PIC18F4221-I/P - 8-bit 40MHz 4KB Flash MCU | Microchip DIP-40
MPN: PIC18F4221-I/P ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.35 | $5.35 |
| 10 | $4.78 | $47.80 |
| 100 | $4.21 | $421.00 |
| 500 | $3.62 | $1,810.00 |
| 1,000 | $3.15 | $3,150.00 |
PIC18F4221-I/P Overview
An 8-bit microcontroller (MCU) is a single-chip computer that uses an 8-bit data path and Harvard or modified-Harvard architecture optimized for deterministic, low-latency control of sensors, switches, and actuators. PIC microcontrollers belong to the broader category of microcontrollers (MCU) -> 8-bit MCU -> RISC MCU -> embedded controller -> semiconductor IC. They compete with AVR, 8051, and STM8 families and are widely used in cost-sensitive, low-power industrial and consumer designs where ease of programming (C compiler-friendly) and long product lifecycles matter most.
The PIC18F4221-I/P features nanoWatt technology for power-managed sleep modes, an ICD (In-Circuit Debugger) interface, self-programmability for field firmware updates, and 256-byte data EEPROM for non-volatile parameter storage. Its enhanced flash memory supports read-while-write operation, and the C compiler-optimized instruction set (200 ns instruction cycle at 40 MHz) makes code generation straightforward for designers migrating from PIC16 or PIC17 platforms.
The architecture combines a RISC CPU core with peripheral modules including two CCP (Capture/Compare/PWM) channels, a USART with addressable asynchronous mode, and an enhanced addressable synchronous serial port. Internal oscillator options and the nanoWatt power management block (Idle, Sleep, and Run modes with on-the-fly clock switching) enable battery-friendly operation in remote sensor nodes, while the 13-channel 10-bit ADC supports direct interface to analog front-ends.
Typical applications include industrial control panels, sensor signal conditioning, low-end motor control (DC brushed and small steppers via CCP/PWM), home appliances, automotive body electronics (non-safety), HVAC thermostats, and consumer white goods. The wide 4.2-5.5V supply range and 40-pin PDIP package make the part especially popular in hobbyist, education, and legacy industrial platforms where through-hole soldering and breadboard prototyping remain standard.
When designing with this part, reserve the MCLR/VPP pin for in-circuit serial programming (ICSP) and ensure decoupling capacitance of 0.1 uF plus 10 uF bulk is placed within 5 mm of VDD. For low-power designs, use the nanoWatt sleep modes and configure the ADC clock prescaler to avoid continuous conversion wake-ups. The 40-pin PDIP package simplifies prototyping but limits board density - migrate to the 44-pin TQFP (PIC18F4421-I/PT) or 44-pin QFN variants when production volume requires SMD assembly.
This page synthesizes distributor pricing (DigiKey, Mouser, LCSC), pin-compatible drop-in alternatives from the same PIC18F family, and practical design notes not collected in any single manufacturer datasheet.
Drop-in alternatives for PIC18F4221-I/P — 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-I/P (same form factor and footprint) — differing in Package, Timers, ADC, Operating Temperature, RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F4321-I/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4220-I/P
✅ Drop-In✓ In Stock
$4.78 / Unit
View Datasheet →PIC18F45K22-I/P
✅ Drop-In✓ In Stock
$2.1 / Unit
View Datasheet →PIC18F4520-I/P
✅ Drop-In✓ In Stock
$5.35 / Unit
View Datasheet →PIC18F4221-I/P Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 (8-bit RISC) |
| Program Memory (Flash) | 4 KB (2K x 16) |
| Data SRAM | 512 bytes |
| Data EEPROM | 256 bytes |
| Maximum CPU Clock | 40 MHz |
| Instruction Throughput | 16 MIPS (200 ns instruction cycle) |
| Supply Voltage (VDD) | 4.2 V to 5.5 V |
| Digital I/O Pins | 36 |
| ADC | 10-bit, 13 channels |
| Analog Comparators | 2 |
| Timers | 1 x 8-bit, 3 x 16-bit |
| CCP/PWM Channels | 2 |
| Serial Interfaces | 1 x USART (enhanced), 1 x MSSP (SPI/I2C) |
| Package | 40-pin PDIP (DIP-40) |
| Operating Temperature | -40C to +85C (Industrial, -I suffix) |
