PIC18F4331-I/ML - 8-bit MCU, 40MHz, 8KB Flash, 44-QFN | Microchip
MPN: PIC18F4331-I/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.31 | $8.31 |
| 10 | $7.48 | $74.80 |
| 100 | $6.65 | $665.00 |
| 500 | $5.91 | $2,955.00 |
| 1,000 | $5.32 | $5,320.00 |
PIC18F4331-I/ML Overview
An 8-bit microcontroller (MCU) is a programmable processor core with an 8-bit data path, optimized for deterministic real-time control. Within the broader hierarchy, PIC18F4331 belongs to microcontrollers -> microprocessors -> semiconductor devices -> integrated circuits. Its architectural siblings include the 28-pin PIC18F2331 and 40-pin PIC18F4431, which share the same peripherals but differ in pin count and package. The PIC18 family uses an enhanced Harvard architecture with separate code and data buses, supporting 16-bit instructions and 8-bit data operations for efficient C and assembly code generation.
Key features include a 14-channel 10-bit ADC with up to 100 ksps conversion rate, three on-chip hardware PWM modules (10-bit/14-bit resolution, 4 channels), dual analog comparators with rail-to-rail inputs, nanoWatt power management, and a 16-bit Capture/Compare/PWM (CCP) module. The integrated 40 MHz internal oscillator with PLL reduces external component count, while 34 digital I/O pins support 5V-tolerant operation. Communication peripherals include I2C, SPI, and USART with 9-bit address detection.
The PIC18F4331 is engineered for closed-loop applications where the ADC and PWM must run concurrently with low jitter. The three independent PWM channels can generate complementary outputs with programmable dead-band delay, eliminating shoot-through in half-bridge motor drivers. The 10-bit ADC's 100 ksps throughput enables 10 kHz current sampling in field-oriented control (FOC) loops, while the 768-byte RAM holds two full three-phase SVM lookup tables plus the PI controller state.
Typical applications include brushless DC (BLDC) motor controllers, switched-mode power supplies (SMPS) digital control loops, HVAC fan and pump controllers, LED lighting drivers with constant-current regulation, and small industrial sensor interfaces. The 4.2V to 5.5V supply range aligns directly with rectified mains-derived 5V rails common in appliance-class designs.
When designing with the PIC18F4331-I/ML, route the exposed pad (EP) to a continuous ground pour with at least 8 thermal vias to dissipate ~1W peak dissipation in high-PWM workloads. Keep the 40 MHz crystal traces under 5 mm and isolate them from the PWM output traces to avoid coupling into the gate-driver signals.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical PCB layout notes that are not consolidated on any single distributor listing for the PIC18F4331-I/ML.
Drop-in alternatives for PIC18F4331-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 PIC18F4331-I/ML (same form factor and footprint) — differing in Package, Operating Temperature, Core Architecture, Timers, ADC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F4331-I/PT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$3.05 / Unit
View Datasheet →PIC18F4321-I/ML
✅ Drop-In✓ In Stock
$1.22 / Unit
View Datasheet →PIC18F4431-I/ML
✅ Drop-In✓ In Stock
$4.85 / Unit
View Datasheet →PIC18F4331T-I/ML
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$5.78 / Unit
View Datasheet →PIC18F4331-E/ML
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18F4331-I/ML Maximum Ratings & Electrical Characteristics
| Product Family | PIC18F Microcontroller |
| Core | 8-bit PIC18 enhanced Harvard |
| Program Memory (Flash) | 8 KB (4K x 16 instructions) |
| RAM | 768 bytes |
| EEPROM | 256 bytes |
| Maximum Clock Frequency | 40 MHz |
| Instruction Throughput | 40 MIPS (10 MIPS per MHz, 4-cycle) |
| Supply Voltage (VDD) | 4.2 V to 5.5 V |
| I/O Pins | 34 digital I/O |
| ADC | 10-bit, up to 9 channels, 100 ksps |
| PWM Channels | 3 modules (up to 6 outputs) with dead-band control |
| Comparators | 2 analog comparators |
| Communication | 1x I2C, 1x SPI, 1x EUSART (with LIN) |
| Operating Temperature | -40C to +85C (industrial, "I") |
| Package | 44-pin QFN (8x8 mm) with exposed pad |
| Mounting Type | Surface Mount |
| MSL Level | 3 |
| RoHS Status | Compliant |
PIC18F4331-I/ML Pin Configuration
| Pin 1 | MCLR — Master Clear (Reset) 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 — PORTA bit 2 / Analog input 2 |
| Pin 5 | RA3/AN3 — PORTA bit 3 / Analog input 3 |
| Pin 6 | RA4/AN4 — PORTA bit 4 / Analog input 4 |
| Pin 7 | VSS — Ground reference |
