PIC18F2221-I/SS - 8-Bit 40MHz 4KB Flash MCU 28-SSOP | Microchip
MPN: PIC18F2221-I/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.52 | $4.52 |
| 10 | $4.07 | $40.70 |
| 100 | $3.61 | $361.00 |
| 500 | $3.16 | $1,580.00 |
| 1,000 | $2.79 | $2,790.00 |
PIC18F2221-I/SS Overview
An 8-bit PIC microcontroller is a Harvard-architecture RISC CPU designed for deterministic, low-power embedded control. Within the broader taxonomy, PIC18 sits above baseline PIC10/12/16 parts and below 16-bit dsPIC/PIC24 and 32-bit PIC32 devices. The PIC18 family adds 16-bit instructions, a hardware multiplier, linear RAM access up to 4KB and C-compiler friendly addressing, making it a workhorse for cost-sensitive real-time control applications.
Key features of the PIC18F2221-I/SS include 256 bytes of EEPROM, 512 bytes of SRAM, 25 digital I/O pins, 13 channels of 10-bit Analog-to-Digital conversion, two analog comparators, two Capture/Compare/PWM modules, a Master Synchronous Serial Port configurable as SPI or I2C, an ICD (In-Circuit Debug) interface and nanoWatt technology with multiple power-managed modes including Idle, Sleep and peripheral gating.
Technically, the PIC18F2221 combines a hardware multiplier, 8x8 hardware multiply in a single cycle and 31-level stack with 200ns instruction execution at 20 MHz (40 MHz oscillator input via 4x PLL or external). The 10-bit ADC supports up to 13 analog input channels with acquisition time programmable via software, and the MSSP peripheral provides both SPI and I2C master/slave modes. The nanoWatt power-managed modes enable typical sleep currents in the microamp range, suitable for battery-backed designs.
Typical applications for the PIC18F2221-I/SS include low-cost consumer appliances, white-goods control boards, HVAC sensor interfacing, battery chargers, security alarm panels, motor control (small DC/BLDC via PWM and comparator) and industrial sensor hubs where 5V I/O and IEC 61010-1 isolation-friendly logic levels are required.
When designing with the PIC18F2221-I/SS, allocate a minimum 0.1uF decoupling capacitor adjacent to each VDD/VSS pair and follow Microchip's Emulation/ICD connection guidelines if you intend to use the on-chip debug hardware. Devices with the same flash size but different pin count exist (PIC18F2221 = 28-pin, PIC18F4321 = 44-pin); always match the package to the PCB footprint before sourcing.
Drop-in alternatives for PIC18F2221-I/SS — 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 PIC18F2221-I/SS (same form factor and footprint) — differing in Operating Temperature, Package, Program Memory (Flash), Supply Voltage (VDD), ADC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F2221-I/SO
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PIC18F2321-I/SS
✅ Drop-In✓ In Stock
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View Datasheet →PIC18F2420-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2520-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2221-E/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2221T-I/SS
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18LF2221-I/SS
✅ Drop-In✓ In Stock
$2.02 / Unit
View Datasheet →PIC18F2221-I/SS Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit Microcontroller (MCU) |
| Architecture | PIC18 (Harvard RISC) |
| Family | PIC18F2xx1/4xx1 Enhanced Flash with nanoWatt |
| Core / Data Bus Width | 8-bit |
| Maximum CPU Speed | 40 MHz (16 MIPS) |
| Instruction Cycle Time | 200 ns at 20 MHz / 100 ns at 40 MHz |
| Program Memory (Flash) | 4 KB (2K x 16 words) |
| Data EEPROM | 256 bytes |