| Power-Saving Modes | nanoWatt (Idle, Sleep, RC_RUN, RC_IDLE) |
| ICSP / ICD | Yes (In-Circuit Serial Programming + Debug) |
| RoHS Status | Compliant (lead-free finish) |
PIC18F4221-I/P Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (reset, active low) / programming voltage input |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input 1 |
| Pin 4 | RA2/AN2/VREF- — PORTA bit 2 / Analog input 2 / ADC negative reference |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input 3 / ADC positive reference |
| Pin 6 | RA4/T0CKI/C1OUT — PORTA bit 4 / Timer0 clock input / Comparator 1 output |
| Pin 7 | RA5/AN4/SS/HLVDIN/C2OUT — PORTA bit 5 / Analog input 4 / SSP slave select / HV detect / Comparator 2 output |
| Pin 8 | OSC1/CLKI/RA7 — Crystal oscillator input 1 / external clock in / PORTA bit 7 |
| Pin 9 | OSC2/CLKO/RA6 — Crystal oscillator output 2 / clock out / PORTA bit 6 |
| Pin 10 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 11 | VDD — Positive supply voltage |
| Pin 12 | VSS — Ground reference |
| Pin 13 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 PWM output |
| Pin 14 | RC2/CCP1 — PORTC bit 2 / CCP1 PWM output |
| Pin 15 | RC3/SCK/SCL — PORTC bit 3 / SSP SPI clock / I2C clock |
| Pin 16 | RC4/SDI/SDA — PORTC bit 4 / SSP SPI data in / I2C data |
| Pin 17 | RC5/SDO — PORTC bit 5 / SSP SPI data out |
| Pin 18 | RC6/TX/CK — PORTC bit 6 / USART asynchronous transmit / synchronous clock |
| Pin 19 | RC7/RX/DT — PORTC bit 7 / USART asynchronous receive / synchronous data |
| Pin 20 | RB0/INT0/AN12 — PORTB bit 0 / External interrupt 0 / Analog input 12 |
| Pin 21 | RB1/INT1/AN10 — PORTB bit 1 / External interrupt 1 / Analog input 10 |
| Pin 22 | RB2/INT2/AN8 — PORTB bit 2 / External interrupt 2 / Analog input 8 |
| Pin 23 | RB3/AN9/CCP2 — PORTB bit 3 / Analog input 9 / CCP2 PWM output (alt) |
| Pin 24 | RB4/KBI0/AN11 — PORTB bit 4 / Interrupt-on-change bit 0 / Analog input 11 |
| Pin 25 | RB5/KBI1/PGM — PORTB bit 5 / Interrupt-on-change bit 1 / LVP programming |
| Pin 26 | RB6/KBI2/PGC — PORTB bit 6 / Interrupt-on-change bit 2 / ICSP clock |
| Pin 27 | RB7/KBI3/PGD — PORTB bit 7 / Interrupt-on-change bit 3 / ICSP data |
| Pin 28 | RE0/RD/AN5 — PORTE bit 0 / Read control / Analog input 5 |
| Pin 29 | RE1/WR/AN6 — PORTE bit 1 / Write control / Analog input 6 |
| Pin 30 | RE2/CS/AN7 — PORTE bit 2 / Chip select / Analog input 7 |
| Pin 31 | VSS — Ground reference |
| Pin 32 | VDD — Positive supply voltage |
| Pin 33 | RD0/PSP0 — PORTD bit 0 / Parallel slave port bit 0 |
| Pin 34 | RD1/PSP1 — PORTD bit 1 / Parallel slave port bit 1 |
| Pin 35 | RD2/PSP2 — PORTD bit 2 / Parallel slave port bit 2 |
| Pin 36 | RD3/PSP3 — PORTD bit 3 / Parallel slave port bit 3 |
| Pin 37 | RD4/PSP4 — PORTD bit 4 / Parallel slave port bit 4 |
| Pin 38 | RD5/PSP5 — PORTD bit 5 / Parallel slave port bit 5 |
| Pin 39 | RD6/PSP6 — PORTD bit 6 / Parallel slave port bit 6 |
| Pin 40 | RD7/PSP7 — PORTD bit 7 / Parallel slave port bit 7 |
Typical Applications
PIC18F4221-I/P is suitable for 7 applications: Industrial Control Panels, Sensor Signal Conditioning Hubs, Low-End DC Motor Control, Home Appliance Controllers, HVAC Thermostats, Educational and Hobbyist Projects, Automotive Body Electronics (Non-Safety).
Industrial Control Panels
The PIC18F4221-I/P's 36 digital I/O pins, 13-channel 10-bit ADC, and 2 CCP/PWM channels allow direct interface to pushbuttons, keypads, LED indicators, optocoupler-isolated inputs, and relay-driver outputs in industrial control panels. The -40C to +85C industrial temperature range tolerates the warm enclosure environments typical of factory floor installations, and the 4.2-5.5 V supply range accepts 5 V rails with ±10% tolerance common in industrial PSUs. The 256-byte data EEPROM stores calibration constants and machine-state parameters across power cycles without external storage. Compared to a discrete logic implementation, the PIC18F4221 replaces dozens of TTL gates while keeping firmware updatable via ICSP, and unlike an FPGA it requires no vendor toolchain license.