| Pin 8 | VDD — Positive supply (4.2V-5.5V) |
| Pin 9 | RA5/AN5 — PORTA bit 5 / Analog input 5 |
| Pin 10 | RA6/OSC2 — PORTA bit 6 / Oscillator output |
| Pin 11 | RA7/OSC1 — PORTA bit 7 / Oscillator input |
| Pin 12 | RC0 — PORTC bit 0 |
| Pin 13 | RC1 — PORTC bit 1 |
| Pin 14 | RC2 — PORTC bit 2 |
| Pin 15 | RC3 — PORTC bit 3 |
| Pin 16 | RC4 — PORTC bit 4 |
| Pin 17 | RC5 — PORTC bit 5 |
| Pin 18 | RC6 — PORTC bit 6 |
| Pin 19 | RC7 — PORTC bit 7 |
| Pin 20 | VSS — Ground reference |
| Pin 21 | VDD — Positive supply (4.2V-5.5V) |
| Pin 22 | RB0 — PORTB bit 0 / Interrupt-on-change |
| Pin 23 | RB1 — PORTB bit 1 / Interrupt-on-change |
| Pin 24 | RB2 — PORTB bit 2 / Interrupt-on-change |
| Pin 25 | RB3 — PORTB bit 3 / Interrupt-on-change |
| Pin 26 | RB4 — PORTB bit 4 / Interrupt-on-change |
| Pin 27 | RB5 — PORTB bit 5 / Interrupt-on-change |
| Pin 28 | RB6 — PORTB bit 6 / Interrupt-on-change / PGC |
| Pin 29 | RB7 — PORTB bit 7 / Interrupt-on-change / PGD |
| Pin 30 | RD0 — PORTD bit 0 |
| Pin 31 | RD1 — PORTD bit 1 |
| Pin 32 | RD2 — PORTD bit 2 |
| Pin 33 | PWM1L — PWM1 Low-side output |
| Pin 34 | PWM1H — PWM1 High-side output |
| Pin 35 | PWM2L — PWM2 Low-side output |
| Pin 36 | PWM2H — PWM2 High-side output |
| Pin 37 | PWM3L — PWM3 Low-side output |
| Pin 38 | PWM3H — PWM3 High-side output |
| Pin 39 | RE0 — PORTE bit 0 |
| Pin 40 | RE1 — PORTE bit 1 |
| Pin 41 | RE2 — PORTE bit 2 |
| Pin 42 | RE3 — PORTE bit 3 |
| Pin 43 | AVSS — Analog ground |
| Pin 44 | AVDD — Analog supply (4.2V-5.5V) |
| Pin 45 | EP — Exposed Pad - tie to ground for thermal dissipation |
Typical Applications
PIC18F4331-I/ML is suitable for 6 applications: Brushless DC (BLDC) Motor Control, Switched-Mode Power Supply (SMPS) Digital Control, HVAC Fan and Pump Speed Controllers, LED Lighting Constant-Current Drivers, Industrial Sensor Interface and Signal Conditioning, Small Appliance Control Boards.
Brushless DC (BLDC) Motor Control
The PIC18F4331-I/ML is purpose-built for single-shunt sensorless BLDC motor control in appliances, HVAC fans, and small pumps. Its three independent 14-bit PWM modules with complementary outputs and programmable dead-band (0-63 cycles) directly drive three-phase half-bridge gate drivers such as the IR2104, eliminating the need for an external timer. The integrated 10-bit ADC at 100 ksps samples back-EMF or DC-bus shunt current at 10 kHz FOC rates, while 768 bytes of RAM holds two PWM duty-cycle registers, current lookup tables, and the PI state. The 40 MIPS throughput executes a full FOC loop including Clarke/Park transforms in well under 50 microseconds per PWM cycle.
Recommended
Switched-Mode Power Supply (SMPS) Digital Control
The PIC18F4331-I/ML provides a closed-loop digital controller for PFC and DC-DC converters, replacing analog UC3842-class controllers. Its high-speed ADC and PWM modules enable peak-current-mode control of boost PFC stages at 65 kHz switching frequency, while the 5V rail-tolerant I/O directly interfaces to optocoupler feedback paths. The 8 KB Flash accommodates a digital compensator with soft-start, brown-out handling, and adaptive dead-time control. Compared to fixed-function analog controllers, this approach allows firmware upgrade of compensation parameters and adds telemetry reporting through I2C or SPI without external glue logic.
Recommended
HVAC Fan and Pump Speed Controllers
Variable-speed control of 12V/24V brushless fans and circulator pumps uses the PIC18F4331-I/ML as the closed-loop supervisor that drives an external three-phase inverter. The 40 MIPS performance handles back-EMF zero-cross detection in under 10 microseconds per commutation event, allowing sensorless operation above 1,000 RPM with smooth torque delivery. The 4.2V-5.5V supply range aligns with the 5V rail derived from rectified mains, while the 34 I/O lines accommodate keypad input, RPM feedback, fault LEDs, and an isolated I2C link to the system controller.
Recommended
LED Lighting Constant-Current Drivers
Architectural and commercial LED fixtures use the PIC18F4331-I/ML to maintain constant current across multiple strings while providing dimming via 0-10V analog or DALI digital control. The high-frequency PWM (up to 40 MHz time-base) drives a buck or boost converter at >100 kHz with low output current ripple below 1 percent, achieving high-flicker-free performance required by IEEE 1789. The 5V rail and 768-byte RAM support a small PID loop for thermal foldback via NTC input, while the 8 KB Flash stores per-channel calibration constants and dimming curves.
