PIC18LF2331-I/MM - 8-bit 40MHz 8KB Flash MCU 28-QFN | Microchip
MPN: PIC18LF2331-I/MM ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.83 | $5.83 |
| 10 | $5.25 | $52.50 |
| 100 | $4.66 | $466.00 |
| 500 | $4.08 | $2,040.00 |
| 1,000 | $3.49 | $3,490.00 |
PIC18LF2331-I/MM Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, working RAM, peripherals and I/O on one die; the PIC18 family uses an enhanced Harvard RISC architecture with 16-bit opcodes, separate program and data buses, and a hardware multiply unit, giving roughly 10 MIPS at 40 MHz. Within the broader taxonomy, a microcontroller is a sub-class of microprocessor, and the PIC18LF2331 specifically targets motor-control and mixed-signal embedded roles where deterministic timing, on-chip ADC and PWM matter more than raw clock speed.
Key features of this part include the 40 MHz core clock, 8 KB Flash, 25 digital I/O pins, an on-chip 10-bit ADC, multiple PWM/capture/compare modules suitable for motor-control loops, and the nanoWatt low-power feature set with multiple idle/sleep modes. The device offers 256 bytes of EEPROM data memory, an internal RC oscillator, and a wide industrial operating temperature range of -40 °C to +85 °C, all in the compact 28-QFN-S (6x6 mm) outline.
The architecture uses a 16-bit instruction word with 8-bit data path, a hardware stack of 31 levels and 75+ instruction set, plus nanoWatt dynamic power management that scales core current with clock speed. Peripheral highlights include a 10-bit ADC with multiple input channels, capture/compare/PWM (CCP) and enhanced CCP modules, two USART modules, an MSSP (SPI/I2C) port, and timers that can drive brushless-DC or stepper motor commutation directly without an external controller.
Typical applications for the PIC18LF2331-I/MM include sensor-less and sensored BLDC motor control, small stepper-motor drives, industrial fan/pump controllers, white-goods appliance controls, HVAC actuators, and general-purpose low-power embedded nodes. The exposed thermal pad QFN package helps dissipate switching losses in PWM-heavy motor-control stages.
When designing with this MCU, note that pin remapping is limited on the 28-QFN variant versus larger 40/44-pin family members, so verify the alternate-function map before assigning PWM, ADC and UART pins. Always provide a decoupling capacitor pair (100 nF + bulk) directly at VDD/VSS and bond the exposed pad to a ground copper pour for thermal and EMI performance.
This page consolidates distributor stock data, pin-to-pin drop-in alternatives and practical design notes that go beyond the manufacturer datasheet, helping you select and qualify the PIC18LF2331-I/MM for volume production.
Drop-in alternatives for PIC18LF2331-I/MM — 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 PIC18LF2331-I/MM (same form factor and footprint) — differing in Operating Temperature, Package, Mounting Type, ADC, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F2331-I/MM
✅ Drop-In✓ In Stock
$3.15 / Unit
View Datasheet →PIC18LF2431-I/MM
✅ Drop-In✓ In Stock
$3.05 / Unit
View Datasheet →PIC18LF4331-I/MM
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF4431-I/MM
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF2331-I/MM Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 (8-bit Harvard RISC) |
| Core Clock Speed | 40 MHz (max) |
| Program Memory (Flash) | 8 KB (4K x 16) |
| Data EEPROM | 256 bytes |
| Supply Voltage (LF) | 2.5 V / 3.3 V / 5 V |
| Operating Temperature | -40 °C to +85 °C (Industrial) |
| Digital I/O Pins | 25 |
| On-chip ADC | 10-bit |
| PWM / CCP Modules | Yes (CCP + ECCP) |
| Communication Peripherals | USART, MSSP (SPI/I2C) |
| Package | 28-QFN-S EP (6x6 mm), exposed pad |
| Mounting Type | Surface Mount |
| Power-Saving Features | nanoWatt Technology (multiple idle/sleep modes) |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC18LF2331-I/MM Pin Configuration
| Pin 1 | MCLR/RE3 — Master Clear (reset) input or digital I/O RE3 |
| Pin 2 | OSC1/CLKIN/RA7 — Oscillator input / external clock / GPIO RA7 |
| Pin 3 | OSC2/CLKOUT/RA6 — Oscillator output / clock out / GPIO RA6 |
| Pin 4 | RA0/AN0 — GPIO RA0 / analog input AN0 |
| Pin 5 | RA1/AN1 — GPIO RA1 / analog input AN1 |
| Pin 6 | RA2/AN2/VREF- — GPIO RA2 / AN2 / ADC VREF- |
| Pin 7 | RA3/AN3/VREF+ — GPIO RA3 / AN3 / ADC VREF+ |
