PIC18F4221-E/ML - 8-bit MCU, 4KB Flash, 40MHz, 44-QFN | Microchip
MPN: PIC18F4221-E/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.62 | $4.62 |
| 10 | $4.15 | $41.50 |
| 100 | $3.65 | $365.00 |
| 500 | $3.18 | $1,590.00 |
| 1,000 | $2.84 | $2,840.00 |
PIC18F4221-E/ML Overview
Background — What is an 8-bit PIC microcontroller? A microcontroller (MCU) is a single-chip computer that integrates a CPU, non-volatile program memory, working RAM, and peripherals such as ADC, timers, and communication blocks. The PIC18 family sits in the mid-range tier of Microchip's PIC portfolio, between the baseline PIC10/12/16 families and the high-performance PIC24/dsPIC families. PIC18 cores use a Harvard-style RISC design with 16-bit instructions and an 8-bit data path, balancing code density, deterministic timing, and C-compiler friendliness. MCUs like the PIC18F4221 typically serve as the supervisory brain in embedded systems, offloading housekeeping tasks from a host processor or running standalone in cost-sensitive designs.
Key features that distinguish this device include the nanoWatt power-management suite (which provides multiple idle and sleep modes with current as low as nA typical), self-programmability that enables in-field firmware updates without external programmers, an ICD (In-Circuit Debugger) interface, and a wide peripheral mix that targets both sensor-interface and human-interface applications. The 256-byte EEPROM block adds wear-leveled non-volatile storage for parameters that must survive power cycles. Programmable pull-ups, interrupt-on-change, and ultra-low-power wake-up sources simplify matrix-key and remote-control designs.
Architecturally, the PIC18F4221 uses an 8-bit data bus with a 16-bit instruction word and a hardware multiplier (8x8 in one cycle). The Flash memory supports table reads/writes and run-time self-programming via ICSP, and the device includes a 31-level hardware stack. The 10-bit ADC supports 13 input channels with acquisition time programmable via ADCON registers. The MSSP peripheral supports both SPI master/slave and I2C master/slave modes with 7-bit or 10-bit addressing. The EUSART handles RS-232/RS-485 asynchronous communications and synchronous master/slave protocols.
Typical applications include industrial control modules, sensor signal conditioning, low-cost motor and lighting controllers, USB-to-UART bridges (when paired with a USB transceiver IC), home appliances with user interfaces, and battery-powered instrumentation that benefits from the nanoWatt sleep modes. The 44-pin QFN package provides a compact footprint for space-constrained designs while still exposing most of the PIC18 family's peripherals.
Design consideration: the 44-pin QFN's exposed thermal pad must be soldered to a ground pad on the PCB to meet the package's thermal and electrical performance; omitting the pad connection can degrade ADC accuracy and ESD robustness. When migrating firmware between PIC18F4221 variants (e.g., -I/ML industrial vs. -E/ML extended grade), verify that code-protection bits and oscillator configuration match the target application.
This page synthesizes distributor pricing, same-package drop-in alternatives, and practical design notes not found in the manufacturer datasheet, helping engineers shorten sourcing and qualification cycles for the PIC18F4221-E/ML.
