PIC18LF4221-I/PT - 8-Bit 40MHz 4KB Flash MCU | Microchip TQFP-44
MPN: PIC18LF4221-I/PT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.92 | $4.92 |
| 10 | $4.43 | $44.30 |
| 100 | $3.94 | $394.00 |
| 500 | $3.55 | $1,775.00 |
| 1,000 | $3.16 | $3,160.00 |
PIC18LF4221-I/PT Overview
An 8-bit microcontroller is a single-chip computer built around an 8-bit data path; it sits in a hierarchy that runs MCU -> 8-bit MCU -> embedded controller -> semiconductor. PIC18F devices add a 16-bit instruction word to an 8-bit data path, enabling linear addressing and higher code density than the legacy PIC16 family. Compared with 32-bit Cortex-M parts, 8-bit MCUs trade raw throughput for cost, deterministic interrupt latency, and decades of compiler/ecosystem support.
Key features include 40 MHz operation (10 MIPS), 4 KB Flash with 2K x 16 organization, 512 bytes of RAM, 34 digital I/O pins, 10-bit ADC with multiple channels, two analog comparators, two 8-bit and three 16-bit timers, and the nanoWatt Technology power management set for low-power sleep modes. The wide 2.0 V to 5.5 V supply range allows the part to run directly from a single Li-ion cell or from a regulated 3.3 V or 5 V rail without level shifting.
The device uses the proven PIC18 RISC architecture with a 16-bit instruction word and an 8-bit data bus, supported by the MPLAB XC8 toolchain and a complete family header-library ecosystem. Internal oscillator options, an integrated programmable brown-out reset, and a hardware watchdog provide design robustness without external components. The device operates across the industrial -40C to +85C temperature range with at least 100K erase/write cycles on Flash.
Typical applications include industrial control subsystems, consumer white-goods user interfaces, sensor signal conditioning nodes, low-power remote controls, USB-less human-interface peripherals, and battery-powered data loggers. The wide voltage and small footprint make the part a drop-in replacement choice when migrating from older PIC16 designs that need more code space than the previous generation could host.
When designing with the PIC18LF4221-I/PT, place a 100 nF decoupling capacitor as close as possible to the VDD pin and keep the MCLR pull-up trace short. Verify oscillator start-up margin at the lowest expected VDD if you rely on the internal HFINTOSC, since low-voltage start-up behavior depends on both temperature and the configured clock mode.
This page synthesizes distributor stock and pricing, a verified drop-in list, and design notes not found in the manufacturer datasheet to give engineers a single decision-ready reference for the PIC18LF4221-I/PT.
Drop-in alternatives for PIC18LF4221-I/PT — 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 PIC18LF4221-I/PT (same form factor and footprint) — differing in Timers, Package, ADC, Core Architecture, Program Memory (Flash).
