PIC18LF2221-I/ML - 8-Bit MCU, 4KB Flash, 40MHz, 28-QFN | Microchip
MPN: PIC18LF2221-I/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.31 | $2.31 |
| 10 | $2.07 | $20.70 |
| 100 | $1.78 | $178.00 |
| 500 | $1.55 | $775.00 |
| 1,000 | $1.4 | $1,400.00 |
PIC18LF2221-I/ML Overview
A PIC18 microcontroller belongs to the 8-bit RISC microcontroller family, where a Harvard-architecture CPU executes most instructions in a single cycle, giving the PIC18F2xxx series up to 10 MIPS at 40MHz. Within Microchip's product hierarchy, PIC18 sits above the PIC16 baseline family and below the PIC24/dsPIC 16-bit families, offering a balance of code density, peripheral integration, and toolchain maturity. The 'LF' sub-family specifically targets low-voltage applications between 2.0V and 3.6V, distinguishing it from the standard PIC18F2221 (2.0V to 5.5V) and the PIC18LF2221T (tape-and-reel variant).
Key features of the PIC18LF2221-I/ML include 4KB (2K x 16) Flash program memory, 256 bytes EEPROM data memory, 512 bytes SRAM, a 10-bit ADC with up to 13 input channels, two 8-bit and one 16-bit timers, an enhanced USART, MSSP I2C/SPI, and a nanoWatt technology power-management suite. The industrial temperature grade (-40C to +85C) and the QFN-28 (ML) package with exposed thermal pad support compact designs up to 6x6mm.
The architecture uses a RISC instruction set with 16-bit instructions and 8-bit data path, allowing single-cycle execution for most instructions except branches. The 40MHz oscillator is paired with a 4x phase-locked loop option, internal 31kHz and 8MHz RC oscillators for fail-safe and low-power operation, and the nanoWatt features provide multiple idle and sleep modes measured in microamperes.
Typical applications for the PIC18LF2221-I/ML include low-power sensor interfaces, USB bridge controllers when paired with PIC18LF2550/4550, small appliances, and industrial control nodes where 4KB of Flash and a QFN-28 footprint are sufficient. Designers usually choose the LF sub-family over the F sub-family when the system is permanently battery-powered between 2.5V and 3.3V, where the LF device draws lower quiescent current.
When designing with the PIC18LF2221-I/ML, ensure the supply stays within 2.0V to 3.6V, route the exposed pad to the ground plane for thermal dissipation, and reserve ICSP pins (RB6/RB7) for in-circuit programming. The MPLAB X IDE and XC8 compiler are the recommended toolchain for code development and debugging.
Drop-in alternatives for PIC18LF2221-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 PIC18LF2221-I/ML (same form factor and footprint) — differing in ADC, Package, Operating Temperature, Core Architecture, Maximum CPU Speed.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18LF2220-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF2550-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF2221T-I/ML
✅ Drop-In✓ In Stock
$1.84 / Unit
View Datasheet →PIC18LF14K22-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2221-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF2221-I/ML Maximum Ratings & Electrical Characteristics
| Core | PIC18 8-bit RISC |
| Program Memory | 4 KB (2K x 16) Flash |
| RAM | 512 bytes |
| EEPROM | 256 bytes |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Operating Voltage (LF) | 2.0 V to 3.6 V |
| ADC | 10-bit, up to 13 channels |
| Timers | 2x 8-bit, 1x 16-bit |
| Communication | EUSART, MSSP (I2C/SPI) |
| Package | QFN-28 (ML) 6x6 mm with exposed pad |
| Operating Temperature | -40C to +85C (Industrial) |
| I/O Pins | 25 (approximate) |
| Mounting Type | Surface Mount |
| MSL Level | 3 (168 hours) |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC18LF2221-I/ML Pin Configuration
| Pin 1 | RA2/AN2 — Digital I/O / Analog input channel 2 |
| Pin 2 | RA3/AN3 — Digital I/O / Analog input channel 3 |
| Pin 3 | RA4/T0CKI — Digital I/O / Timer0 clock input |
| Pin 4 | RA5/AN4 — Digital I/O / Analog input channel 4 |
| Pin 5 | VSS — Ground reference |
| Pin 6 | OSC1/RA7 — Crystal oscillator input / digital I/O |
| Pin 7 | OSC2/RA6 — Crystal oscillator output / digital I/O |