Drop-in alternatives for PIC18F4221-E/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 PIC18F4221-E/ML (same form factor and footprint) — differing in Package, Operating Temperature, Timers, ADC, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F4220-I/ML
✅ Drop-In✓ In Stock
$3.97 / Unit
View Datasheet →PIC18F4220T-I/ML
✅ Drop-In✓ In Stock
$3.64 / Unit
View Datasheet →PIC18F4220-I/P
✅ Drop-In✓ In Stock
$4.78 / Unit
View Datasheet →PIC18F4220-E/P
✅ Drop-In✓ In Stock
$4.65 / Unit
View Datasheet →PIC18F4553-I/ML
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →PIC18F46J50-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F47J53-I/ML
✅ Drop-In✓ In Stock
$5.2 / Unit
View Datasheet →PIC18F4221-E/ML Maximum Ratings & Electrical Characteristics
| Core | PIC18 8-bit RISC |
| Program Memory | 4 KB Flash |
| SRAM | 512 bytes |
| EEPROM | 256 bytes |
| Maximum CPU Frequency | 40 MHz (10 MIPS) |
| Supply Voltage | 4.2 V to 5.5 V |
| I/O Pins | 36 |
| ADC | 10-bit, 13 channels |
| Analog Comparators | 2 |
| CCP Modules | 2 |
| Serial Interfaces | MSSP (SPI/I2C), EUSART (RS-232/RS-485) |
| Timers | 4 (TMR0/TMR1/TMR2/TMR3) |
| Package | 44-pin VQFN (ML) with exposed pad |
| Operating Temperature | -40C to +125C (Extended, "E") |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Self-Programming / ICSP | Yes |
| nanoWatt Power Management | Yes |
PIC18F4221-E/ML Pin Configuration
| Pin 1 | RA2/AN2/VREF- — Digital I/O / analog input / ADC voltage reference low |
| Pin 2 | RA3/AN3/VREF+ — Digital I/O / analog input / ADC voltage reference high |
| Pin 3 | RA4/T0CKI — Digital I/O / Timer0 clock input |
| Pin 4 | RA5/AN4/SS — Digital I/O / analog input / SPI slave select |
| Pin 5 | RA6/OSC2/CLKO — Digital I/O / oscillator output / clock output |
| Pin 6 | RA7/OSC1/CLKI — Digital I/O / oscillator input / clock input |
| Pin 7 | VDD — Positive supply voltage |
| Pin 8 | VSS — Ground reference |
| Pin 9 | RB0/INT0/FLT0 — Digital I/O / external interrupt 0 / PWM fault input |
| Pin 10 | RB1/INT1 — Digital I/O / external interrupt 1 |
| Pin 11 | RB2/INT2 — Digital I/O / external interrupt 2 |
| Pin 12 | RB3/INT3/CCP2 — Digital I/O / external interrupt 3 / CCP2 output |
| Pin 13 | RB4/KBI0 — Digital I/O / interrupt-on-change |
| Pin 14 | RB5/KBI1 — Digital I/O / interrupt-on-change |
| Pin 15 | RB6/KBI2/PGC — Digital I/O / interrupt-on-change / ICSP clock |
| Pin 16 | RB7/KBI3/PGD — Digital I/O / interrupt-on-change / ICSP data |
| Pin 17 | VDD — Positive supply voltage |
| Pin 18 | VSS — Ground reference |
| Pin 19 | RC0/T1OSO/T1CKI — Digital I/O / Timer1 oscillator output / Timer1 clock |
| Pin 20 | RC1/T1OSI/CCP2 — Digital I/O / Timer1 oscillator input / CCP2 |
| Pin 21 | RC2/CCP1 — Digital I/O / CCP1 output |
| Pin 22 | RC3/SCK/SCL — Digital I/O / SPI clock / I2C clock |
| Pin 23 | RC4/SDI/SDA — Digital I/O / SPI data in / I2C data |
| Pin 24 | RC5/SDO — Digital I/O / SPI data out |
| Pin 25 | RC6/TX/CK — Digital I/O / EUSART transmit / EUSART clock |
| Pin 26 | RC7/RX/DT — Digital I/O / EUSART receive / EUSART data |
| Pin 27 | VDD — Positive supply voltage |
| Pin 28 | VSS — Ground reference |
| Pin 29 | RD0 — Digital I/O port D bit 0 |
| Pin 30 | RD1 — Digital I/O port D bit 1 |
| Pin 31 | RD2 — Digital I/O port D bit 2 |
| Pin 32 | RD3 — Digital I/O port D bit 3 |
| Pin 33 | RD4 — Digital I/O port D bit 4 |
| Pin 34 | RD5 — Digital I/O port D bit 5 |
| Pin 35 | RD6 — Digital I/O port D bit 6 |
| Pin 36 | RD7 — Digital I/O port D bit 7 |
| Pin 37 | VSS — Ground reference |
| Pin 38 | VDD — Positive supply voltage |
| Pin 39 | RE0/RD/AN5 — Digital I/O / read control / analog input |
| Pin 40 | RE1/WR/AN6 — Digital I/O / write control / analog input |
| Pin 41 | RE2/CS/AN7 — Digital I/O / chip select / analog input |
| Pin 42 | RE3/MCLR/VPP — Digital I/O / master clear / programming voltage |
| Pin 43 | RA0/AN0 — Digital I/O / analog input |
| Pin 44 | RA1/AN1 — Digital I/O / analog input |
Typical Applications
PIC18F4221-E/ML is suitable for 7 applications: Industrial Sensor Conditioning Module, Home Appliance User-Interface Controller, HVAC Fan and Blower Motor Controller, RS-232/RS-485 Sensor Network Node, Battery-Backed Data Logger, Automotive Interior Lighting Controller, Educational and Prototyping Platform.
