PIC18F4431-I/ML - 8-Bit 40MHz 16KB Flash MCU 44-QFN | Microchip
MPN: PIC18F4431-I/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.5 | $7.50 |
| 10 | $6.75 | $67.50 |
| 100 | $6 | $600.00 |
| 500 | $5.4 | $2,700.00 |
| 1,000 | $4.85 | $4,850.00 |
PIC18F4431-I/ML Overview
What is a PIC18F microcontroller? A PIC18F is a high-performance 8-bit CMOS Flash microcontroller family from Microchip Technology, architected around an enhanced RISC instruction set. PIC18F devices occupy a tier above PIC16F parts in Microchip's product hierarchy: 8-bit microcontroller -> Flash MCU -> PIC18 family -> enhanced Flash MCU with nanoWatt technology. The family is widely deployed in consumer, industrial, and automotive subsystems where deterministic real-time control, low sleep current, and on-chip analog peripherals reduce external component count.
Key features of the PIC18F4431 include 16KB Flash with 10,000 erase/write cycles endurance, 768 bytes of RAM, 256 bytes of EEPROM, nanoWatt power management with multiple idle/sleep modes, and a Power Control PWM (PCPWM) module with up to eight complementary outputs and programmable dead-band delay. The 10-bit ADC offers 9 channels with auto-acquisition, and the device includes a USART, MSSP (SPI/I2C), and four 16-bit timers suitable for closed-loop control loops.
The PIC18F4431's 44-QFN package exposes 34 I/O lines and integrates a high-current sink/source capability of 25 mA per pin, which simplifies driving power MOSFET bridges through external gate drivers. The 8-bit Harvard architecture executes most instructions in one cycle (4-clock Tcy) at 40 MHz, giving 10 MIPS throughput. Internal Phase-Locked Loop (PLL) options multiply the external crystal up to the operating frequency, while the nanoWatt features reduce standby current below typical battery-monitoring thresholds.
Typical applications include BLDC and PMSM motor control, three-phase UPS and inverter stages, switch-mode power supply (SMPS) digital control loops, industrial fan and pump drives, HVAC compressor controllers, and low-end servo positioning. The integrated PCPWM block eliminates an external PWM controller, reducing BOM cost and PCB area in motor-drive designs.
When designing with this device, ensure the Vdd/Vss decoupling network uses a 100 nF ceramic capacitor placed within 5 mm of each power pin pair, and a 10 uF bulk tantalum or aluminum-polymer capacitor on each power rail. For high-noise motor environments, add a ferrite bead on the supply line. The MCLR reset pin should be pulled up to Vdd through a 10 kohm resistor, with the optional MCLR capacitor omitted if in-circuit debugging (ICD) is required.
This page synthesizes distributor pricing, drop-in alternatives from the PIC18F family, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC18F4431-I/ML — 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 PIC18F4431-I/ML (same form factor and footprint) — differing in Operating Temperature, Communication, Core Architecture, Package, ADC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F4331-I/ML
✅ Drop-In✓ In Stock
$5.32 / Unit
View Datasheet →PIC18F2431-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2331-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4431-I/ML Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 8-bit RISC |
| Program Memory Type | Enhanced Flash |