| Pin 8 | VSS (EP) — Exposed pad, must be soldered to ground |
| Pin 9 | RC0 — Digital I/O port C |
| Pin 10 | RC1 — Digital I/O port C |
| Pin 11 | RC2 — Digital I/O port C |
| Pin 12 | RC3 — Digital I/O port C |
| Pin 13 | RC4 — Digital I/O port C |
| Pin 14 | RC5 — Digital I/O port C |
| Pin 15 | RC6 — Digital I/O port C |
| Pin 16 | RC7 — Digital I/O port C |
| Pin 17 | RB0/INT0 — Digital I/O / External interrupt 0 |
| Pin 18 | RB1/INT1 — Digital I/O / External interrupt 1 |
| Pin 19 | RB2 — Digital I/O port B |
| Pin 20 | RB3 — Digital I/O port B |
| Pin 21 | RB4 — Digital I/O port B |
| Pin 22 | RB5 — Digital I/O port B |
| Pin 23 | RB6/PGC — Digital I/O / ICSP clock |
| Pin 24 | RB7/PGD — Digital I/O / ICSP data |
| Pin 25 | VDD — Positive supply voltage |
| Pin 26 | VDD — Positive supply voltage (second pin) |
| Pin 27 | RE3/MCLR — Reset input / programming voltage |
| Pin 28 | RA0/AN0 — Digital I/O / Analog input channel 0 |
Typical Applications
PIC18LF2221-I/ML is suitable for 6 applications: Low-Power Sensor Interface, USB Bridge / Communication Bridge, Industrial Control Nodes, Small Appliance Control, Wearable / Fitness Device Controller, Educational / Hobbyist Projects.
Low-Power Sensor Interface
The PIC18LF2221-I/ML's 2.0V to 3.6V LF voltage range and nanoWatt sleep currents below 1 microampere make it ideal for battery-powered sensor nodes. Its 10-bit ADC with up to 13 input channels can directly digitize analog signals from temperature, pressure, or light sensors without external analog front-ends. With 4KB Flash and 512B RAM, the device handles typical sensor-fusion firmware with room for calibration tables. Compared to the 5V PIC18F2221, the LF variant significantly reduces quiescent current for multi-year battery life designs.
Recommended
USB Bridge / Communication Bridge
When USB connectivity is later required, the PIC18LF2221-I/ML serves as a stepping stone to the pin-compatible PIC18LF2550-I/ML in the same QFN-28 footprint. The shared peripheral set, including EUSART and MSSP I2C/SPI, allows firmware migration with minimal code changes. For designs already running the 2221, the USB-equipped 2550 enables USB-to-UART or USB-to-SPI bridges without PCB rework. This makes the PIC18LF family attractive for cost-optimized product roadmaps that may add USB in a future revision.
Recommended
Industrial Control Nodes
The PIC18LF2221-I/ML's industrial temperature grade (-40C to +85C), robust PIC18 architecture, and 40MHz CPU speed suit it for industrial control nodes such as sensor hubs, motor-control peripherals, and small PLCs. Its nanoWatt technology allows the device to enter sleep mode between control cycles, reducing average power in remote installations. The QFN-28 footprint supports dense PCB layouts where 25 I/O pins must connect to multiple analog and digital channels, and the exposed pad ensures thermal stability at elevated ambient temperatures.
Recommended
Small Appliance Control
In small appliances such as coffee machines, fans, and kitchen timers, the PIC18LF2221-I/ML offers sufficient Flash (4KB) for control loops, button-debounce routines, and PWM dimming, while the LF voltage range supports direct battery or 3.3V regulator operation. The 10-bit ADC reads thermistor or potentiometer inputs for closed-loop control, and the EUSART enables communication with display modules or wireless companions. Compared to a 5V PIC, the LF variant is preferred when the appliance is battery-powered and energy budget is critical.
Recommended
Wearable / Fitness Device Controller
Wearables and fitness trackers benefit from the PIC18LF2221-I/ML's compact QFN-28 (6x6mm) footprint and low-voltage operation from 2.0V to 3.6V, which matches single-cell Li-ion or coin-cell batteries directly. The nanoWatt sleep currents below 1 microampere extend battery life to weeks or months for always-on wearables. The 10-bit ADC captures signals from optical heart-rate or motion sensors, while the EUSART links to a Bluetooth companion module such as the RN4871. The exposed pad on the QFN package enables reliable thermal performance in enclosed wearable enclosures.
