PIC18F242-I/SO - 8-Bit 40MHz 16KB Flash MCU | Microchip | 28-SOIC
MPN: PIC18F242-I/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.85 | $5.85 |
| 10 | $5.2 | $52.00 |
| 100 | $4.55 | $455.00 |
| 500 | $3.95 | $1,975.00 |
| 1,000 | $3.5 | $3,500.00 |
PIC18F242-I/SO Overview
What is an 8-bit flash microcontroller? An 8-bit flash microcontroller is a single-chip computer that combines a CPU with 8-bit data width, on-chip non-volatile flash program memory, SRAM data memory, and a rich set of peripherals (ADC, timers, communication interfaces). Within the broader taxonomy, the PIC18F242 belongs to: 8-bit MCU -> microcontroller -> embedded controller -> semiconductor IC. PIC18F parts use an enhanced Harvard architecture with separate program and data buses, enabling simultaneous instruction fetch and operand access, which delivers higher throughput than von Neumann 8-bit cores at the same clock speed.
Key differentiating features of the PIC18F242 include nanoWatt power management with multiple idle and sleep modes, on-chip in-circuit debug (ICD) support, 100 ns instruction execution, and self-programming capability that allows the device to write its own flash under firmware control. The wide 4.2 V to 5.5 V supply range and -40 C to +85 C industrial temperature grade make it suitable for both battery-tolerant and industrial environments.
Architecturally, the PIC18F242 uses a 16-bit instruction word with 8-bit data path and provides 77 single-word instructions plus an additional 8 high-priority interrupts. The Harvard split bus allows flash access during any instruction cycle without wait states, providing deterministic execution critical for real-time control loops. The integrated ADC has 10-bit resolution and accepts analog inputs on shared digital I/O pins.
Typical applications include industrial control systems, automotive body and chassis modules (non-safety), consumer appliance control, low-cost sensor signal conditioning, and hobbyist embedded platforms. The PIC18F242 is also widely used in legacy designs, educational platforms, and PIC18F upgrade replacements where larger flash variants are unavailable.
When designing with the PIC18F242, leave a small guard band on VDD (typically 4.5 V to 5.5 V) for reliable ADC operation and decouple the analog and digital supply pins separately. Programming is via ICSP using PGC/PGD pins shared with PORTB, so verify those traces are not heavily loaded for stable in-circuit programming.
This page synthesizes current distributor pricing, pin-compatible drop-in alternatives, and practical design notes not aggregated on the manufacturer datasheet.
Drop-in alternatives for PIC18F242-I/SO — 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 PIC18F242-I/SO (same form factor and footprint) — differing in Package, Core Architecture, Mounting Type, ADC, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F252-I/SO
✅ Drop-In✓ In Stock
$3.95 / Unit
View Datasheet →PIC18F242-I/SP
✅ Drop-In✓ In Stock
$5.3 / Unit
View Datasheet →PIC18F242T-I/SO
✅ Drop-In✓ In Stock
$4.65 / Unit
View Datasheet →PIC18F242-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2420-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F23K22-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F242-I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18F (Enhanced Harvard, 8-bit data, 16-bit instruction word) |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Program Flash Memory | 16 KB (8K x 16) |
| SRAM | 768 bytes |
| EEPROM | 256 bytes |
| Digital I/O Pins | 23 (with 25 I/O ports per datasheet nomenclature) |
| ADC | 5 channels, 10-bit |
| Capture/Compare/PWM Modules | 2 (CCP) |
| Serial Interfaces | 1x SSP (configurable SPI or I2C), USART |
| Supply Voltage (VDD) | 4.2 V to 5.5 V |
| Operating Temperature | -40 C to +85 C (Industrial, -I suffix) |
| Instruction Set | 77 single-word instructions |
| Self-Programming | Yes (flash self-write under firmware) |
