PIC18LF2331-I/SO - 8-bit 40MHz MCU 8KB Flash 22 I/O | Microchip
MPN: PIC18LF2331-I/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.27 | $7.27 |
| 10 | $6.62 | $66.20 |
| 100 | $5.98 | $598.00 |
| 500 | $5.43 | $2,715.00 |
| 1,000 | $4.88 | $4,880.00 |
PIC18LF2331-I/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, non-volatile program memory, working RAM, and configurable digital and analog peripherals. The PIC18 family is Microchip's 8-bit enhanced architecture, sitting between the baseline PIC10/12/16 families and the 16-bit dsPIC/PIC24 families. 8-bit PIC MCUs are widely used in cost-sensitive and deterministic control applications where simplicity, low power, and predictable interrupt latency matter more than raw computation throughput.
Key features include a 10-bit ADC with up to 5 channels (depending on package), a CCP/ECCP module for PWM and capture/compare, an Enhanced USART, an MSSP module for SPI and I2C, a 10 MHz internal oscillator, and nanoWatt technology for low-power sleep modes with current draw below 100 nA. The 40 MHz MIPS rate delivers 10 MIPS of throughput, supporting real-time closed-loop control loops and protocol handling.
Architecturally, the PIC18LF2331 uses a Harvard RISC core with separate program and data buses, a 16-bit instruction word, and hardware multiply. The Flash-based program memory supports in-circuit serial programming (ICSP) and Microchip's self-programming bootloader, enabling field firmware updates without an external programmer.
Typical applications include HVAC fan and pump control, small appliance motor drives (especially brushless DC using the ECCP module), industrial sensor interfaces, low-cost consumer white goods, battery-powered instrumentation, and automotive body/comfort subsystems. The wide 2.0 V to 5.5 V range also lets it run directly from a single-cell Li-ion or two AA cells.
When designing with this part, validate that your chosen CCP/PWM frequency, ADC sampling rate, and instruction cycle budget fit within 10 MIPS. Place a 100 nF decoupling capacitor within 5 mm of VDD, and reserve the ICSP pins (RB6/RB7) for in-circuit programming access on the production PCB.
This page synthesizes distributor pricing, drop-in PIC18LF2321/PIC18F2331 family alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC18LF2331-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 PIC18LF2331-I/SO (same form factor and footprint) — differing in Package, Operating Temperature, Core Architecture, MSL Level, ADC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18LF2321-I/SO
✅ Drop-In✓ In Stock
$2.4 / Unit
View Datasheet →PIC18F2331-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF2331-I/SP
✅ Drop-In✓ In Stock
$3.85 / Unit
View Datasheet →PIC18LF2431-I/SO
✅ Drop-In✓ In Stock
$3.1 / Unit
View Datasheet →PIC18LF2331T-I/SO
✅ Drop-In✓ In Stock
$4.1 / Unit
View Datasheet →PIC18F2431-I/SO
✅ Drop-In✓ In Stock
$4.85 / Unit
View Datasheet →PIC18LF2331-I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 (8-bit Harvard RISC) |
| Program Memory | 8 KB Flash (4K x 16) |
| Data SRAM | 768 bytes |
| Data EEPROM | 256 bytes |
| Maximum Clock Frequency | 40 MHz |
| Instruction Throughput | 10 MIPS |
| Supply Voltage (VDD) | 2.0 V to 5.5 V |
| I/O Pins | 22 |
| ADC | 10-bit, up to 5 channels |
| PWM/CCP Modules | 1 ECCP + 2 CCP |
| Communication Peripherals | 1x EUSART, 1x MSSP (SPI/I2C) |
| Timers | 4 (Timer0/1/2/3) |
| Package | 28-pin SOIC (SO) |
| Operating Temperature | -40 °C to +85 °C (Industrial) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited floor life at <30 °C / 85 % RH) |
| RoHS Status | Compliant (lead-free SO package) |
| Low-Power Modes | nanoWatt (sleep current <100 nA typical) |
| In-Circuit Programming | ICSP via RB6/RB7 |
PIC18LF2331-I/SO Pin Configuration
| Pin 1 | MCLR — Master Clear (reset) input, internal pull-up, ICSP programming voltage |
| Pin 2 | RA0/AN0 — Digital I/O / analog input channel 0 |
| Pin 3 | RA1/AN1 — Digital I/O / analog input channel 1 |
| Pin 4 | RA2/AN2/VREF- — Digital I/O / analog input channel 2 / ADC negative reference |
| Pin 5 | RA3/AN3/VREF+ — Digital I/O / analog input channel 3 / ADC positive reference |
| Pin 6 | RA4/T0CKI — Digital I/O / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — Digital I/O / analog input channel 4 / SPI slave select |
| Pin 8 | RE0/RD/AN5 — Digital I/O / parallel slave port read / analog input channel 5 |
| Pin 9 | OSC1/CLKI — External crystal/clock input |
