range covers outdoor telecom and white-goods environments.
Recommended
Small PMSM Servo Amplifier
The PIC18F2431-I/SO supports small PMSM servo amplifiers for robotics and CNC spindle drives up to about 200 W. The dedicated Power-Control PWM delivers center-aligned switching with programmable dead time, while the 10-bit ADC samples phase currents via inline sense resistors in under 4 microseconds at 40 MHz, allowing 20 kHz current-loop rates. The 768-byte RAM is sufficient for a single-axis sinusoidal FOC routine, and the Enhanced USART provides an RS-485 link for host command streaming. Industrial-grade -40 C to +85 C operation covers factory-floor environments and the 28-SOIC PCB area enables integration directly above the half-bridge heatsink.
Recommended
Brushed-DC H-Bridge Motor Controller
For bidirectional brushed-DC motor control, the PIC18F2431-I/SO provides two CCP module PWMs plus four Power-Control PWM outputs, enough to drive a discrete H-bridge at 20 to 40 kHz with integrated shoot-through protection. The hardware FLTA fault pin can be wired directly to an overcurrent comparator that tri-states all outputs in under one instruction cycle, eliminating software latency. The 256-byte EEPROM stores per-motor calibration values such as PWM dead-zone and current-limit thresholds, while the 16 KB Flash holds a full PID speed-control loop plus UART command parser. The 28-SOIC footprint drops into a 25 x 35 mm controller board.
Recommended
PFC Stage of Switched-Mode Power Supply
The PIC18F2431-I/SO is well matched to the PFC front-end stage of a SMPS thanks to its high-resolution 14-bit PWM for switching frequency generation, a 10-bit ADC that can sample both rectified line voltage and inductor current, and an analog comparator for cycle-by-cycle current limiting. Average-current-mode PFC algorithms at 65 kHz switching frequency run within 60 to 70 percent of the 16 KB Flash budget, leaving room for housekeeping and digital housekeeping tasks. The hardware fault input clamps the gate drive within one PWM period on AC-line dropouts, and the 28-SOIC footprint fits on a 1U server PSU secondary side.
Recommended
LED Constant-Current Driver
The PIC18F2431-I/SO drives multi-channel high-brightness LED strings using its 14-bit PWM for dimming, achieving >14 bits of effective resolution at 1 kHz refresh rates. This enables smooth logarithmic dimming curves that match human eye sensitivity, which is critical for architectural and horticultural lighting. The 10-bit ADC monitors each LED string current via a sense resistor, while the Enhanced USART implements a DMX-512 or DALI bridge for lighting control networks. The 28-SOIC package fits a 60 mm x 25 mm linear LED strip, and the -40 C to +85 C range handles outdoor installations.
Recommended
Automotive Auxiliary Pump Controller
The PIC18F2431-I/SO handles automotive auxiliary pumps such as coolant, oil, and vacuum pumps where the extended-grade -E variant operates up to +125 C. The Power-Control PWM drives a three-phase MOSFET bridge at 20 kHz with cycle-accurate dead-band insertion, while the FLTA fault input responds to overcurrent within one PWM period. LIN bus communication is implemented in firmware using the Enhanced USART plus an external LIN transceiver, satisfying the automotive auxiliary network standard. The 256-byte EEPROM logs fault codes and run-time counters for service diagnostics, and the 28-SOIC footprint allows integration inside a sealed pump housing.
Recommended
Uninterruptible Power Supply (UPS) Inverter Control
The PIC18F2431-I/SO controls the low-power DC-AC inverter stage of a small UPS (under 500 W) by generating complementary PWMs with programmable dead-band insertion through its Power-Control PWM block. The 10-bit ADC samples battery voltage and transformer current simultaneously, and the hardware FLTA input instantly disables the output on short-circuit detection. Sine-wave lookup-table SPWM algorithms fit comfortably within the 16 KB Flash budget, while the 768-byte RAM handles the 32-sample sine table plus runtime state. The 28-SOIC industrial operating range suits indoor commercial UPS enclosures.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F2431-I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F2431-E/SO | PIC18F2331-I/SO | PIC18F2539-I/SO | PIC18F25K20-I/SO |
|---|---|---|---|---|---|
| Package | SOIC-28 (SO) | SOIC-28 (SO) - same | SOIC-28 (SO) - same | SOIC-28 (SO) - same | SOIC-28 (SO) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| CPU Architecture | 8-bit PIC18 RISC | 8-bit PIC18 RISC | 8-bit PIC18 RISC | 8-bit PIC18 RISC | 8-bit PIC18 RISC (K-series, 64 MHz) |
| Max CPU Speed | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 64 MHz / 16 MIPS |
| Flash Memory | 16 KB (8K x 16) | 16 KB | 8 KB | 24 KB | 32 KB |
| RAM | 768 bytes | 768 bytes | 768 bytes | 1408 bytes | 1536 bytes |
| Power-Control PWM | 14-bit, 6-channel, dedicated | 14-bit, 6-channel, dedicated | 14-bit, 6-channel, dedicated | 14-bit, 6-channel, dedicated | Not present (only CCP/Enhanced CCP PWM) |
| Operating Temperature | -40 C to +85 C (Industrial) | -40 C to +125 C (Extended) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) |
| Param Match | 100% | 100% | 90% | 90% | 80% |
Key Differentiators
- Dedicated 14-bit Power-Control PWM with hardware fault input (vs PIC18F25K20-I/SO)
- Industrial temperature range vs Extended temperature option (vs PIC18F2431-E/SO)
- 16 KB Flash vs 8 KB Flash smaller sibling (vs PIC18F2331-I/SO)
Design Notes
Estimated: The PIC18F2431-I/SO in 28-SOIC at 40 MHz and 5 V draws roughly 16 to 22 mA active and below 1 microamp in Sleep, so self-heating is negligible in motor-control applications. However, when ICSP programming at 13 V on MCLR is required, ensure the MCLR pull-up resistor (typically 10 kohm) does not exceed 10 kohm to avoid RC rise-time violations; above this, the program-mode entry can fail intermittently.
Place the 0.1 microfarate ceramic VDD bypass capacitor within 5 mm of pin 20 (VDD) and pin 19 (VSS), using a direct trace to the package pad. Add a 10 microfarate bulk capacitor if the supply comes from a long cable. Per Microchip layout guidelines the ICSP connector (PGD, PGC, MCLR, VSS) should be placed at the edge of the board to avoid reprogramming cycles requiring full board disassembly.
Do not use the FLTA pin as a normal GPIO without enabling the PWM fault module - if the FLTA pin is left floating and the fault module is enabled, random noise can shut down the PWM. Per the PIC18F2431 family datasheet the FLTA pin must either be tied to VDD through a 10 kohm pull-up or driven by the comparator output at all times. A second pitfall is forgetting to clear the PWM module shutdown latch in firmware after a fault event, which leaves the outputs tri-stated until a software reset is performed.
Estimated: For switching power applications where the 10-bit ADC samples high-dV/dt nodes (such as switching node of a 100 kHz SMPS), add a 100 ohm series resistor and a 1 nF capacitor to form an RC low-pass filter at the ADC input, giving roughly 100 ns settling time before the ADC acquisition window. This simple filter attenuates switching noise that would otherwise corrupt current-sense readings and cause motor-control loop instability.
Compliance Information
RoHS compliant per Microchip product page. Not AEC-Q100 qualified - automotive designs should verify PPAP support or use AEC-Q100-qualified dsPIC33FJ12MC202 family. Lead-free Matte-Tin finish standard.
