PIC18F4331T-I/ML - 8-bit PIC MCU, 8KB Flash, 44-QFN | Microchip
MPN: PIC18F4331T-I/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.39 | $8.39 |
| 10 | $7.96 | $79.60 |
| 100 | $7.13 | $713.00 |
| 500 | $6.42 | $3,210.00 |
| 1,000 | $5.78 | $5,780.00 |
PIC18F4331T-I/ML Overview
What is a PIC18 microcontroller? The PIC18F family is Microchip's high-performance 8-bit microcontroller line, positioned between the baseline PIC10/12/16 families and the 16-bit dsPIC/PIC24 families. PIC18F devices use an enhanced Harvard architecture with a 16-bit instruction word, 8-bit data path, hardware multiplier, and C-friendly compiler support via MPLAB XC8. They form part of the broader microcontroller category, sitting between 8-bit AVR/8051 derivatives and 32-bit ARM Cortex-M0 cores in performance and power.
Key features include a 14-channel, 10-bit Analog-to-Digital Converter (ADC), three programmable power-managed operating modes (Run, Idle, Sleep) with nanoWatt technology for low-power operation, a high-performance 14-bit PWM module with up to 6 PWM outputs designed for motor control, a Capture/Compare/PWM (CCP) module, an Enhanced USART, MSSP (SPI/I2C), and 34 digital I/O pins. The device supports ICSP (In-Circuit Serial Programming) and ICD (In-Circuit Debugging) via MPLAB tools.
The PIC18F4331 incorporates dedicated motor-control peripherals including a Power Control PWM module with complementary outputs, dead-band control, and fault inputs—making it a true single-chip solution for brushless DC (BLDC), permanent magnet synchronous motor (PMSM), and AC induction motor drives. The architecture includes a hardware multiplier and 32-level stack supporting structured C code with deep call nesting.
Typical applications include three-phase BLDC and PMSM motor controllers, sensorless and sensored motor drives for pumps/fans/HVAC blowers, industrial variable-frequency drives, ceiling fans and small appliances, power tools, and small-format uninterruptible power supplies. The integrated 14-bit PWM reduces BOM by eliminating external PWM generator ICs.
When designing with the PIC18F4331T-I/ML, allocate a ground pad via the exposed pad (EP) on pin 44, which must be soldered to a copper pour for thermal dissipation and electrical grounding. Decouple VDD with 100 nF + 10 uF ceramic capacitors placed within 5 mm of the supply pins. Use the internal 8 MHz oscillator with PLL for 40 MHz operation, or an external crystal for timing-critical motor control loops.
This page synthesizes distributor pricing, drop-in alternatives (PIC18F4331-I/ML, PIC18F4431T-I/ML, PIC18F2331-I/ML and others), and practical design notes not consolidated in the Microchip datasheet.
Drop-in alternatives for PIC18F4331T-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 PIC18F4331T-I/ML (same form factor and footprint) — differing in ADC, Operating Temperature, Package, Communication, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F4331-I/ML
✅ Drop-In✓ In Stock
$5.32 / Unit
View Datasheet →PIC18F4331-E/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4431T-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF4331-I/ML
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18F4431-I/ML
✅ Drop-In✓ In Stock
$4.85 / Unit
View Datasheet →PIC18F4331T-I/ML Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 (8-bit enhanced Harvard, RISC) |