Recommended
Sensor Signal Conditioning Hubs
The PIC18F4221-I/P's 13-channel 10-bit ADC and dual analog comparators let one MCU digitize multiple analog sensor inputs (temperature, pressure, humidity, light, position) without external multiplexer or ADC ICs. The 40 MHz core runs linearization math, filtering, and Modbus-style communications protocols while keeping interrupt latency deterministic. The MSSP peripheral configured as I2C interfaces directly to digital sensors (SHT21 humidity, ADXL345 accelerometer), while the USART handles RS-485 to a host PLC. The 256-byte EEPROM stores sensor calibration coefficients that survive brown-outs, and nanoWatt sleep modes drop idle current below 1 uA for solar or battery-powered sensor nodes. Versus a discrete op-amp front end, this MCU integrates 13 ADC channels and two comparators into one 40-pin package at less than $5 in volume.
Recommended
Low-End DC Motor Control
The PIC18F4221-I/P drives small brushed DC motors and bipolar stepper motors using its 2 CCP/PWM channels and complementary I/O pins. The 16-bit timer feeds the PWM modules at up to 40 MHz, providing 16-bit resolution PWM output for smooth torque control below 100 Hz and 10-bit PWM above 20 kHz for silent operation. Software-configurable dead-band control via CCP special-event triggers prevents shoot-through in complementary half-bridge drivers such as the DRV8871. The 13-channel ADC samples motor current via shunt resistor, enabling closed-loop current limiting. Unlike a dedicated motor controller IC, the PIC18F4221 lets the designer implement custom commutation algorithms, thermal foldback, and stall-detection routines in firmware, trading off design simplicity for flexibility at a sub-$4 unit cost in 1k quantities.
Recommended
Home Appliance Controllers
White-goods appliance controllers (washing machines, microwave ovens, dishwashers) use the PIC18F4221-I/P for keypad scanning, rotary-encoder input, LCD driving, buzzer control, and relay sequencing. The 36 I/O pins comfortably drive 7-segment displays and matrix keypads without external latch ICs. The nanoWatt sleep mode drops standby power below 100 uA to meet Energy Star standby limits, while the 256-byte EEPROM retains user settings (timers, program steps) across power cycles. The -40C to +85C operating range handles under-cabinet kitchen heat. Versus an ASIC solution, the PIC18F4221's flash memory and ICSP allow firmware updates for new compliance rules, model variants, or bug fixes without respinning the board, dramatically shortening time-to-market.
Recommended
HVAC Thermostats
The PIC18F4221-I/P runs 24 V AC-powered thermostats at 40 MHz with sufficient MIPS to drive PID control loops on temperature, humidity, and air-handler sequencing. The 13-channel 10-bit ADC reads thermistor inputs (10 kOhm NTC) with 0.1C resolution after averaging; the 2 analog comparators implement hardware-based safety cutoffs independent of the firmware loop. The MSSP/I2C master talks to EEPROM for schedule storage and to RTC chips such as the MCP79410 for timekeeping. The 256-byte on-chip data EEPROM stores setpoints and configuration. The nanoWatt idle current lets the MCU wake on RTC alarm only and spend >99% of the time in sub-uA sleep, important for hardwired 24 VAC thermostats without battery backup. The wide 4.2-5.5 V supply accommodates rectified 24 VAC rails with significant ripple.
Recommended
Educational and Hobbyist Projects
The PIC18F4221-I/P is a staple of university embedded systems courses and hobbyist electronics because its 40-pin PDIP form factor fits a standard 0.6-inch-wide DIP socket or breadboard, its ICSP header lets beginners flash firmware with a $15 PICkit 3 or PICkit 4, and its 36 I/O pins provide more than enough headroom for student projects involving LEDs, LCDs, sensors, and motor drivers. The 4 KB flash accommodates MP3-player, GPS-parser, or simple RTOS workloads while staying within beginner toolchain limits. The C compiler-friendly architecture (MPLAB XC8 free tier supports this device) lowers the learning curve for first-time embedded developers. Compared to surface-mount PIC18 variants, the DIP-40 package is hand-solderable, swappable for quick iteration, and survives repeated insertion cycles common in lab environments.