Industrial Sensor Conditioning Module
The PIC18F4221-E/ML is well matched to industrial sensor-conditioning modules that digitize analog signals from thermocouples, RTDs, pressure transducers, or 4-20 mA loops. The 13-channel 10-bit ADC provides enough simultaneous-input headroom for multi-sensor front-ends while the 5V native supply matches typical industrial signal conditioning rails without level shifting. The extended -40C to +125C operating temperature grade allows deployment in unheated enclosures near motors or furnaces, and the nanoWatt sleep modes let battery-backed sensor nodes idle below 1 mA between measurements.
Recommended
Home Appliance User-Interface Controller
Washing machines, dishwashers, ovens, and induction cooktops benefit from the PIC18F4221-E/ML's generous mix of 36 I/O pins, 13 ADC channels, and 2 CCP modules for driving triac-based dimmers, buzzer PWM tones, and segmented LED or LCD displays. The Extended temperature rating sustains control loops near heating elements, and the 256-byte EEPROM stores user preferences and last-cycle state through power cycles. Its nanoWatt idle keeps standby power below typical energy-star targets for white goods.
Recommended
HVAC Fan and Blower Motor Controller
The PIC18F4221-E/ML drives single-phase BLDC or AC induction blower motors via its CCP modules configured as PWM outputs, with the 10-bit ADC sampling current-sense shunts or back-EMF dividers to implement closed-loop speed control. The 5V supply integrates directly with 24V-to-5V derived HVAC rails, and the -40C to +125C grade handles rooftop and attic-mounted equipment in summer peaks. The MSSP peripheral drives SPI/I2C sensors for temperature, humidity, and airflow feedback in a single MCU.
Recommended
RS-232/RS-485 Sensor Network Node
The PIC18F4221-E/ML's integrated EUSART supports RS-232, RS-485, and synchronous serial protocols, making it a strong fit for half-duplex multidrop sensor networks in industrial building-automation and process-control plants. Its 5V signaling directly drives MAX485-style transceivers without level shifters, and the 256-byte EEPROM stores node address and calibration constants. Extended temperature operation lets it survive outdoor or cabinet-mounted deployment; nanoWatt sleep modes allow battery-backed nodes to maintain watch-dog polling.
Recommended
Battery-Backed Data Logger
The PIC18F4221-E/ML powers low-power data loggers that sample sensors periodically and store records to either the on-chip 256-byte EEPROM or an external SPI/I2C EEPROM/FRAM. Its nanoWatt sleep current extends battery life in unattended environmental monitoring deployments, and the 10-bit ADC is sufficient for slow-changing phenomena such as temperature, humidity, and soil-moisture logging. The 36 I/O pins accept multiple sensor interfaces including 1-Wire, SPI, and I2C peripherals.
Recommended
Automotive Interior Lighting Controller
Although not AEC-Q100 qualified, the PIC18F4221-E/ML is commonly designed into non-safety automotive interior applications such as ambient LED lighting, RGB footwell illumination, and courtesy-light fade controllers, particularly in commercial vehicle and aftermarket segments. The CCP/PWM modules generate smooth LED fade curves, the EUSART handles LIN or CAN-via-transceiver command links, and the Extended -40C to +125C temperature range survives cabin and under-dash thermal stress. Two analog comparators support zero-cross detection for AC-driven lighting.