| Program Memory (Flash) | 8 KB |
| Data RAM | 768 bytes |
| Data EEPROM | 256 bytes |
| Maximum Clock Frequency | 40 MHz |
| Supply Voltage (VDD) | 2.0 V to 5.5 V |
| Digital I/O Pins | 34 |
| ADC | 10-bit, up to 9 channels |
| PWM Module | 14-bit Power Control PWM, up to 6 outputs |
| Communication Interfaces | EUSART, MSSP (SPI/I2C) |
| Timers | Timer0/1/2/3, CCP |
| Package | 44-pin QFN (8x8 mm) with exposed pad |
| Operating Temperature | -40C to +85C (Industrial grade) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Programming/Debug | ICSP / ICD via MPLAB tools |
| Low-Power Modes | nanoWatt technology (Run, Idle, Sleep) |
PIC18F4331T-I/ML Pin Configuration
| Pin 1 | RC0/T1OSO/T1CKI — Digital I/O / Timer1 oscillator output / Timer1 clock input |
| Pin 2 | RC1/CCP2 — Digital I/O / Capture Compare PWM 2 |
| Pin 3 | RC2/CCP1/P1A — Digital I/O / CCP1 / PWM1 output A |
| Pin 4 | RC3/T0CKI — Digital I/O / Timer0 clock input |
| Pin 5 | RC4/INT0 — Digital I/O / External interrupt 0 |
| Pin 6 | RC5/INT1 — Digital I/O / External interrupt 1 |
| Pin 7 | RC6/TX/CK — Digital I/O / EUSART TX / clock |
| Pin 8 | RC7/RX/DT — Digital I/O / EUSART RX / data |
| Pin 9 | VSS — Ground reference |
| Pin 10 | VDD — Positive supply voltage |
| Pin 11 | RA0/AN0 — Digital I/O / Analog input 0 |
| Pin 12 | RA1/AN1 — Digital I/O / Analog input 1 |
| Pin 13 | RA2/AN2 — Digital I/O / Analog input 2 |
| Pin 14 | RA3/AN3 — Digital I/O / Analog input 3 |
| Pin 15 | RA4/AN4 — Digital I/O / Analog input 4 (open-drain) |
| Pin 16 | RA5/AN5 — Digital I/O / Analog input 5 |
| Pin 17 | RA6/OSC2/CLKO — Digital I/O / Oscillator output |
| Pin 18 | RA7/OSC1/CLKI — Digital I/O / Oscillator input |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage |
| Pin 21 | RB0/INT0/FLTA — Digital I/O / Interrupt 0 / PWM fault A |
| Pin 22 | RB1/INT1 — Digital I/O / Interrupt 1 |
| Pin 23 | RB2/INT2 — Digital I/O / Interrupt 2 |
| Pin 24 | RB3/INT3 — Digital I/O / Interrupt 3 |
| Pin 25 | RB4/KBI0 — Digital I/O / Keyboard interrupt 0 |
| Pin 26 | RB5/KBI1/PGM — Digital I/O / Keyboard interrupt 1 / LVP program |
| Pin 27 | RB6/KBI2/PGC — Digital I/O / KBI2 / ICSP clock |
| Pin 28 | RB7/KBI3/PGD — Digital I/O / KBI3 / ICSP data |
| Pin 29 | RD0 — Digital I/O port D bit 0 |
| Pin 30 | RD1 — Digital I/O port D bit 1 |
| Pin 31 | RD2 — Digital I/O port D bit 2 |
| Pin 32 | RD3 — Digital I/O port D bit 3 |
| Pin 33 | RD4 — Digital I/O port D bit 4 |
| Pin 34 | RD5/P1B — Digital I/O / PWM1 output B (complementary) |
| Pin 35 | RD6/P1C — Digital I/O / PWM1 output C |
| Pin 36 | RD7/P1D — Digital I/O / PWM1 output D |
| Pin 37 | RE0/AN6 — Digital I/O / Analog input 6 |
| Pin 38 | RE1/AN7 — Digital I/O / Analog input 7 |
| Pin 39 | RE2/AN8 — Digital I/O / Analog input 8 |
| Pin 40 | RE3 — Digital I/O port E bit 3 (input only) |
| Pin 41 | AVDD — Analog positive supply |
| Pin 42 | AVSS — Analog ground reference |
| Pin 43 | NC — Not connected (per datasheet) |
| Pin 44 | EP — Exposed pad - thermal/ground, must be soldered to PCB pad |
Typical Applications
PIC18F4331T-I/ML is suitable for 7 applications: BLDC Motor Control (Brushless DC), PMSM Field-Oriented Control (FOC), HVAC Variable-Frequency Drives, Ceiling Fans and Small Appliances, Industrial Pumps and Fans, Power Tools and Cordless Appliances, Small UPS Systems.