| Pin 10 | OSC2/CLKO/RA6 — Crystal driver output / clock output / digital I/O |
| Pin 11 | RC0/T1OSO/T13CKI — Digital I/O / Timer1 oscillator output / Timer1/Timer3 clock |
| Pin 12 | RC1/T1OSI/CCP2 — Digital I/O / Timer1 oscillator input / CCP2 PWM output |
| Pin 13 | RC2/CCP1 — Digital I/O / CCP1 PWM output |
| Pin 14 | RC3/SCK/SCL — Digital I/O / SPI clock / I2C clock |
| Pin 15 | RC4/SDI/SDA — Digital I/O / SPI data in / I2C data |
| Pin 16 | RC5/SDO — Digital I/O / SPI data out |
| Pin 17 | RC6/TX/CK — Digital I/O / EUSART asynchronous transmit / synchronous clock |
| Pin 18 | RC7/RX/DT — Digital I/O / EUSART asynchronous receive / synchronous data |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply (2.0 V to 5.5 V) |
| Pin 21 | RB0/INT0 — Digital I/O / external interrupt 0 |
| Pin 22 | RB1/INT1 — Digital I/O / external interrupt 1 |
| Pin 23 | RB2/INT2 — Digital I/O / external interrupt 2 |
| Pin 24 | RB3/CCP2A — Digital I/O / enhanced CCP2 PWM output A |
| Pin 25 | RB4 — Digital I/O / interrupt-on-change |
| Pin 26 | RB5 — Digital I/O / interrupt-on-change |
| Pin 27 | RB6/PGC — Digital I/O / interrupt-on-change / ICSP serial clock |
| Pin 28 | RB7/PGD — Digital I/O / interrupt-on-change / ICSP serial data |
Typical Applications
PIC18LF2331-I/SO is suitable for 6 applications: HVAC Fan and Pump Motor Control, Small Appliance BLDC / Brushed DC Drive, Industrial Sensor Interface / Signal Conditioning, Battery-Powered Portable Instrumentation, Automotive Body and Comfort Subsystems, Low-Cost Consumer White Goods.
HVAC Fan and Pump Motor Control
The PIC18LF2331-I/SO suits HVAC fan and pump motor control because its ECCP module generates the complementary PWM outputs needed for 6-step commutation of small three-phase BLDC motors, while the 10-bit ADC samples back-EMF or shunt-current signals in real time. The 40 MHz / 10 MIPS throughput leaves 200+ instruction cycles per PWM period at 20 kHz, enough to run a sensorless start-up ramp and PI current loop without missing a cycle. The 2.0 V to 5.5 V supply range lets the same board operate from a 24 VAC rectified bus with an LDO or from a single-cell Li-ion backup, and 22 I/O pins drive three low-side gate signals, a tachometer input, and a UART to the system controller without multiplexer overhead.
Recommended
Small Appliance BLDC / Brushed DC Drive
Blenders, hand-mixers, fans, and e-bike controllers benefit from the PIC18LF2331-I/SO's deterministic interrupt response and integrated ECCP/CCP PWM channels. With three CCP channels the firmware can implement either single-shunt brushless-DC commutation or sign-magnitude brushed-DC control directly, eliminating the external gate-driver logic that an MCU-less design would need. The 8 KB Flash accommodates speed-loop, soft-start, and protection state machines, while 768-byte SRAM keeps a 2 kHz control loop in on-chip memory without bus contention. The wide 2.0 V to 5.5 V VDD range also simplifies the battery-pack design on cordless appliances that swap between Li-ion and NiMH chemistries.
Recommended
Industrial Sensor Interface / Signal Conditioning
Industrial 4-20 mA loop transmitters, RTD conditioners, and bridge-sensor front-ends use the PIC18LF2331-I/SO for on-chip ADC, EEPROM calibration storage, and EUSART-based HART or RS-485 output. The 10-bit ADC with up to 5 channels handles thermocouple, RTD, or strain-gauge inputs, while the 256-byte data EEPROM retains factory calibration coefficients across power cycles without external serial EEPROM. The MSSP SPI/I2C peripheral interfaces to ADC front-ends, DAC trim chips, or isolated digital isolators, and 40 MHz of headroom runs linearisation, filtering, and protocol framing simultaneously. The -40 °C to +85 °C industrial range and 2.0 V to 5.5 V supply suit harsh 24 V industrial bus rails after a small LDO.
Recommended
Battery-Powered Portable Instrumentation
Handheld multimeters, portable gas detectors, and digital thermometers use the PIC18LF2331-I/SO because of its nanoWatt sleep mode drawing under 100 nA and its 2.0 V VDD operation from two AA cells. The 40 MHz active mode runs the measurement cycle quickly enough to spend most of the duty cycle in sleep, extending battery life by 10x over an always-on design. The 256-byte EEPROM stores user preferences and last-reading memory, while the EUSART drives a low-power LCD or BLE module for wireless readout. Brown-out reset and the wide operating voltage protect against the droop of end-of-life alkaline cells without needing an external supervisor.