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18LF4220-I/ML
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$4.61 / Unit
View Datasheet →PIC18LF4321-I/ML
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$4.43 / Unit
View Datasheet →PIC18F4520-I/PT
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4420-I/PT
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18LF4221-I/ML
✅ Drop-In✓ In Stock
$2.85 / Unit
View Datasheet →PIC18F46K20-I/PT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.78 / Unit
View Datasheet →PIC18LF4221-I/PT Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18F RISC, 8-bit data path, 16-bit instruction word |
| Program Memory (Flash) | 4 KB (2K x 16) |
| RAM | 512 bytes |
| Maximum CPU Clock | 40 MHz |
| MIPS (peak) | 10 MIPS |
| Supply Voltage (VDD) | 2.0 V to 5.5 V |
| Digital I/O Pins | 34 |
| ADC | 10-bit, enhanced |
| Comparators | 2 analog comparators |
| Timers | 2 x 8-bit, 3 x 16-bit |
| Communication Interfaces | UART, SPI, I2C (MSSP + AUSART) |
| Package | 44-pin TQFP (PT), 10x10 mm |
| Operating Temperature | -40C to +85C (Industrial) |
| Mounting Type | Surface Mount |
| MSL Level | 3 (per JEDEC J-STD-020) |
| Lead-Free / RoHS | Yes / Compliant |
| Brown-Out Reset | Yes, programmable |
| Watchdog Timer | Yes, hardware WDT |
| nanoWatt Power Management | Yes (Sleep, Idle, low-power modes) |
PIC18LF4221-I/PT Pin Configuration
| Pin 1 | MCLR/RE3 — Master Clear (reset) input / PORTE bit 3 |
| Pin 2 | RA0/AN0 — PORTA bit 0 / ADC channel 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / ADC channel 1 |
| Pin 4 | RA2/AN2/VREF- — PORTA bit 2 / ADC channel 2 / ADC VREF- |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / ADC channel 3 / ADC VREF+ |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4 — PORTA bit 5 / ADC channel 4 |
| Pin 8 | OSC1/CLKI — Crystal oscillator input / external clock |
| Pin 9 | OSC2/CLKO — Crystal oscillator output |
| Pin 10 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator |
| Pin 11 | RC1/T1OSI — PORTC bit 1 / Timer1 oscillator input |
| Pin 12 | RC2/CCP1 — PORTC bit 2 / CCP1 PWM/capture |
| Pin 13 | RC3/SCL/SCK — PORTC bit 3 / I2C SCL / SPI SCK |
| Pin 14 | RC4/SDA/SDI — PORTC bit 4 / I2C SDA / SPI SDI |
| Pin 15 | RC5/SDO — PORTC bit 5 / SPI SDO |
| Pin 16 | RC6/TX/CK — PORTC bit 6 / AUSART TX / clock |
| Pin 17 | RC7/RX/DT — PORTC bit 7 / AUSART RX / data |
| Pin 18 | VSS — Ground |
| Pin 19 | VDD — Positive supply (2.0-5.5 V) |
| Pin 20 | RB0/INT0 — PORTB bit 0 / External interrupt 0 |
| Pin 21 | RB1/INT1 — PORTB bit 1 / External interrupt 1 |
| Pin 22 | RB2/INT2 — PORTB bit 2 / External interrupt 2 |
| Pin 23 | RB3/CCP2 — PORTB bit 3 / CCP2 PWM/capture |
| Pin 24 | RB4 — PORTB bit 4 (interrupt-on-change) |
| Pin 25 | RB5 — PORTB bit 5 (interrupt-on-change) |
| Pin 26 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 27 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 28 | VSS — Ground (second VSS) |
| Pin 29 | VDD — Positive supply (second VDD) |
| Pin 30 | RD0 — PORTD bit 0 |
| Pin 31 | RD1 — PORTD bit 1 |
| Pin 32 | RD2 — PORTD bit 2 |
| Pin 33 | RD3 — PORTD bit 3 |
| Pin 34 | RD4 — PORTD bit 4 |
| Pin 35 | RD5 — PORTD bit 5 |
| Pin 36 | RD6 — PORTD bit 6 |
| Pin 37 | RD7 — PORTD bit 7 |
| Pin 38 | RE0/RD — PORTE bit 0 / parallel-port read strobe |
| Pin 39 | RE1/WR — PORTE bit 1 / parallel-port write strobe |
| Pin 40 | RE2/CS — PORTE bit 2 / parallel-port chip-select |
| Pin 41 | VSS — Ground (third VSS) |
| Pin 42 | VDD — Positive supply (third VDD) |
| Pin 43 | AVSS — Analog ground |
| Pin 44 | AVDD — Analog positive supply |
Typical Applications
PIC18LF4221-I/PT is suitable for 7 applications: Industrial Control Subsystem, Battery-Powered Sensor Node, Consumer Appliance User Interface, Remote Control and HMI Device, Data Acquisition Front-End, Automotive Body and Accessory Module, Educational and Prototyping Platform.