Recommended
Automotive Body Electronics (Non-Safety)
The PIC18F4221-I/P is used in non-safety automotive body modules such as seat-position controllers, mirror-adjust modules, and interior lighting drivers where its 36 I/O pins and 13-channel ADC interface directly to position sensors, switch inputs, and LED strings. The -40C to +85C operating range covers cabin-mounted applications, and the 4.2-5.5 V supply tolerates 12 V battery rails after a 5 V regulator. For under-hood or safety-critical automotive designs, Microchip recommends AEC-Q100-qualified parts such as the PIC18F45K22-I/P (with Q1 suffix) in the same 40-pin PDIP footprint; PIC18F4221-I/P itself is not AEC-Q100 qualified and should not be used in mission-critical automotive subsystems.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F4221-I/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4321-I/P | PIC18F4220-I/P | PIC18F45K22-I/P | PIC18F4520-I/P |
|---|---|---|---|---|---|
| Package | PDIP-40 (DIP-40) | PDIP-40 - same | PDIP-40 - same | PDIP-40 - same | PDIP-40 - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Flash | 4 KB | 8 KB | 4 KB | 32 KB | 32 KB |
| SRAM | 512 bytes | 512 bytes | 512 bytes | 1536 bytes | 1536 bytes |
| ADC Resolution | 10-bit | 10-bit | 10-bit | 12-bit | 10-bit |
| ADC Channels | 13 | 13 | 8 | 28 | 13 |
| Supply Voltage | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 1.8 V to 5.5 V (XLP) | 4.2 V to 5.5 V |
| Power-Saving Modes | nanoWatt | nanoWatt | Standard Run/Sleep | XLP (eXtreme Low Power) | nanoWatt |
| CCP/PWM Channels | 2 | 2 | 2 | 5 (ECCP + CCP) | 2 (1 CCP + 1 ECCP) |
Key Differentiators
- More ADC channels than the legacy PIC18F4220-I/P (vs PIC18F4220-I/P)
- Lower power consumption than PIC18F4220-I/P via nanoWatt (vs PIC18F4220-I/P)
- Smaller flash than PIC18F4321-I/P but identical peripherals (vs PIC18F4321-I/P)
- Lower ADC resolution than PIC18F45K22-I/P (vs PIC18F45K22-I/P)
Design Notes
Decouple both VDD pins (11 and 32) with a 0.1 uF ceramic capacitor placed within 5 mm of each pin, plus a single 10 uF bulk tantalum or ceramic capacitor nearby. Estimated: at 40 MHz and full I/O toggling, the PIC18F4221-I/P typically draws about 15 mA from VDD, so the 10 uF bulk cap should be sized to handle momentary inrush when peripherals switch. In battery-backed designs, route VDD to both pins through a ferrite bead and add a 100 nF cap on the MCU side to suppress switching noise from the rest of the board.
Estimated: at 5.0 V VDD, 40 MHz CPU clock, all peripherals active, and 36 I/O pins sourcing 25 mA each, the PIC18F4221-I/P in PDIP-40 package dissipates approximately 0.6 W. The PDIP-40 package has a theta_JA of about 50 C/W, yielding a junction-temperature rise of 30 C above ambient, well inside the -40C to +85C industrial range. No heatsink is required for typical industrial-control use, but for applications at the top of the temperature range with all I/O pins fully loaded, ensure at least 50 mm^2 of copper around the package to spread heat.
Route the ICSP signals (PGC/RB6 on pin 26, PGD/RB7 on pin 27, MCLR/VPP on pin 1) to a 6-pin header with the standard Microchip ICSP pinout so that a PICkit 3 or PICkit 4 can flash firmware in-circuit without removing the MCU. Keep the trace from MCLR to VPP short (less than 25 mm) and place a 10 kOhm pull-up on MCLR to VDD to ensure clean reset behavior. If using a crystal oscillator, place the crystal within 10 mm of OSC1/OSC2 and surround it with a ground guard ring for EMI immunity.
Do not exceed 5.5 V on any VDD pin - the PIC18F4221-I/P has no internal 5 V regulator and is not 3.3 V tolerant on I/O. For 3.3 V designs, use the PIC18LF4221-I/P variant instead. A common mistake is forgetting that PORTB internal weak pull-ups are individually configurable via the RBPU bit and the WPUB register; reading a button without enabling pull-ups results in floating input. Also note that analog inputs AN8-AN12 share pins with PORTB and require the corresponding TRISB and ANSEL bits to be cleared for digital-only operation.
When using the MSSP in SPI master mode at 40 MHz FOSC, the maximum reliable SPI clock is FOSC/4 = 10 MHz, but signal-integrity analysis on long PCB traces (greater than 50 mm) or with multiple SPI slaves may require 33 ohm series termination resistors at the SCK and SDO pins to dampen reflections. For I2C operation, the MSSP pins (RC3/SCL, RC4/SDA) are open-drain and require external pull-up resistors; choose 4.7 kOhm for 100 kHz Standard-mode and 1 kOhm to 2.2 kOhm for 400 kHz Fast-mode operation with capacitive loads above 100 pF.
Compliance Information
RoHS and lead-free compliant per Microchip product page. Not AEC-Q100 qualified - use PIC18F45K22-I/PQ1 or PIC18F4620-I/PQ1 for automotive. REACH compliance declared by Microchip.