| Program Memory Size | 16 KB (8K x 16) |
| RAM Size | 768 bytes |
| EEPROM Size | 256 bytes |
| Maximum CPU Clock | 40 MHz |
| Instruction Throughput | 10 MIPS |
| Supply Voltage (Vdd) | 4.2 V to 5.5 V |
| I/O Pins | 34 |
| ADC | 10-bit, 9 channels |
| PWM Module | Power Control PWM, 8 complementary outputs with programmable dead-band |
| Communication | 1x USART, 1x MSSP (SPI / I2C) |
| Timers | 4 x 16-bit |
| Package | 44-pin QFN (8x8 mm) |
| Operating Temperature | -40 C to +85 C (Industrial, -I suffix) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited) |
| RoHS Status | Compliant |
PIC18F4431-I/ML Pin Configuration
| Pin 1 | MCLR — Master Clear (reset) input, internal pull-up, drive low to reset |
| Pin 2 | OSC1/RA7 — External oscillator input / GPIO RA7 |
| Pin 3 | OSC2/RA6 — External oscillator output / GPIO RA6 |
| Pin 4 | RA0/AN0 — GPIO RA0 / ADC input AN0 |
| Pin 5 | RA1/AN1 — GPIO RA1 / ADC input AN1 |
| Pin 6 | RA2/AN2 — GPIO RA2 / ADC input AN2 |
| Pin 7 | RA3/AN3 — GPIO RA3 / ADC input AN3 |
| Pin 8 | RA4/AN4 — GPIO RA4 / ADC input AN4 |
| Pin 9 | RA5/AN5 — GPIO RA5 / ADC input AN5 |
| Pin 10 | Vss — Ground reference |
| Pin 11 | VDD — Positive supply (4.2 V to 5.5 V) |
| Pin 12 | RB0/INT0 — GPIO RB0 / external interrupt 0 |
| Pin 13 | RB1/INT1 — GPIO RB1 / external interrupt 1 |
| Pin 14 | RB2/INT2 — GPIO RB2 / external interrupt 2 |
| Pin 15 | RB3/CCP2 — GPIO RB3 / Capture-Compare-PWM 2 |
| Pin 16 | RB4 — GPIO RB4 |
| Pin 17 | RB5 — GPIO RB5 |
| Pin 18 | RB6/PGC — GPIO RB6 / ICSP clock |
| Pin 19 | RB7/PGD — GPIO RB7 / ICSP data |
| Pin 20 | Vss — Ground reference |
| Pin 21 | VDD — Positive supply (4.2 V to 5.5 V) |
| Pin 22 | RC0/T1OSO — GPIO RC0 / Timer1 oscillator output |
| Pin 23 | RC1/T1OSI — GPIO RC1 / Timer1 oscillator input |
| Pin 24 | RC2/CCP1 — GPIO RC2 / Capture-Compare-PWM 1 |
| Pin 25 | RC3/SCK/SCL — GPIO RC3 / MSSP clock (SPI SCK / I2C SCL) |
| Pin 26 | RC4/SDI/SDA — GPIO RC4 / MSSP data (SPI SDI / I2C SDA) |
| Pin 27 | RC5/SDO — GPIO RC5 / MSSP data out (SPI SDO) |
| Pin 28 | RC6/TX/CK — GPIO RC6 / USART asynchronous TX or synchronous clock |
| Pin 29 | RC7/RX/DT — GPIO RC7 / USART asynchronous RX or synchronous data |
| Pin 30 | Vss — Ground reference |
| Pin 31 | VDD — Positive supply (4.2 V to 5.5 V) |
| Pin 32 | RD0/PWM0 — GPIO RD0 / Power Control PWM output 0 |
| Pin 33 | RD1/PWM1 — GPIO RD1 / Power Control PWM output 1 |
| Pin 34 | RD2/PWM2 — GPIO RD2 / Power Control PWM output 2 |
| Pin 35 | RD3/PWM3 — GPIO RD3 / Power Control PWM output 3 |
| Pin 36 | RD4/PWM4 — GPIO RD4 / Power Control PWM output 4 |
| Pin 37 | RD5/PWM5 — GPIO RD5 / Power Control PWM output 5 |
| Pin 38 | RD6/PWM6 — GPIO RD6 / Power Control PWM output 6 |
| Pin 39 | RD7/PWM7 — GPIO RD7 / Power Control PWM output 7 |
| Pin 40 | Vss — Ground reference |
| Pin 41 | VDD — Positive supply (4.2 V to 5.5 V) |
| Pin 42 | RE0/PWM8 — GPIO RE0 / Power Control PWM output 8 |
| Pin 43 | RE1/PWM9 — GPIO RE1 / Power Control PWM output 9 |
| Pin 44 | RE2/PWM10 — GPIO RE2 / Power Control PWM output 10 |
Typical Applications
PIC18F4431-I/ML is suitable for 6 applications: BLDC Motor Control, Switch-Mode Power Supply (SMPS) Digital Control, Industrial Fan and Pump Drives, HVAC Compressor Controllers, Uninterruptible Power Supply (UPS) Inverter Stage, Low-End Servo and Positioning Controllers.
