PIC18LF2221-I/SP - 8-Bit 40MHz 4KB Flash MCU | Microchip
MPN: PIC18LF2221-I/SP ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.08 | $4.08 |
| 10 | $3.82 | $38.20 |
| 100 | $3.45 | $345.00 |
| 500 | $3.12 | $1,560.00 |
| 1,000 | $2.78 | $2,780.00 |
PIC18LF2221-I/SP Overview
What is a PIC18 microcontroller? The PIC18 family is Microchip's high-performance 8-bit RISC architecture microcontroller line, belonging to the broader category of microcontrollers (MCU) within the embedded system semiconductor hierarchy: MCU -> microcontroller -> embedded processor -> semiconductor. The PIC18F/LF subfamily adds enhanced Flash memory, nanoWatt power management peripherals, and 10-bit analog-to-digital converters (ADC), bridging legacy PIC16 designs with modern low-power applications.
Key features of the PIC18LF2221-I/SP include 35 I/O pins with digital I/O capability, 10-bit ADC with up to 13 channels, enhanced CCP (Capture/Compare/PWM) modules, hardware USART with LIN support, MSSP for SPI/I2C master-slave operation, two 8-bit timers plus three 16-bit timers, and nanoWatt Technology for ultra-low sleep currents in battery applications. The wide operating voltage range of 2.0V to 5.5V supports both 3.3V and 5V system designs.
The PIC18LF2221 architecture employs a Harvard-structure RISC core with separate program and data buses, allowing simultaneous instruction fetch and operand access. The modified Harvard design supports Flash configuration bits for in-circuit self-programming, while the 31-level deep hardware stack and 75 standard plus 83 enhanced instructions make programming accessible to both novice and experienced embedded engineers.
Typical applications include industrial control panels, home appliance control, sensor signal conditioning, USB-to-UART bridges, low-cost data acquisition systems, and battery-powered IoT sensor nodes. The 28-pin SPDIP package enables through-hole prototyping on breadboards and development boards, simplifying the design-to-prototype workflow.
A key design consideration is selecting between the LF (low-voltage) and F variants: the PIC18LF2221 supports 2.0V to 5.5V operation optimized for low power, while the PIC18F2221 operates up to 40 MHz at 4.2V-5.5V. Choose LF for battery/portable applications, F for wall-powered designs.
This page synthesizes distributor pricing, drop-in pin-compatible alternatives, and practical design notes not found on the manufacturer datasheet front page.
Drop-in alternatives for PIC18LF2221-I/SP — 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 PIC18LF2221-I/SP (same form factor and footprint) — differing in Package, Timers, Core Architecture, Mounting Type, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F2221-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF2220-I/SP
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →PIC18F2320-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
ATMEGA8-16PU
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC18LF14K22-I/P
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.62 / Unit
View Datasheet →PIC18LF2221-I/SP Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 8-bit RISC (Harvard) |
| Program Memory | 4 KB Flash (2K x 16) |
| Data Memory (SRAM) | 512 bytes |
| EEPROM Data Memory | 256 bytes |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Operating Voltage Range | 2.0 V to 5.5 V |
| I/O Pins | 25 |
| ADC | 10-bit, up to 13 channels |
| Timers | 2 x 8-bit, 3 x 16-bit |
| Communication | EUSART, MSSP (SPI/I2C) |
| PWM Channels | Enhanced CCP (ECCP) |
| Operating Temperature | -40C to +85C (Industrial) |
| Package | 28-pin SPDIP (Skinny PDIP) |
| Mounting Type | Through-Hole (THT) |
| Instruction Set | 75 standard + 83 enhanced instructions |
| Stack Depth | 31 levels hardware |
| RoHS Status | Compliant |
PIC18LF2221-I/SP Pin Configuration
| Pin 1 | /MCLR — Master Clear (Reset) input, active low |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input channel 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input channel 1 |
| Pin 4 | RA2/AN2/VREF- — PORTA bit 2 / Analog input channel 2 / ADC VREF- |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input channel 3 / ADC VREF+ |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / Analog input 4 / SPI slave select |
| Pin 8 | OSC1/CLKI — Oscillator input / External clock input |
| Pin 9 | OSC2/CLKO — Oscillator output / External clock output |
| Pin 10 | INT0/RB0 — External interrupt 0 / PORTB bit 0 |
| Pin 11 | VDD — Positive supply voltage (2.0V-5.5V) |
| Pin 12 | VSS — Ground reference |
| Pin 13 | RB1/INT1 — PORTB bit 1 / External interrupt 1 |
| Pin 14 | RB2/INT2 — PORTB bit 2 / External interrupt 2 |
| Pin 15 | RB3/CCP2 — PORTB bit 3 / Capture Compare PWM 2 |
| Pin 16 | RB4 — PORTB bit 4 (interrupt-on-change) |
| Pin 17 | RB5 — PORTB bit 5 (interrupt-on-change) |
| Pin 18 | RB6/PGC — PORTB bit 6 / ICSP clock (ICD clock) |
| Pin 19 | RB7/PGD — PORTB bit 7 / ICSP data (ICD data) |
| Pin 20 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator out / Timer1 clock in |
| Pin 21 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator in / CCP2 |
| Pin 22 | RC2/CCP1 — PORTC bit 2 / Capture Compare PWM 1 |
| Pin 23 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 24 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 25 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 26 | RC6/TX/CK — PORTC bit 6 / EUSART TX / EUSART clock |
| Pin 27 | RC7/RX/DT — PORTC bit 7 / EUSART RX / EUSART data |
| Pin 28 | VSS — Ground reference |
Typical Applications
PIC18LF2221-I/SP is suitable for 6 applications: Industrial Control Panels, Battery-Powered IoT Sensor Nodes, Home Appliance Control, USB-to-UART Bridge Devices, Sensor Signal Conditioning, Low-Cost Data Acquisition Systems.