| Pin 8 | RA4/AN4 — GPIO RA4 / AN4 (open-drain) |
| Pin 9 | RA5/AN5 — GPIO RA5 / AN5 |
| Pin 10 | VSS — Ground reference |
| Pin 11 | VDD — Positive supply voltage (2.5/3.3/5 V) |
| Pin 12 | RB0/AN8/INT0 — GPIO RB0 / AN8 / external interrupt 0 |
| Pin 13 | RB1/AN9/INT1 — GPIO RB1 / AN9 / external interrupt 1 |
| Pin 14 | RB2/AN10/INT2 — GPIO RB2 / AN10 / external interrupt 2 |
| Pin 15 | RB3/AN11 — GPIO RB3 / AN11 |
| Pin 16 | RB4 — GPIO RB4 (interrupt-on-change) |
| Pin 17 | RB5 — GPIO RB5 (interrupt-on-change) |
| Pin 18 | RB6/PGC — GPIO RB6 / ICD clock (PGC) |
| Pin 19 | RB7/PGD — GPIO RB7 / ICD data (PGD) |
| Pin 20 | RC0/T1OSO — GPIO RC0 / Timer1 oscillator output |
| Pin 21 | RC1/T1OSI/CCP2 — GPIO RC1 / T1OSI / CCP2 |
| Pin 22 | RC2/CCP1 — GPIO RC2 / CCP1 PWM output |
| Pin 23 | RC3 — GPIO RC3 |
| Pin 24 | RC4 — GPIO RC4 |
| Pin 25 | RC5 — GPIO RC5 |
| Pin 26 | RC6/TX/CK — GPIO RC6 / USART TX or clock |
| Pin 27 | RC7/RX/DT — GPIO RC7 / USART RX or data |
| Pin 28 | VSS — Ground reference (second VSS pin) |
| Pin 29 | EP — Exposed thermal pad - tie to ground |
Typical Applications
PIC18LF2331-I/MM is suitable for 6 applications: Sensor-less BLDC Motor Control, Industrial Fan and Pump Controllers, White-Goods Appliance Control Boards, HVAC Actuator and Damper Control, Battery-Powered Sensor Nodes, General-Purpose Stepper Motor Driver.
Sensor-less BLDC Motor Control
The PIC18LF2331-I/MM fits sensor-less BLDC motor control because its 40 MHz PIC18 core executes commutation loops in well under 50 microseconds, while the on-chip 10-bit ADC and ECCP PWM modules drive the three-phase inverter directly. According to the Microchip PIC18F2331/4331 datasheet, the dedicated motor-control PWM and integrated quadrature encoder interface eliminate external commutation logic. Compared with a discrete MCU + gate-driver design, this single-chip approach cuts BOM cost, and the wide 2.5 V to 5 V supply lets the board run from a 3.3 V buck or a 5 V USB input. Place decoupling caps at VDD/VSS and bond the 28-QFN-S exposed pad to ground copper for thermal relief under continuous PWM switching.
Recommended
Industrial Fan and Pump Controllers
The PIC18LF2331-I/MM is a strong fit for industrial fan and pump controllers, where its 8 KB Flash holds closed-loop speed profiles, its nanoWatt sleep modes cut idle current below 1 microampere for standby operation, and its industrial -40 °C to +85 °C range tolerates harsh factory cabinets. The 10-bit ADC samples tachometer or pressure transducer signals at high rates, while the ECCP PWM generates variable-frequency drives for the motor. Versus a polling-only design, the hardware interrupt latency of the PIC18 keeps the control loop deterministic. Use a 100 nF + 10 uF decoupling pair and route PWM traces away from ADC inputs to avoid switching noise coupling.
Recommended
White-Goods Appliance Control Boards
In washing machines, dishwashers and refrigerators, the PIC18LF2331-I/MM acts as the main controller, using its 25 digital I/O pins to drive relays, sense door interlocks and read keypad/touch inputs. The 40 MHz core handles encoder feedback from the BLDC drum motor, while the wide voltage range accepts 5 V or 3.3 V rails after rectification. Compared with an 8-bit 8051 design, the PIC18 instruction set is shorter and the interrupt structure is more flexible, reducing firmware complexity. The exposed-pad 28-QFN-S package improves thermal performance in enclosed appliance cavities, and the industrial temperature grade handles under-cabinet heat reliably.
Recommended
HVAC Actuator and Damper Control
HVAC systems use the PIC18LF2331-I/MM to drive small BLDC actuators that open and close air dampers, modulate chilled-water valves and run variable-speed fans. The PIC18's hardware PWM modules generate accurate servo-style control signals, while the 10-bit ADC reads thermistor feedback from supply and return air streams. Compared with analog op-amp controllers, the MCU adds software-defined control curves that can be tuned per installation without hardware rework. The industrial temperature range handles plenum heat, and the small 28-QFN-S package fits inside compact damper housings. Validate ADC accuracy over temperature and add RC filtering on analog inputs to suppress HVAC line noise.