| In-Circuit Debug | Yes (ICD via PGC/PGD) |
| Power-Saving Modes | nanoWatt: Idle, Sleep, and multiple low-power modes |
| Package | 28-pin SOIC (SO), 7.50 mm body width |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant (SO package) |
PIC18F242-I/SO Pin Configuration
| Pin 1 | MCLR — Master Clear (reset) input, active low |
| 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 VREF- |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / analog input 3 / ADC VREF+ |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / analog input 4 / SPI slave select |
| Pin 8 | OSC1/CLKI — Crystal oscillator input / external clock input |
| Pin 9 | OSC2/CLKO — Crystal oscillator output / clock output |
| 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 |
| Pin 12 | RC2/CCP1 — PORTC bit 2 / CCP1 |
| Pin 13 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 14 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 15 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 16 | RC6/TX/CK — PORTC bit 6 / USART TX / USART clock |
| Pin 17 | RC7/RX/DT — PORTC bit 7 / USART RX / USART data |
| Pin 18 | VSS — Ground reference |
| Pin 19 | VDD — Positive supply voltage (4.2 V to 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 alternate |
| Pin 24 | RB4 — PORTB bit 4 (interrupt-on-change) |
| Pin 25 | RB5/PGM — PORTB bit 5 / LVP programming |
| Pin 26 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 27 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 28 | AVDD — Analog supply (tie to VDD) |
Typical Applications
PIC18F242-I/SO is suitable for 7 applications: Industrial Control Systems, Consumer Appliance Control, Automotive Body and Chassis Modules, Sensor Signal Conditioning Hubs, Educational and Hobbyist Embedded Platforms, Legacy PIC16C/16F Upgrade Replacement, Smart Sensor / IoT Edge Nodes.
Industrial Control Systems
The PIC18F242-I/SO suits industrial control panels and PLC I/O modules because its 40 MHz / 10 MIPS core executes PID control loops in under 1 ms, and the 5-channel 10-bit ADC reads 4-20 mA process signals directly through external sense resistors. Its 4.2 V to 5.5 V supply range tolerates 24 V industrial rails stepped down by switching pre-regulators, while the -40 C to +85 C industrial grade handles factory-floor thermal swings. Two CCP modules deliver complementary PWM for motor or solenoid control, and the 23 I/O pins drive relay coils, opto-isolators, and status LEDs without external logic. The on-chip EEPROM stores non-volatile setpoints and calibration constants across power cycles.
Recommended
Consumer Appliance Control
The PIC18F242-I/SO is well-matched to white-goods control boards (washing machines, dishwashers, microwave ovens) where 16 KB flash holds the main wash-cycle state machine and the 256-byte EEPROM retains user preferences across power loss. The 5-channel ADC samples temperature, water level, and motor current sensors, while the two CCP modules generate PWM for variable-speed motor drives and triac-fired heating elements. nanoWatt sleep modes drop quiescent current to single-digit microamps for standby energy compliance, important for ENERGY STAR-rated appliances. The 28-SOIC package is well-suited to conformal-coated consumer boards and wave-solder manufacturing.
Recommended
Automotive Body and Chassis Modules
The PIC18F242-I/SO handles non-safety body electronics such as seat controllers, mirror adjusters, lighting modules, and HVAC blend-door actuators where cost targets favor 8-bit cores over 16-bit. Its 40 MHz core and 2 CCP modules drive PWM motor signals with 10-bit resolution sufficient for positioning loops, and the 5-channel ADC reads position feedback from potentiometers or Hall sensors. The -40 C to +85 C industrial temperature grade covers cabin-mounted modules; for under-hood or AEC-Q100 required applications, designers should select an automotive-grade part. The 256-byte EEPROM stores seat position memory and trim calibration across battery disconnects.