Industrial Control Panels
The PIC18LF2221-I/SP is well suited for industrial control panels requiring multi-channel analog sensing and reliable digital I/O. Its 10-bit ADC with up to 13 channels reads temperature, pressure, and current sensors directly through on-chip signal conditioning, while 25 I/O pins drive relays, contactors, and indicator LEDs. The industrial temperature grade of -40C to +85C ensures operation across factory-floor environments, and the 2.0V to 5.5V supply accepts 24V-to-5V industrial power rails via inexpensive buck regulators. The 4 KB Flash accommodates typical panel-control state machines (typically 1500-2000 lines of C), while the 256-byte EEPROM stores calibration constants and configuration parameters across power cycles. The EUSART interfaces directly to RS-485 transceivers for Modbus RTU communication with PLCs.
Recommended
Battery-Powered IoT Sensor Nodes
The PIC18LF2221-I/SP's nanoWatt Technology and 2.0V minimum supply make it ideal for battery-powered IoT sensor nodes that must operate for years from a single CR2032 or AA cell. Sleep currents in the nanoWatt mode drop to single-digit microamps, while the wide 2.0V-5.5V range permits direct connection to lithium and alkaline chemistries without boost converters. The 512-byte SRAM handles short sensor data buffers before UART or RF transmission, and the 10-bit ADC reads battery voltage and environmental sensors with sufficient precision for threshold detection. The 28-SPDIP package simplifies breadboard prototyping for sensor-node reference designs, while the same die is available in QFN-28 (/ML) for space-constrained production modules.
Recommended
Home Appliance Control
Home appliances including washing machines, microwave ovens, dishwashers, and HVAC thermostats benefit from the PIC18LF2221-I/SP's mix of 4 KB Flash, 25 I/O pins, and PWM capability. The Enhanced CCP module generates PWM signals for motor control of low-power DC motors and TRIAC-based AC dimming, while the 10-bit ADC reads thermistor inputs for over-temperature shutdown and user-setpoint control. The 256-byte EEPROM retains the last operating mode and user preferences through power loss, and the SPI/I2C MSSP interfaces to LED driver chips and segment displays. Industrial temperature rating supports the thermal environment inside appliance chassis, while the through-hole SPDIP package accommodates hand-repairable designs common in domestic appliance manufacturing.
Recommended
USB-to-UART Bridge Devices
The PIC18LF2221-I/SP implements USB-to-UART bridges when paired with a USB-capable companion or programmed via bootloader, exploiting its hardware EUSART for the UART side and MSSP for SPI communication with the USB controller IC. The 40 MHz CPU throughput handles typical serial protocols at up to 921600 baud without dropped characters, and the 512-byte SRAM serves as a double-buffered UART FIFO. The 2.0V-5.5V supply directly interfaces to 3.3V USB regulators without level shifters, and the 256-byte EEPROM stores VID/PID/serial number descriptors for USB enumeration. Industrial temperature range supports deployment in industrial gateways and outdoor serial-line extenders.
Recommended
Sensor Signal Conditioning
Signal-conditioning front-ends for bridge sensors, RTDs, and thermocouples leverage the PIC18LF2221-I/SP's 10-bit ADC combined with its analog-friendly supply range. The 13 ADC channels multiplex multiple sensor inputs through the same MCU, eliminating the need for external analog multiplexers. The MSSP module connects to external 16-bit or 24-bit ADCs over SPI when higher resolution is needed, using the PIC as a digital signal processor and host interface. The 256-byte EEPROM stores calibration coefficients unique to each transducer, and the EUSART outputs conditioned readings to upstream data loggers or displays. The 28-SPDIP package simplifies bench-top calibration test fixtures.