| Data SRAM | 512 bytes |
| I/O Pins | 25 |
| ADC | 10-bit, 13 channels |
| Comparators | 2 |
| CCP/ECCP Modules | 2 CCP |
| Serial Interfaces | 1x MSSP (SPI / I2C), AUSART |
| Supply Voltage (VDD) | 4.2 V to 5.5 V |
| Operating Temperature | -40C to +85C (Industrial, -I suffix) |
| Package | 28-SSOP (0.209 inch / 5.30 mm body width) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| On-Chip Debug | ICD (In-Circuit Debugger) |
| Program Memory Type | Flash (self-programming) |
PIC18F2221-I/SS Pin Configuration
| Pin 1 | RA0/AN0 — PORTA bit 0 / Analog input channel 0 |
| Pin 2 | RA1/AN1 — PORTA bit 1 / Analog input channel 1 |
| Pin 3 | RA2/AN2/VREF-/CVREF — PORTA bit 2 / Analog input 2 / VREF- / Comparator VREF output |
| Pin 4 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input 3 / VREF+ |
| Pin 5 | RA4/T0CKI/C1OUT — PORTA bit 4 / Timer0 clock input / Comparator 1 output |
| Pin 6 | RA5/AN4/SS/HLVDIN/C2OUT — PORTA bit 5 / Analog input 4 / SSP slave select / High/Low-Voltage detect / Comparator 2 output |
| Pin 7 | VSS — Ground reference |
| Pin 8 | OSC1/CLKI/RA7 — Oscillator input / External clock input / PORTA bit 7 |
| Pin 9 | OSC2/CLKO/RA6 — Oscillator output / Clock output / PORTA bit 6 |
| Pin 10 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 11 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 I/O |
| Pin 12 | RC2/CCP1 — PORTC bit 2 / CCP1 I/O |
| Pin 13 | RC3/SCK/SCL — PORTC bit 3 / SSP SPI clock / I2C clock |
| Pin 14 | RC4/SDI/SDA — PORTC bit 4 / SSP SPI data in / I2C data |
| Pin 15 | RC5/SDO — PORTC bit 5 / SSP SPI data out |
| Pin 16 | RC6/TX/CK — PORTC bit 6 / AUSART TX / AUSART clock |
| Pin 17 | RC7/RX/DT — PORTC bit 7 / AUSART RX / AUSART data |
| Pin 18 | VSS — Ground reference |
| Pin 19 | VDD — Positive supply (4.2 V to 5.5 V) |
| Pin 20 | RB0/AN12/INT0 — PORTB bit 0 / Analog input 12 / External interrupt 0 |
| Pin 21 | RB1/AN10/INT1 — PORTB bit 1 / Analog input 10 / External interrupt 1 |
| Pin 22 | RB2/AN8/INT2 — PORTB bit 2 / Analog input 8 / External interrupt 2 |
| Pin 23 | RB3/AN9/CCP2 — PORTB bit 3 / Analog input 9 / CCP2 I/O |
| Pin 24 | RB4/AN11/KBI0 — PORTB bit 4 / Analog input 11 / Keyboard interrupt 0 |
| Pin 25 | RB5/KBI1/PGM — PORTB bit 5 / Keyboard interrupt 1 / LVP programming |
| Pin 26 | RB6/KBI2/PGC — PORTB bit 6 / Keyboard interrupt 2 / ICD clock |
| Pin 27 | RB7/KBI3/PGD — PORTB bit 7 / Keyboard interrupt 3 / ICD data |
| Pin 28 | VDD — Positive supply (4.2 V to 5.5 V) |
Typical Applications
PIC18F2221-I/SS is suitable for 6 applications: White Goods and Home Appliance Control, HVAC and Building Automation Sensors, Industrial Sensor Hubs and IoT Gateways, Battery Chargers and Power Tools, Security and Alarm Panels, Small DC/BLDC Motor Control.
White Goods and Home Appliance Control
The PIC18F2221-I/SS is widely deployed in washing machines, dishwashers, refrigerators and microwave ovens where 5V digital I/O and 28-pin SSOP integration are standard. Its 25 digital I/O pins support keypad scanning, relay drivers, triac firing, buzzer PWM and segment-LCD control via external drivers; the 13-channel 10-bit ADC reads temperature sensors (NTC/PTC), water-level probes and humidity sensors. The PIC18 core executes household real-time control loops deterministically at 40 MHz / 16 MIPS, while nanoWatt sleep currents extend standby power budgets to <2 mW per board to meet Energy Star. The 4KB Flash holds typical appliance state machines and safety interlock firmware; the 256-byte EEPROM retains user preferences and fault logs across power cycles.