Recommended
Battery-Powered Sensor Nodes
Low-power wireless sensor nodes benefit from the PIC18LF2331-I/MM's nanoWatt technology: idle current drops to microampere levels, and the wide 2.5 V to 5 V supply allows direct connection to two AA cells or a Li-ion battery without a boost converter. The MCU wakes on a timer interrupt, samples a sensor via the 10-bit ADC, transmits a packet and returns to sleep, achieving months of battery life. Compared with a 32-bit ARM MCU, the 8-bit PIC18 draws far less quiescent current and offers predictable wake-time latency. Use low-leakage discrete sensors and disable unused peripherals in firmware to maximize runtime on each battery change.
Recommended
General-Purpose Stepper Motor Driver
The PIC18LF2331-I/MM controls bipolar stepper motors used in 3D printers, CNC Z-axis stages and laboratory automation by generating accurate step/direction pulses and current-chopping references via its CCP/ECCP modules. The 8 KB Flash stores acceleration ramps in lookup tables, and the 40 MHz core computes microstep waveforms in real time. Compared with discrete stepper controllers, the integrated MCU eliminates an external driver IC for low-current axes. The 28-QFN-S package keeps the board footprint compact, and the exposed pad dissipates heat from constant PWM chopping. Implement overcurrent detection via the ADC and software-limited step rates to protect motor windings.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF2331-I/MM — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F2331-I/MM | PIC18LF2431-I/MM | PIC18LF4331-I/MM | PIC18LF4431-I/MM |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-QFN-S (6x6 mm) | 28-QFN-S (6x6 mm) - same | 28-QFN-S (6x6 mm) - same | 28-QFN-S (6x6 mm) - same | 28-QFN-S (6x6 mm) - same |
| Supply Voltage | 2.5 / 3.3 / 5 V | 4.2-5.5 V | 2.5 / 3.3 / 5 V | 2.5 / 3.3 / 5 V | 2.5 / 3.3 / 5 V |
| Core Clock | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz |
| Flash Program Memory | 8 KB | 8 KB | 16 KB | 8 KB | 16 KB |
| EEPROM | 256 B | 256 B | 256 B | 256 B | 256 B |
| Digital I/O Pins | 25 | 25 | 25 | 36 | 36 |
| ADC | 10-bit | 10-bit | 10-bit | 10-bit | 10-bit |
| Operating Temperature | -40 to +85 °C | -40 to +85 °C | -40 to +85 °C | -40 to +85 °C | -40 to +85 °C |
Key Differentiators
- Wide 2.5/3.3/5 V supply versus 5 V only on PIC18F2331 (vs PIC18F2331-I/MM)
- Larger Flash upgrade within same package (vs PIC18LF2431-I/MM)
- More I/O and PWM channels in same outline (vs PIC18LF4331-I/MM)
Design Notes
Estimated: at VDD=3.3 V and 40 MHz active core with all peripherals enabled, the PIC18LF2331-I/MM draws roughly 15-20 mA; in sleep mode this drops to microampere levels thanks to nanoWatt technology. Place a 100 nF ceramic decoupling capacitor within 3 mm of VDD (pin 11) and a 10 uF bulk capacitor on the same rail. For battery-powered designs, drive the MCLR pin through a 10 kohm pull-up so that the nanoWatt sleep current is not wasted through a floating reset line.
The 28-QFN-S package requires the exposed thermal pad (pin 29) to be soldered to a ground copper pour that is at least 1 square inch for thermal relief under PWM switching. Thermal vias in a 3x3 grid under the EP significantly improve heat dissipation. Route ADC analog traces away from PWM outputs and clock lines to avoid switching-noise coupling, and keep the OSC1/OSC2 crystal traces short and symmetric to minimize EMI.
A common pitfall on the PIC18LF2331 is forgetting that AN8-AN11 share pins with RB0-RB3, so enabling the ADC on those channels disables digital I/O on the same pins. Another frequent mistake is using the internal RC oscillator at full 40 MHz without verifying the temperature stability across the industrial -40 °C to +85 °C range; for time-critical UART or PWM applications, use an external 10 MHz crystal with the PLL enabled. Finally, do not omit the ICD clock and data pull-ups on RB6/RB7 - the debugger needs them for in-circuit programming.
Estimated: at 40 MHz Fosc, the PIC18LF2331's GPIO edges are roughly 10 ns rise time, so place a 33 ohm series resistor on PWM outputs driving long cables or motor windings to damp reflections. The ADC inputs are sensitive to PWM switching noise; add a 100 ohm + 1 nF RC filter on analog channels that run parallel to switching nodes. For BLDC applications, keep the three-phase PWM traces matched in length to within 2 mm to balance switching delays.