Recommended
Low-Cost Data Acquisition Systems
Multi-channel data loggers used in environmental monitoring, energy metering, and laboratory instrumentation leverage the PIC18LF2221-I/SP's 10-bit ADC sampling across 13 channels under firmware control. The 40 MHz throughput captures each channel at 100 kHz aggregate rates while leaving CPU headroom for filtering and statistics. The 256-byte EEPROM records measurement headers and time stamps, while the 4 KB Flash accommodates averaging, peak-hold, and min/max algorithms. The EUSART streams formatted records to a host PC or to an external SD-card logger via SPI-controlled MMC interface. The -40C to +85C industrial grade ensures deployment in unattended outdoor enclosures and process-plant environments.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF2221-I/SP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F2221-I/SP | PIC18LF2220-I/SP | PIC18F2320-I/SP | ATmega8-16PU |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology (Atmel) |
| Package | 28-SPDIP | 28-SPDIP (same) | 28-SPDIP (same) | 28-SPDIP (same) | 28-PDIP (same footprint) |
| Core | PIC18 8-bit RISC | PIC18 8-bit RISC | PIC18 8-bit RISC | PIC18 8-bit RISC | AVR 8-bit RISC |
| Max CPU Speed | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 16 MHz (16 MIPS AVR) |
| Program Flash | 4 KB | 4 KB | 2 KB (-50%) | 8 KB (+100%) | 8 KB (+100%) |
| SRAM | 512 bytes | 512 bytes | 256 bytes (-50%) | 512 bytes | 1 KB (+100%) |
| EEPROM | 256 bytes | 256 bytes | 256 bytes | 256 bytes | 512 bytes (+100%) |
| Operating Voltage | 2.0V - 5.5V | 4.2V - 5.5V (5V only) | 2.0V - 5.5V | 4.2V - 5.5V (5V only) | 4.5V - 5.5V (5V only) |
| ADC Channels | 13 channels (10-bit) | 13 channels | None | 13 channels | 8 channels (10-bit) |
Key Differentiators
- Wide 2.0V-5.5V supply range with nanoWatt low-power sleep (vs PIC18F2221-I/SP)
- Larger 4 KB Flash with 10-bit ADC integrated (vs PIC18LF2220-I/SP)
- Industry-standard PIC18 toolchain (MPLAB X) with stable mature code base (vs ATmega8-16PU)
- Through-hole SPDIP package for breadboard-friendly prototyping (vs PIC18LF2221-I/ML (QFN-28))
Design Notes
The PIC18LF2221-I/SP nanoWatt Technology requires careful configuration of OSCCON, WDTCON, and the T0CON/T1CON registers to achieve low sleep currents. Estimated: with all peripherals off and CPU in Sleep mode at 3V VDD, the data sheet specifies typical 100 nA draw on the LF variant. Critical: configure all unused I/O pins as outputs driving low (or as inputs with weak pull-ups enabled) to prevent floating inputs from inducing parasitic current paths of several hundred microamps.
For 28-SPDIP through-hole layout, allocate 0.1-inch (2.54 mm) row pitch and standard 0.6 mm drill pads for through-hole pins. Place a 100 nF decoupling capacitor within 5 mm of the VDD pin (pin 11), and an additional bulk 1-10 uF tantalum or ceramic capacitor at the board-level VDD rail. The ICSP programming pins RB6/PGC (pin 18) and RB7/PGD (pin 19) should be brought out to a 6-pin header with /MCLR, VDD, VSS for in-circuit serial programming without removing the chip from the board.
Critical mistake to avoid: connecting the ADC reference pin VREF+ to a noisy 5V rail. According to the Microchip datasheet, the 10-bit ADC accuracy is specified with a stable reference. If used, drive VREF+ from a low-impedance precision reference such as MCP1525 or REF3030 instead of VDD. Also: PIC18F2221 and PIC18LF2221 share the same datasheet - ensure you read the LF sub-section for 2.0V minimum operation specs rather than the F-only section listing 4.2V minimum.
The 28-SPDIP package has wide lead spacing that keeps junction-to-ambient thermal resistance below 80 C/W under natural convection. Estimated: at full 40 MHz CPU throughput the LF part draws ~13 mA at 5V, dissipating ~65 mW and resulting in junction temperature rise of ~5 C above ambient in still air, well within industrial-grade limits. No thermal management is required for typical applications below 30 MHz operation in open-frame enclosures.
Compliance Information
RoHS compliant per Microchip product page and DigiKey listings. Industrial temperature grade -40C to +85C. Not AEC-Q100 qualified - this is a general-purpose MCU and would require a different variant for automotive applications.