BLDC Motor Control
The PIC18F4431-I/ML is purpose-built for BLDC and PMSM motor control because its Power Control PWM module provides up to eight complementary outputs with programmable dead-band delay that prevents shoot-through in a three-phase inverter bridge. With 10 MIPS throughput from the 40 MHz oscillator, the CPU can run a sensorless back-EMF zero-crossing algorithm and a closed-loop PI speed controller at typical PWM frequencies of 20 to 50 kHz while leaving headroom for housekeeping tasks. The 10-bit ADC with 9 channels samples phase currents and DC-bus voltage simultaneously, and the high-current 25 mA I/O pins simplify interfacing to gate-driver ICs such as the IR2104 or MCP14E1. Compared with a discrete analog control loop, the integrated solution reduces BOM count and PCB area.
Recommended
Switch-Mode Power Supply (SMPS) Digital Control
The PIC18F4431-I/ML's high-resolution 14-bit PCPWM and fast 10 MIPS CPU make it suitable as a digital controller for isolated and non-isolated SMPS topologies such as half-bridge, full-bridge, and active-clamp forward converters. The ADC samples the output voltage and primary current at the start of each PWM cycle, and the firmware implements peak-current-mode or average-current-mode control with slope compensation. With 16 KB of Flash, complex state machines, soft-start sequencing, and supervisory housekeeping fit comfortably; 768 bytes of RAM is adequate for control variables, and 256 bytes of EEPROM store calibration constants. Compared with analog UC3842-style controllers, the digital loop enables adaptive compensation and telemetry.
Recommended
Industrial Fan and Pump Drives
Variable-frequency drives for industrial fans and centrifugal pumps benefit from the PIC18F4431-I/ML because it integrates the three-phase PWM, ADC feedback, and supervisory logic in one IC. The PCPWM generates the six PWM signals required for a three-phase IGBT inverter at carrier frequencies up to about 25 kHz, while the ADC measures the DC bus voltage and phase currents for sensorless V/Hz or space-vector-modulation control. The 34 I/O pins cover enable inputs, fault outputs, tachometer feedback, and a USART that links to a Modbus RTU master. Compared with a discrete DSP plus logic-IC implementation, this MCU reduces system cost while keeping firmware updateable in the field.
Recommended
HVAC Compressor Controllers
In HVAC compressor and blower drives, the PIC18F4431-I/ML provides deterministic motor control plus room for safety and communications firmware. The 16 KB Flash holds sensorless sinusoidal commutation tables, current-limit ramps, and a UART-based service interface, while the 768 B RAM covers state variables and the 256 B EEPROM stores compressor-matching parameters across power cycles. The industrial -40 C to +85 C temperature range handles under-hood or rooftop-unit environments. Compared with a fixed-function motor controller, the PIC18F4431-I/ML adds soft-start profiles, brown-out handling, and field-reprogrammable tuning without hardware changes.
Recommended
Uninterruptible Power Supply (UPS) Inverter Stage
Low-to-medium power UPS inverter stages use the PIC18F4431-I/ML to generate the AC sine output through the PCPWM module driving an H-bridge or three-phase IGBT bridge. The ADC senses battery voltage, output current, and temperature, while the firmware implements a digital sine-PWM generator and a closed-loop RMS voltage regulator. With 16 KB Flash the device can hold multiple output-voltage profiles (120 V / 230 V, 50 Hz / 60 Hz) selectable through I/O, and 256 B EEPROM stores the calibration constants per profile. Compared with pure analog oscillator designs, the digital approach delivers better THD and faster load-step response.