Industrial Control Subsystem
The PIC18LF4221-I/PT fits industrial control subsystems because its 8-bit PIC18 core delivers deterministic interrupt response and the 2.0-5.5 V wide supply accepts 24 V-bus rails regulated to 5 V or 3.3 V locally without an additional level shifter. The device's 34 I/O lines let it drive relays, optocouplers, and discrete sensors, while the 10-bit ADC reads back analog process variables (temperature, pressure, current) on a single chip. Programmable brown-out reset and the hardware watchdog survive brown-outs on long cable runs typical of factory floors. nanoWatt Sleep mode lets the MCU idle at microamp-level current between sensor scans, cutting dissipated heat in sealed cabinets.
Recommended
Battery-Powered Sensor Node
The 'LF' wide-voltage input allows the PIC18LF4221-I/PT to run directly from a single Li-ion cell (3.0-4.2 V) or two alkaline cells, eliminating the need for a boost/buck regulator that would otherwise drain the battery. nanoWatt Sleep, Idle, and low-power timer modes let the CPU wake, sample the 10-bit ADC, transmit over the AUSART, and return to sleep at microamp-level quiescent current. The 4 KB Flash is enough to hold a sensor-conditioning stack plus a small RTOS or scheduler, while 512 bytes RAM supports calibration tables and small packet buffers. Estimated: at 1 sample/min with AUSART 9600 baud, average current draw can stay below 50 uA on a 2000 mAh cell.
Recommended
Consumer Appliance User Interface
In white-goods and kitchen appliances, the PIC18LF4221-I/PT drives 7-segment or LCD character displays, scans keypads, and switches triacs/relays via its 34 I/O lines. The wide 2.0-5.5 V supply lets the same firmware image work on 3.3 V or 5 V board variants, simplifying SKU management for global product lines. Hardware PWM channels (CCP/ECCP) drive motor speeds, dimming waveforms, and buzzer tones without software overhead. The 10 MIPS peak at 40 MHz keeps display refresh latency and keypad debounce loops tightly bounded. nanoWatt Idle mode is used between user interactions to meet energy-star standby targets under 1 W.
Recommended
Remote Control and HMI Device
The PIC18LF4221-I/PT serves well in remote-control and human-machine-interface handsets because of its small footprint, 4 KB Flash, and integrated peripherals (UART, SPI, I2C). The AUSART can drive half-duplex RF links or IR transceivers with low software overhead, while the MSSP peripheral handles display controllers over SPI/I2C. The 2.0-5.5 V supply accepts two AA cells directly, simplifying battery management. nanoWatt Sleep mode keeps standby current near zero, extending remote-control battery life to years. Estimated: on two AA alkaline cells, a remote controlling a TV-style IR link can run 5+ years at typical click rates.
Recommended
Data Acquisition Front-End
The 10-bit enhanced ADC on the PIC18LF4221-I/PT, paired with 34 I/O, is sufficient for multi-channel data-acquisition front-ends on small PLCs and instrumentation. The ADC supports up to 8 channels and can run in sleep mode for low-noise conversions, leaving the CPU free for protocol handling. The MSSP peripheral streams data to external ADCs or to a host controller over SPI. Internal timer-capture modules decode frequency or pulse-width inputs from flow meters and tachometers. The industrial -40C to +85C rating keeps the part specified in outdoor and factory installations without thermal derating.
Recommended
Automotive Body and Accessory Module
While the PIC18LF4221-I/PT is not AEC-Q100 qualified, it is widely used inside non-safety automotive body and accessory modules such as interior lighting controllers, mirror-adjustment boards, and seat-position accessory modules. The 2.0-5.5 V supply tolerates cranking transients downstream of the battery, and the hardware watchdog plus brown-out reset ensure recovery from accessory-bus brown-outs. PWM channels drive LED strings and small DC motors directly. nanoWatt Sleep mode holds parasitic battery drain under 100 uA when the vehicle is parked. For AEC-Q100 safety-critical modules, choose the PIC18LF-family Q-graded siblings instead.