Recommended
HVAC and Building Automation Sensors
In HVAC wall thermostats, indoor air-quality stations and variable-air-volume controllers, the PIC18F2221-I/SS acts as the central node that digitizes thermistor inputs, CO2/VOC sensor analog channels and occupancy-detector outputs while driving triac-controlled fan stages and communicating over RS-485 or I2C. The 13-channel 10-bit ADC provides 0.5C temperature resolution with proper averaging, and the 256-byte EEPROM stores calibration constants. The MSSP module can be configured as I2C master to scan sensor backbones; nanoWatt idle/sleep modes reduce average supply current to <100 uA for battery-backed wireless sensor variants. The 28-SSOP package suits compact wall-plate enclosures with vertical mounting.
Recommended
Industrial Sensor Hubs and IoT Gateways
The PIC18F2221-I/SS is suitable for low-cost industrial 4-20 mA / 0-10 V sensor hubs that aggregate analog inputs from a few field sensors and forward data via RS-485 or Modbus RTU to a PLC. The PIC18 RISC core delivers deterministic 100 ns instruction timing required for tight sensor sampling loops, while 13 ADC channels support a typical 8-sensor scan plus 5 housekeeping inputs. The AUSART module implements Modbus RTU slave without DMA load, and the 256-byte EEPROM retains Modbus address and calibration across maintenance. The 28-SSOP package supports dense PCB layouts where mechanical footprint is constrained; the -40C to +85C industrial grade supports cabinet or panel-mount environments.
Recommended
Battery Chargers and Power Tools
Cordless-drill and Li-ion battery charger designs use the PIC18F2221-I/SS to perform CC/CV charge algorithms, monitor cell voltage via the 10-bit ADC, drive MOSFET half-bridges via the two CCP PWM channels, and signal LED status through the digital I/O. The 4KB Flash holds typical NiMH, Li-ion and lead-acid charge profiles; the 256-byte EEPROM saves battery cycle count and pack health data. nanoWatt sleep currents minimize standby drain on the battery pack, and the 40 MHz CPU allows synchronous current-mode control loop execution within a few microseconds. The 28-SSOP package fits inside charger base enclosures with the MCU and analog front-end on a single PCB.
Recommended
Security and Alarm Panels
PIC18F2221-I/SS-based security panels implement PIR motion detector scanning via ADC, magnetic-contact zone monitoring on digital I/O, piezo-buzzer alarm drive via PWM and key-fob signal decoding on the AUSART or external interrupt. The 25 I/O pins support 8 zones plus a 4x4 keypad matrix and strobe/LED drivers, while 256 bytes EEPROM stores installer configuration and event logs across power failures. The PIC18 deterministic interrupt response (<100 ns) ensures no missed events even during busy serial housekeeping. The 28-SSOP package suits slim wall-mounted enclosures; nanoWatt sleep mode extends battery backup life to >5 years in typical alarm duty cycles.