BLDC Motor Control (Brushless DC)
The PIC18F4331T-I/ML is purpose-built for 3-phase BLDC motor control. Its 14-bit Power Control PWM delivers up to 6 complementary outputs with hardware dead-band generation and fault inputs, eliminating external gate-driver logic. The 40 MHz core executes sensorless back-EMF trapezoidal commutation in real time, while the 10-bit ADC samples phase voltages synchronously to the PWM carrier. Engineers implementing ceiling fans, drone propellers, or pump motors benefit from the integrated analog comparators and PWM fault shutdown that protect MOSFET half-bridges during overcurrent events.
Recommended
PMSM Field-Oriented Control (FOC)
Permanent Magnet Synchronous Motor (PMSM) controllers using the PIC18F4331T-I/ML leverage its 40 MHz clock for software-based Park/Clarke transformations and PI current loops. The 14-bit PWM center-aligned mode supports the 20 kHz switching frequencies required for industrial servo drives. With 8 KB Flash and 768 bytes RAM, this part handles sensored FOC for small appliances; engineers needing more headroom for full state observers should migrate to PIC18F4431T-I/ML (16 KB Flash) which is pin-compatible.
Recommended
HVAC Variable-Frequency Drives
HVAC blower and compressor variable-frequency drives use the PIC18F4331T-I/ML as the main control MCU. Its -40C to +85C industrial temperature range tolerates attic and outdoor equipment environments. The nanoWatt Sleep mode reduces standby power to <1 uA, critical for meeting ENERGY STAR idle consumption limits. With 34 I/O pins, the MCU directly interfaces to line-voltage zero-cross detectors, temperature sensors (NTC10K), and IGBT/MOSFET gate drivers without external glue logic, reducing BOM cost in mass-produced HVAC controllers.
Recommended
Ceiling Fans and Small Appliances
Consumer ceiling fans, range hoods, and small appliances integrate the PIC18F4331T-I/ML for quiet, energy-efficient BLDC control. The 14-bit PWM enables sub-1% speed regulation, while the ICSP debug port allows in-field firmware updates through the MPLAB PICkit 5 programmer. The 44-QFN (8x8 mm) package fits within the compact control box constraints typical of ceiling fan canopy housings. Compared with the prior generation PIC16F777-I/ML, this part provides 4x more PWM resolution for quieter motor operation at low speeds.
Recommended
Industrial Pumps and Fans
Industrial centrifugal pumps and exhaust fans deploy the PIC18F4331T-I/ML for closed-loop flow and pressure regulation. The 10-bit ADC accepts 4-20 mA sensor inputs via a shunt resistor, while the 14-bit PWM drives 3-phase IGBT inverters at 8-16 kHz. The hardware QEI (Quadrature Encoder Interface) feedback tracks rotational speed with 4x resolution, enabling precise closed-loop control. Industrial engineers appreciate the 100K Flash endurance rating per the Microchip datasheet, ensuring 10+ years of daily parameter logging in pump stations.
Recommended
Power Tools and Cordless Appliances
Cordless drills, impact drivers, and battery-powered tools use the PIC18F4331T-I/ML for brushless motor control with current limiting and thermal protection. The PWM fault input instantly disables outputs when overcurrent is detected from a current shunt amplifier, protecting both the battery and motor windings. With 8 KB Flash, engineers implement torque limiting, soft-start profiles, and battery-state-of-charge (SoC) estimation in a single chip. The 44-QFN exposed pad aids thermal dissipation in enclosed tool housings operating at up to 50C ambient.