Recommended
Educational and Prototyping Platform
The PIC18LF4221-I/PT is popular in university embedded-systems labs because it offers a full PIC18 RISC core in an easy-to-hand TQFP-44 footprint. The MPLAB XC8 toolchain is free, the MPLAB X IDE runs on macOS, Linux, and Windows, and PICkit programmers start under $50. The 4 KB Flash is enough for textbook projects (PID loops, FSM controllers, UART bridges) while remaining small enough that students can read the entire firmware in one sitting. The wide voltage tolerance exercises students on real-world power-tree design choices. Many development boards and course kits re-use this part across multiple semesters.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF4221-I/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18LF4220-I/ML | PIC18F4520-I/PT | PIC18F46K20-I/PT |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-pin TQFP (PT), 10x10 mm | 44-pin QFN (ML) | 44-pin TQFP (PT) - same | 44-pin TQFP (PT) - same |
| Program Memory | 4 KB Flash (2K x 16) | 4 KB Flash | 32 KB Flash | 64 KB Flash |
| RAM | 512 bytes | 512 bytes | 1.5 KB | 3.6 KB |
| Maximum Clock | 40 MHz (10 MIPS) | 40 MHz | 40 MHz | 64 MHz |
| Supply Voltage | 2.0 V to 5.5 V (LF) | 2.0 V to 5.5 V (LF) | 4.2 V to 5.5 V (F) | 1.8 V to 3.6 V (K-series) |
| Digital I/O | 34 | 34 | 36 | 36 |
| ADC | 10-bit enhanced | 10-bit enhanced | 10-bit enhanced | 10-bit enhanced |
Key Differentiators
- Wide-voltage LF variant enables single-cell Li-ion and 3.3 V designs (vs PIC18F4520-I/PT)
- Smaller Flash footprint for cost-sensitive 4 KB firmware designs (vs PIC18F46K20-I/PT)
- TQFP-44 footprint with 34 I/O at low cost (vs PIC18LF4221-I/ML (QFN-44))
Design Notes
Place a 100 nF decoupling capacitor on each VDD pin as close to the package as possible, plus a bulk capacitor (typically 1 uF to 10 uF) at the board supply entry. For wide 2.0-5.5 V designs, verify brown-out reset (BOR) thresholds in the configuration words; an unstable BOR trip causes intermittent resets on slow-rising supplies. For battery-powered nodes, switch the CPU to the internal LFINTOSC during Sleep to hold current under 1 uA.
Keep the MCLR pull-up trace short (under 2 cm if possible) to prevent false resets from EMI bursts. Route the crystal traces (OSC1/OSC2) over a continuous ground pour and avoid crossing them with digital switching lines. Place the ICSP pins (RB6/RB7) on a 0.1 inch header footprint or test-pad cluster to keep programmer access easy without ribbon cables.
Watch for the difference between PIC18F (4.2-5.5 V) and PIC18LF (2.0-5.5 V) variants when substituting, since swapping an F part into an LF socket at 3.3 V will result in a non-functional board. Always re-check the configuration words for oscillator mode and watchdog enable before programming production firmware; the default ICSP configuration is rarely what you want for a deployed product.
When using the ADC, the AVDD/AVSS pins must be powered even if the ADC is unused, or VDD current may not meet datasheet limits. For best ADC accuracy at 10 bits, place the analog inputs on quiet port pins (avoid routing near PWM outputs) and add a small RC filter at each analog input when sourcing impedances exceed datasheet recommended values.
Compliance Information
RoHS / REACH lead-free per Microchip product page; not AEC-Q100 qualified - choose AEC-Q100 cousin for automotive. MSL Level 3 per JEDEC J-STD-020.