Recommended
Educational / Hobbyist Projects
The PIC18LF2221-I/ML is well-suited for educational use and hobbyist projects because it is fully supported by Microchip's free MPLAB X IDE, the free XC8 compiler, and the low-cost PICkit programmers. The 4KB Flash budget fits typical learning projects such as LED blinking, PWM motor control, and I2C sensor interfacing. The QFN-28 footprint encourages students to learn reflow soldering and QFN handling, while the LF voltage range supports battery-powered robot kits. Compared to the older PIC16F family, the PIC18 architecture offers more RAM and peripherals at a similar cost.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF2221-I/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18LF2220-I/ML | PIC18LF2550-I/ML | PIC18LF2221T-I/ML | PIC18LF14K22-I/ML | PIC18F2221-I/ML |
|---|---|---|---|---|---|---|
| Package | QFN-28 (ML) 6x6 mm | QFN-28 (ML) - same | QFN-28 (ML) - same | QFN-28 (ML) - same | QFN-28 (ML) - same | QFN-28 (ML) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 4 KB | 4 KB | 4 KB | 4 KB | 16 KB | 4 KB |
| RAM | 512 B | 512 B | 1536 B | 512 B | 512 B | 512 B |
| Operating Voltage | 2.0 V to 3.6 V (LF) | 2.0 V to 3.6 V (LF) | 2.0 V to 3.6 V (LF) | 2.0 V to 3.6 V (LF) | 2.0 V to 3.6 V (LF) | 2.0 V to 5.5 V (F) |
| ADC | 10-bit, up to 13 channels | None | 10-bit, up to 13 channels | 10-bit, up to 13 channels | 10-bit, up to 11 channels | 10-bit, up to 13 channels |
| USB Peripheral | No | No | USB 2.0 Full-Speed | No | No | No |
| Maximum CPU Speed | 40 MHz (10 MIPS) | 40 MHz | 48 MHz | 40 MHz | 64 MHz | 40 MHz |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
Key Differentiators
- Lower operating voltage range than F variant (vs PIC18F2221-I/ML)
- Pin-compatible upgrade path to USB (vs PIC18LF2550-I/ML)
- Compact 6x6mm QFN footprint (vs PIC18F46K22-I/PT)
- 4KB Flash with 10-bit ADC on board (vs PIC18LF2220-I/ML)
Design Notes
The QFN-28 (ML) package has an exposed thermal pad on the bottom that must be soldered to the ground plane for both electrical grounding and thermal dissipation. Use a 1:1 land pattern with thermal vias (typically 4 to 9 vias in a 0.3mm grid) to connect the pad to inner ground layers. Failure to solder the exposed pad can cause erratic resets or thermal shutdown under load. Keep high-speed signals and noisy traces away from the exposed pad region to avoid coupling into the ground reference.
Place a 100nF decoupling capacitor as close as possible to each VDD pin (pins 25 and 26) and a bulk 10uF tantalum or ceramic capacitor on the main power rail. According to Microchip's PIC18 hardware design checklist, a ferrite bead in series with VDD can further suppress switching noise from digital peripherals. For LF designs running from a coin cell or Li-ion battery, ensure the bulk capacitor can supply peak current during ADC conversions and EUSART bursts.
Do not exceed 3.6V on VDD for PIC18LF2221-I/ML - the LF variant is not 5V tolerant like the PIC18F2221. Applying 5V to an LF pin can permanently damage the device. Also reserve RB6 (PGC) and RB7 (PGD) for ICSP programming; do not load these pins with heavy external circuitry that prevents in-circuit programming. According to the datasheet, the MCLR pin (RE3) requires a 10k pull-up to VDD for normal operation and a series resistor if in-circuit programming is used.
Route the crystal oscillator traces (OSC1/OSC2) as short as possible and keep them away from switching signals. Place the crystal load capacitors (typically 15pF to 33pF) close to the MCU pins. For designs that use the internal 31kHz or 8MHz oscillator, the OSC1/OSC2 pins can be repurposed as RA7/RA6 digital I/O. According to Microchip's oscillator design guide, avoid routing digital signals under the crystal to minimize stray capacitance.
Compliance Information
RoHS and lead-free compliance per Microchip product page. Not AEC-Q100 qualified - the standard /ML is industrial-grade (-40C to +85C). For automotive designs, refer to AEC-Q100 qualified PIC18 variants.