Recommended
Automotive Body and Comfort Subsystems
Automotive body controllers for window lift, mirror adjust, seat control, and interior lighting can use the PIC18LF2331-I/SO for cost-sensitive nodes that do not require the full automotive temperature grade of -40 °C to +125 °C. The industrial -40 °C to +85 °C range covers cabin and trunk environments, while the 2.0 V to 5.5 V supply tolerates cranking transients on 12 V bus rails after filtering. The EUSART provides LIN bus connectivity via a LIN transceiver, the MSSP drives I2C sensors and LED drivers, and the ECCP module fades interior lighting with hardware PWM without CPU overhead. The wide Flash and EEPROM support LIN Node Capability 1.3, 2.0, and J2602 stacks.
Recommended
Low-Cost Consumer White Goods
Microwave ovens, rice cookers, induction cooktops, and small washing machines integrate the PIC18LF2331-I/SO for user-interface handling, sensor polling, and discrete output control. The 22 I/O pins drive 7-segment LED displays directly via charlieplexing, read capacitive-touch pads through the ADC, and switch triacs for heater or mains-load control. The Flash and EEPROM store user presets, cooking profiles, and error logs without external memory, while the ICSP interface supports field firmware updates through a service-mode header. The 40 MHz core runs the PID control loop for induction heating in software, avoiding a dedicated DSP.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF2331-I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18LF2321-I/SO | PIC18F2331-I/SO | PIC18LF2331-I/SP | PIC18LF2431-I/SO | PIC18LF2331T-I/SO | PIC18F2431-I/SO |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-pin SOIC | 28-pin SOIC | 28-pin SOIC | 28-pin SPDIP | 28-pin SOIC | 28-pin SOIC | 28-pin SOIC |
| Program Memory (Flash) | 8 KB | 6 KB | 8 KB | 8 KB | 16 KB | 8 KB | 16 KB |
| Data SRAM | 768 bytes | 512 bytes | 768 bytes | 768 bytes | 1 KB | 768 bytes | 1 KB |
| Data EEPROM | 256 bytes | 256 bytes | 256 bytes | 256 bytes | 256 bytes | 256 bytes | 256 bytes |
| Maximum Clock Frequency | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz |
| Supply Voltage (VDD) | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 4.2 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 4.2 V to 5.5 V |
| I/O Pins | 22 | 22 | 22 | 22 | 22 | 22 | 22 |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C |
Key Differentiators
- Low-voltage 2.0 V to 5.5 V VDD operation versus the standard PIC18F family at 4.2 V to 5.5 V (vs PIC18F2331-I/SO)
- Same peripheral map as PIC18LF2321-I/SO but with 33 % more Flash (vs PIC18LF2321-I/SO)
- Half the memory of PIC18LF2431-I/SO at a lower cost (vs PIC18LF2431-I/SO)
Design Notes
Place a 100 nF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 20) and a bulk 10 uF tantalum or aluminium polymer capacitor on the same node. The PIC18LF2331-I/SO draws brief transients during Flash programming and ECCP PWM switching that the bulk cap must supply without VDD droop. Add a 10 kohm pull-up at /MCLR (pin 1) to ensure clean reset during power-up ramp.
Do not confuse the PIC18LF2331 (2.0 V to 5.5 V) with the PIC18F2331 (4.2 V to 5.5 V): firmware that runs on the LF variant will brown-out below 2.0 V on the standard F variant. The 'I' suffix denotes -40 °C to +85 °C industrial temperature, not 'instant' or 'in-circuit'. The 28-pin SOIC package has no SO pin pitch - this is the 300-mil (7.5 mm body width) SOIC, sometimes written SO-28.
Reserve RB6 (pin 27) and RB7 (pin 28) for ICSP serial clock and data. Pull-up resistors on these pins help but can slow programming edges below the PICkit 4 / ICD 3 timing spec - use 10 kohm or weaker. Keep analog traces (RA0-RA5) away from PWM switching nodes (RC1/RC2/CCP) and route the analog VREF separately to avoid ADC reference noise coupling.
The internal 10 MHz oscillator is factory calibrated to within +/-1 % at 25 °C and +/-2 % over -40 °C to +85 °C, sufficient for UART baud rates up to 38.4 kbps at 5 V. For 115.2 kbps UART or LIN bus timing, use an external 40 MHz crystal on OSC1/OSC2 (pins 9 and 10) with 15-33 pF load capacitors. Long OSC traces (over 10 mm) must be guarded with a ground pour to avoid coupling into the ADC.
Compliance Information
RoHS-compliant lead-free SO package per Microchip product page. Industrial -40 °C to +85 °C operating range, not AEC-Q100 qualified - choose PIC18F2331 automotive-grade parts for AEC-Q100 requirements.