Recommended
Low-End Servo and Positioning Controllers
For small stepper or DC servo positioning controllers in industrial automation, the PIC18F4431-I/ML combines sufficient CPU bandwidth, PWM, ADC, and USART in a single 44-QFN device. The PCPWM drives a single H-bridge at up to 50 kHz with directional logic, the ADC reads a potentiometer or encoder feedback, and the USART links to a PLC or HMI. With 34 I/O pins the controller handles limit switches, brake control, and indicator LEDs without a logic expander. Compared with a discrete analog servo amplifier, this MCU offers programmable acceleration/deceleration ramps and absolute positioning from EEPROM-stored setpoints.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F4431-I/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4331-I/ML | PIC18F2431-I/ML | PIC18F2331-I/ML |
|---|---|---|---|---|
| Package | 44-QFN (8x8 mm) | 44-QFN (8x8 mm) - same | 28-QFN (6x6 mm) - smaller, drop-in only for I/O subset | 28-QFN (6x6 mm) - smaller, drop-in only for I/O subset |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 16 KB Flash | 8 KB Flash (-50%) | 16 KB Flash (same) | 8 KB Flash (-50%) |
| RAM | 768 bytes | 768 bytes (same) | 768 bytes (same) | 768 bytes (same) |
| Maximum CPU Clock | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS (same) | 40 MHz / 10 MIPS (same) | 40 MHz / 10 MIPS (same) |
| Supply Voltage | 4.2 V to 5.5 V | 4.2 V to 5.5 V (same) | 4.2 V to 5.5 V (same) | 4.2 V to 5.5 V (same) |
| I/O Pins | 34 | 34 (same) | 24 (-29%) | 24 (-29%) |
| PWM Module | PCPWM, 8 complementary outputs | PCPWM, 8 complementary outputs (same) | PCPWM, 6 complementary outputs | PCPWM, 6 complementary outputs |
| ADC | 10-bit, 9 channels | 10-bit, 9 channels (same) | 10-bit, 5 channels | 10-bit, 5 channels |
Key Differentiators
- Half-memory variant on identical 44-QFN footprint (vs PIC18F4331-I/ML)
- Integrated Power Control PWM for three-phase inverters (vs PIC18F458-I/ML)
- More I/O and more PWM channels than 28-pin family members (vs PIC18F2431-I/ML)
Design Notes
Place a 100 nF ceramic decoupling capacitor within 5 mm of every Vdd/Vss pin pair on the PIC18F4431-I/ML, and add a single 10 uF bulk tantalum or aluminum-polymer capacitor on each power rail. AVDD must be tied directly to VDD with its own local 100 nF bypass to avoid ADC reference noise. For motor-drive boards with high dI/dt events, a ferrite bead on the supply line reduces conducted noise from the power stage entering the MCU supply. These practices typically keep Vdd ripple below 50 mV peak-to-peak.
The 44-QFN exposed thermal pad (EP) on the PIC18F4431-I/ML must be soldered to a continuous ground plane for both electrical performance and thermal dissipation; missing or partial EP soldering can cause device malfunction and overtemperature shutdown. Use a via-array pattern of 9 to 16 thermal vias (0.3 mm drill, 0.6 mm pitch) under the EP to spread heat into inner copper layers. The QFN has 0.65 mm pitch, so PCB fabrication should target 4 mil trace/space with solder mask-defined pads to avoid tombstoning on small passive components.
When using the PCPWM module, always program a non-zero dead-band delay before enabling the complementary outputs, otherwise shoot-through can damage the external MOSFET bridge. The PIC18F4431's BOR (brown-out reset) is factory-trimmed to a specific threshold and should not be disabled in motor applications because a low-Vdd event can corrupt Flash and EEPROM. Estimate: at Vdd=5 V and 25 mA source current, sourcing 34 I/O simultaneously would draw 850 mA, which exceeds the absolute maximum I/O source specification, so outputs must be toggled in groups to limit total pin current.
Keep the high-current PWM traces (RD0-RD7, RE0-RE2) short and wide to minimize switching transients, and route the analog ADC inputs (AN0-AN8) away from the PWM traces to avoid capacitive coupling. The MCLR pin should be pulled up to VDD through a 10 kohm resistor; if in-circuit debugger (ICD) is required, omit the optional MCLR capacitor and route the ICSP clock/data lines (RB6/PGC, RB7/PGD) directly to the debug header. Place a 4.7 kohm to 10 kohm pull-up on RB6 and RB7 only if no ICD is connected in production.
Compliance Information
RoHS and REACH compliant per Microchip product page; matte-tin lead finish on /ML package. Not AEC-Q100 qualified - for automotive, choose a Q-grade part number. Halogen-free per Microchip environmental certification.