Recommended
Small UPS Systems
Small uninterruptible power supplies (line-interactive UPS, 300-1500 VA) use the PIC18F4331T-I/ML for inverter control, battery management, and AC line synchronization. The EUSART interfaces to RS-232 monitoring, while the MSSP (SPI) connects to battery-monitoring AFE chips. The 14-bit PWM generates the 50/60 Hz sinewave inverter output with proper harmonic distortion limits. The MCU's industrial -40C to +85C range suits battery cabinet environments where temperatures can exceed 60C during heavy discharge.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F4331T-I/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4331-I/ML | PIC18F4331-E/ML | PIC18F4431T-I/ML | PIC18LF4331-I/ML |
|---|---|---|---|---|---|
| Package | 44-QFN (8x8) with EP | 44-QFN (8x8) - same | 44-QFN (8x8) - same | 44-QFN (8x8) - same | 44-QFN (8x8) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 8 KB | 8 KB | 8 KB | 16 KB | 8 KB |
| RAM | 768 B | 768 B | 768 B | 1024 B | 768 B |
| EEPROM | 256 B | 256 B | 256 B | 256 B | 256 B |
| Max Clock Frequency | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz |
| Operating Voltage | 4.2 V to 5.5 V (F) | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 2.0 V to 5.5 V |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C | -40C to +125C (Extended) | -40C to +85C | -40C to +85C |
| Digital I/O Pins | 34 | 34 | 34 | 34 | 34 |
| PWM Resolution | 14-bit | 14-bit | 14-bit | 14-bit | 14-bit |
Key Differentiators
- Integrated 14-bit Power Control PWM with hardware fault inputs (vs PIC16F777-I/ML)
- Flash doubles when migrating to PIC18F4431T-I/ML (drop-in upgrade) (vs PIC18F4431T-I/ML)
- nanoWatt low-power modes reduce standby to <1 uA (vs PIC16F777-I/ML)
Design Notes
The 44-QFN package exposes its die through the EP (Exposed Pad) on pin 44. Solder this pad to a PCB copper pour of at least 100 mm^2 to maintain junction temperature below 85C at 40 MHz operation across the industrial temperature range. Estimated thermal resistance theta_JA on a 4-layer JEDEC test board is approximately 30 C/W; without the EP soldered, junction temperature can rise 40-50C above ambient at full CPU load.
Place 100 nF ceramic decoupling capacitors on every VDD/AVDD pin pair within 5 mm of the IC, plus one bulk 10 uF tantalum or ceramic capacitor at the board entry point. Separate analog AVDD/AVSS from digital VDD/VSS with ferrite beads for ADC accuracy; the 10-bit ADC requires clean analog supply to achieve 1 LSB noise performance per the PIC18F4331 datasheet. Estimated: total decoupling BOM cost is under $0.10 per board.
Route the ICSP clock (PGC) and data (PGD) lines on the top layer with a ground reference plane underneath, avoiding vias and keeping them under 50 mm trace length. Place the 4-pin ICSP header at the board edge to allow MPLAB PICkit 5 access without removing the MCU from the board. The exposed pad (pin 44) MUST be soldered; use a 0.5 mm pitch stencil aperture pattern with 50% solder paste coverage to avoid voids.
Do not confuse the PIC18F4331 (4.2-5.5 V) with the PIC18LF4331 (2.0-5.5 V). At 3.3 V supply, only the LF variant operates correctly. Configuration bits must be programmed for the correct oscillator mode (HS for >8 MHz crystal, INTOSC for internal 8 MHz with PLL to 40 MHz). Forgetting the PLL configuration leaves the MCU at 8 MHz, causing PWM carrier frequency errors that destabilize motor control loops. Use MPLAB X IDE's code configurator to set configuration bits correctly.
For motor-control applications, route PWM outputs (P1A-P1D) and the FLTA fault input away from analog ADC traces to prevent switching noise coupling. Use series ferrite beads on motor supply lines and keep ADC traces differential when measuring current shunts. The 14-bit PWM outputs can generate 2-3 ns edge rates; add 22-33 ohm source-series termination if the trace length exceeds 25 mm to the gate driver.
Compliance Information
RoHS compliant per Microchip product page (PIC18F4331 family). Not AEC-Q100 qualified; for automotive motor control, consider PIC18F4431-E/ML or dsPIC33 variants with explicit automotive qualification. Industrial -40C to +85C temperature grade.