Recommended
Industrial Sensor Interface and Signal Conditioning
Industrial sensor hubs aggregate analog and digital signals from thermocouples, RTDs, strain gauges, and digital switches using the PIC18F4331-I/ML as a mixed-signal front-end controller. The 10-bit ADC with up to 9 channels samples multiple sensors at 100 ksps aggregate, while the on-chip comparators provide threshold detection for alarm outputs without consuming ADC bandwidth. The 256-byte EEPROM stores per-channel calibration coefficients and last-known-good setpoints, surviving power cycles for predictive-maintenance systems. An SPI or I2C interface streams processed data to a higher-level PLC or SCADA node.
Recommended
Small Appliance Control Boards
Small kitchen and white-goods appliances - blenders, induction cooktops, washing-machine drain pumps - integrate the PIC18F4331-I/ML for combined user-interface and motor-control duties. The MCU drives a BLDC or universal motor through its PWM channels, reads capacitive-touch sensors via the analog comparators, scans a 7-segment display through the I/O ports, and implements safety interlocks in software. The 5V-tolerant I/O directly connects to mains-isolated switch networks, while the extended temperature grade ("-I" suffix, -40C to +85C) tolerates the inside-of-cabinet thermal environment.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F4331-I/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4321-I/ML | PIC18F4431-I/ML | PIC18F4331T-I/ML | PIC18F4331-E/ML |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-QFN (8x8 mm) | 44-QFN (8x8 mm) - same | 44-QFN (8x8 mm) - same | 44-QFN (8x8 mm) - same | 44-QFN (8x8 mm) - same |
| Program Flash | 8 KB | 8 KB | 16 KB | 8 KB | 8 KB |
| RAM | 768 bytes | 768 bytes | 768 bytes | 768 bytes | 768 bytes |
| Maximum Clock | 40 MHz / 40 MIPS | 40 MHz / 40 MIPS | 40 MHz / 40 MIPS | 40 MHz / 40 MIPS | 40 MHz / 40 MIPS |
| Dedicated Motor-Control PWM | Yes (3 modules, 14-bit) | No (general CCP only) | Yes (3 modules, 14-bit) | Yes (3 modules, 14-bit) | Yes (3 modules, 14-bit) |
| Temperature Grade | -40C to +85C (Industrial) | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +125C (Extended) |
| ADC Channels / Resolution | 9 channels, 10-bit | 13 channels, 10-bit | 9 channels, 10-bit | 9 channels, 10-bit | 9 channels, 10-bit |
Key Differentiators
- Dedicated 14-bit motor-control PWM with programmable dead-band (vs PIC18F4321-I/ML)
- Doubled program memory headroom with identical footprint (vs PIC18F4431-I/ML)
- Industrial temperature grade aligned with appliance thermal envelope (vs PIC18F4331-E/ML)
Design Notes
The 44-QFN package uses an exposed thermal pad (pin 45) that MUST be soldered to a continuous ground pour with a minimum of 8 thermal vias (0.3 mm drill, 0.5 mm pitch) for reliable operation at sustained PWM switching loads. Estimated: with the MCU dissipating 0.3W at 40 MIPS and 5V VDD (I_DD approx 25 mA), the theta_JA of approximately 32 (C/W) yields a junction temperature rise of only 10C above ambient. However, when driving high-current PWM outputs into capacitive MOSFET gates, gate-charge losses can push dissipation to 1W, requiring the thermal via pattern to keep Tj below 85C.
Route PWM outputs (pins 33-38) on the top layer with short traces under 25 mm to the gate-driver inputs. Add a 100 nF ceramic bypass capacitor at each VDD/VSS pair (pins 7/8 and 20/21) within 3 mm of the package. Keep the crystal/oscillator traces (RA6/RA7) under 5 mm and isolate them with a ground guard ring to prevent PWM edge coupling into the system clock. The AVDD/AVSS pair (pins 43/44) requires a 10 microhenry ferrite bead and separate analog ground island that joins at a single point near the EP ground pour.
Do not connect the MCLR pin (pin 1) directly to VDD without a pull-up resistor; per Microchip datasheet section 4.0, MCLR requires a 10-50 kohm pull-up to ensure clean reset transitions and to enable in-circuit serial programming. Decoupling: provide at least 1 microfarad of bulk capacitance on VDD within 10 mm of the package, plus 100 nF on each VDD pin. For ICSP programming, route PGC (RB6) and PGD (RB7) directly to the programming header without series resistors - the internal weak pull-ups are sufficient for production use but must be disabled in firmware during high-noise PWM operation.
Compliance Information
RoHS and REACH compliance per Microchip product page and DigiKey environmental data. Not AEC-Q100 qualified - choose PIC18F4331-E/ML (extended temp) for non-automotive industrial, or migrate to a Q-graded PIC18 if AEC-Q100 is required. Halogen-free per Microchip letter of declaration.