Recommended
Small DC/BLDC Motor Control
Small BLDC or DC motor controllers for fans, pumps and toys use the PIC18F2221-I/SS to generate complementary PWM via the two CCP channels, drive MOSFET gate signals on the digital I/O, read back-EMF or shunt current via the 10-bit ADC, and implement closed-loop speed control. The 40 MHz / 16 MIPS throughput allows 20 kHz PWM with full PID loop closure inside each commutation period. The 13 ADC channels read motor phase currents, DC bus voltage and PCB temperature; the MSSP SPI drives optional digital potentiometer or gate-driver fault monitoring. The 28-SSOP package fits inside the motor housing or controller base, and nanoWatt sleep enables standby current <1 mA.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F2221-I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F2321-I/SS | PIC18F2420-I/SS | PIC18F2520-I/SS | PIC18F2221-E/SS | PIC18LF2221-I/SS |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SSOP (5.30 mm) | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same |
| Program Flash | 4 KB | 8 KB (+100%) | 16 KB (+300%) | 32 KB (+700%) | 4 KB (identical) | 4 KB (identical) |
| Data EEPROM | 256 B | 256 B | 256 B | 1 KB | 256 B | 256 B |
| Data SRAM | 512 B | 512 B | 768 B | 1.5 KB | 512 B | 512 B |
| Maximum Clock | 40 MHz / 16 MIPS | 40 MHz / 16 MIPS | 40 MHz / 16 MIPS | 40 MHz / 16 MIPS | 40 MHz / 16 MIPS | 40 MHz / 16 MIPS |
| ADC Channels | 13x 10-bit | 13x 10-bit (same) | 10x 10-bit | 10x 10-bit | 13x 10-bit (same) | 13x 10-bit (same) |
| VDD Range | 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 | 4.2 V to 5.5 V | 2.0 V to 5.5 V |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +125C (Extended) | -40C to +85C |
Key Differentiators
- Smallest-Flash, lowest-cost entry point of the PIC18F2x21 28-SSOP family (vs PIC18F2321-I/SS)
- Same 28-SSOP footprint as PIC18F2420 and PIC18F2520 for free firmware upgrades (vs PIC18F2520-I/SS)
- Industrial temperature range at standard cost; extended range available as -E variant (vs PIC18F2221-E/SS)
- Higher VDD range vs LF variant supports 5V-only systems (vs PIC18LF2221-I/SS)
Design Notes
Place a 0.1 uF X7R ceramic decoupling capacitor within 5 mm of each VDD/VSS pair (pins 19/18 and 28/18). Add a bulk 10 uF tantalum or aluminum-polymer capacitor at the regulator output to suppress Icc transient dips during CCP/PWM switching. The PIC18F2221 will draw up to 35 mA at 40 MHz; ensure the regulator can deliver at least 2x peak current for cold-start Flash programming.
Keep the 28-SSOP PCB footprint to JEDEC standard land pattern with 0.65 mm pin pitch. Route the MCLR/VPP reset line with a 10 kohm pull-up to VDD and a 100 nF capacitor to ground to enable in-circuit serial programming (ICSP). Reserve 0.1 inch-pitch test points for PGD (pin 27) and PGC (pin 26) to allow debug ICD connection without removing the IC from the board.
Keep analog ADC inputs (RA0-RA5, RB0-RB2) away from high-current switching traces such as PWM outputs on RC1/RC2 and the DC bus. Use a single-point ground at the MCU's VSS pin and route noisy return currents (MOSFET gate drive, relay coils) through a separate ground plane region. If using the internal 4x PLL, place a 100 nF capacitor across the OSC1/OSC2 pins as datasheet section 3.0 indicates for crystal operation.
Do not confuse the -I/SS suffix (industrial temp / SSOP package) with -E/SS (extended temp / SSOP) or -I/SO (industrial temp / SOIC package). Verify ordering code with Microchip's part-number decoder before procuring - mismatches will result in non-pinout-compatible SSOP vs SOIC shipments. Also note that the LF (low-voltage) variants require different programming voltages than standard F parts.
For I2C bus operation via MSSP, place 4.7 kohm pull-ups on SCL (RC3) and SDA (RC4); for SPI master operation, ensure the SCK signal integrity by routing over a continuous ground plane. The AUSART TX/RX pins (RC6/RC7) are 5V TTL-level; for RS-485 add an external transceiver such as MCP2551. Always keep MCLR high during operation to avoid spurious resets.
Compliance Information
RoHS-compliant lead-free matte-tin finish per Microchip product declaration. Halogen-free per Microchip statement. AEC-Q100 qualification is not applicable to this general-purpose MCU; for automotive AEC-Q100 use the PIC18Fxxx-I/SS variant. REACH SVHC compliance is maintained per Microchip's chemical substance declarations.