Recommended
Educational and Prototyping Platform
The PIC18F4221-E/ML is a popular teaching MCU on university curricula and DIY maker boards because of its manageable peripheral count, free MPLAB X IDE toolchain, and mature XC8 C compiler support. The 44-QFN package is supported by Microchip's Curiosity Development Platform and a wide ecosystem of third-party programmers/debuggers including PICkit 3, PICkit 4, and MPLAB SNAP. The Extended temperature grade lets students run classroom lab exercises outdoors or in vehicle-mounted projects.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F4221-E/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4220-I/ML | PIC18F4220T-I/ML | PIC18F4553-I/ML | PIC18F46J50-I/ML | PIC18F47J53-I/ML |
|---|---|---|---|---|---|---|
| Package | 44-QFN (ML) | 44-QFN (ML) - same | 44-QFN (ML) - same | 44-QFN (ML) - same | 44-QFN (ML) - same | 44-QFN (ML) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 4 KB | 4 KB | 4 KB | 24 KB | 64 KB | 128 KB |
| SRAM | 512 B | 512 B | 512 B | 2 KB | 3.8 KB | 3.8 KB |
| Max CPU Frequency | 40 MHz | 40 MHz | 40 MHz | 48 MHz | 48 MHz | 48 MHz |
| Supply Voltage | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 2.0 V to 3.6 V | 2.0 V to 3.6 V |
| Operating Temperature | -40C to +125C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
| USB Peripheral | No | No | No | Yes (USB 2.0 FS) | Yes (USB 2.0 FS OTG) | Yes (USB 2.0 FS OTG) |
| ADC Channels | 13 | 13 | 13 | 13 | 13 | 13 |
| I/O Pins | 36 | 36 | 36 | 34 | 34 | 34 |
Key Differentiators
- Extended -40C to +125C temperature grade in a 44-QFN package (vs PIC18F4220-I/ML)
- Minimal 4 KB Flash / 512 B SRAM footprint optimized for cost-sensitive industrial control (vs PIC18F47J53-I/ML)
- 13 ADC channels on 36 I/O pins with 2 CCP/PWM blocks (vs PIC18F46J50-I/ML)
Design Notes
The 44-pin QFN (ML) package has an exposed thermal pad that must be soldered to the PCB ground plane. Per the Microchip PIC18F4221 datasheet, leaving the pad unconnected can degrade ADC accuracy by several LSBs and reduce ESD survivability to below 1 kV HBM. Use an array of thermal vias (typically 9 to 16 vias on a 1.0 mm pitch) connecting the pad to a ground pour on internal PCB layers.
Place a 0.1 uF ceramic decoupling capacitor as close as possible to each VDD pin (pins 7, 17, 27, 38) and a bulk 10 uF tantalum or ceramic capacitor near the MCU. The PIC18F4221-E/ML draws up to 16 mA at 40 MHz with all peripherals active; under-sizing the bulk capacitor causes VDD rail droop during CCP PWM transitions and may trigger brown-out resets if BOR is enabled.
When migrating firmware between PIC18F4221 temperature grades (-E vs -I), verify the CONFIG3H register's voltage regulator configuration bit. The Extended -40C to +125C grade supports the same 4.2V-5.5V supply as the industrial variant, but using a 3.3V supply rail on either grade will violate VDD_min and cause undefined Flash programming behavior.
Keep traces to the OSC1/OSC2 (RA7/RA6) pins short and shield them from switching signals such as PWM CCP outputs to avoid coupling noise into the system clock. If using an external crystal, add 1 MOhm resistor in parallel with the crystal load capacitors (typically 15-33 pF) per Microchip oscillator design guidelines to ensure stable start-up across the extended -40C to +125C range.
Compliance Information
RoHS and REACH compliance per Microchip product page. Lead-free reflow profile JEDEC J-STD-020. Not AEC-Q100 qualified - the PIC18F4221-E/ML targets industrial/consumer markets; for AEC-Q100 automotive designs, consult Microchip's automotive-qualified PIC18 catalog.