Recommended
Sensor Signal Conditioning Hubs
The PIC18F242-I/SO is a strong fit for multi-sensor data acquisition nodes that aggregate signals from thermocouples, RTDs, strain gauges, and 4-20 mA loops in process instrumentation. The 10-bit ADC across 5 channels delivers 0.1% full-scale resolution - adequate for general-purpose sensor readout - while the 23 digital I/O pins drive sensor excitation switches and read digital sensors. The 768-byte SRAM buffers raw samples before averaging, and the 256-byte EEPROM stores calibration coefficients. The MSSP peripheral configurable as SPI or I2C talks to external ADCs, DACs, or EEPROM for higher-precision subsystems, and the USART links to RS-485 transceivers for industrial network connectivity.
Recommended
Educational and Hobbyist Embedded Platforms
The PIC18F242-I/SO is widely used in university embedded systems courses and hobbyist projects because the PIC18 instruction set is well-documented, the MPLAB X IDE with XC8 compiler is free, and the PICkit programmers offer an inexpensive debug path. Its 16 KB flash accommodates multi-module coursework projects (ADC, PWM, UART, I2C, interrupts), and the 28-SOIC package fits on standard 0.1-inch prototyping adapters. ICD support via PGC/PGD pins allows real-time breakpoint debugging without extra hardware, a critical feature for student learning workflows. The nanoWatt power modes also let students explore battery-powered embedded design.
Recommended
Legacy PIC16C/16F Upgrade Replacement
The PIC18F242-I/SO is a common upgrade path for legacy PIC16C5X, PIC12CXXX, and PIC16CXX designs where the original parts are obsolete or have insufficient flash. Its enhanced instruction set is a superset of the PIC16 instruction set, and the 77 single-word instruction set is upwards compatible with PIC16CXX per the Microchip PIC18Fxx2 datasheet. Designers can reuse existing PCB footprints (28-pin SOIC) while gaining flash self-programming, ICD debug, and nanoWatt power modes. The wider 4.2 V to 5.5 V supply range also accommodates legacy 5 V rails without redesign.
Recommended
Smart Sensor / IoT Edge Nodes
The PIC18F242-I/SO suits cost-sensitive IoT edge nodes that read local sensors, perform simple on-device processing, and report over UART or SPI to a host radio module. Its 16 KB flash accommodates lightweight protocol stacks and edge filtering code, while 768 bytes of SRAM buffers sensor samples before transmission. The 5-channel ADC reads analog environmental sensors (temperature, humidity, light), and the nanoWatt sleep mode drops supply current below 1 uA in deep sleep for battery years of operation on coin cells. The ICSP debug path also enables OTA firmware development workflows for production test and field update.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F242-I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F252-I/SO | PIC18F242-I/SP | PIC18F242T-I/SO | PIC18F2420-I/SO | PIC18F23K22-I/SO |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC | 28-SOIC - same | 28-SPDIP - same pinout, through-hole | 28-SOIC - same | 28-SOIC - same | 28-SOIC - same |
| Program Flash | 16 KB | 32 KB | 16 KB | 16 KB | 16 KB | 8 KB |
| SRAM | 768 B | 1536 B | 768 B | 768 B | 768 B | 512 B |
| EEPROM | 256 B | 256 B | 256 B | 256 B | 256 B | 256 B |
| Max CPU Speed | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 64 MHz (16 MIPS) |
| ADC Channels / Resolution | 5 / 10-bit | 5 / 10-bit | 5 / 10-bit | 5 / 10-bit | 11 / 10-bit | 19 / 10-bit |
| Operating 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 5.5 V | 2.3 V to 5.5 V |
| Unit Price (qty 1, USD) | ~$5.85 | ~$6.20 | ~$5.50 | ~$5.85 | ~$5.10 | ~$2.80 |
Key Differentiators
- Established PIC18 instruction-set compatibility for legacy upgrades (vs PIC18F23K22-I/SO)
- Better stock availability and lower entry price for hobbyist scale (vs PIC18F2420-I/SO)
- Direct drop-in doubling of flash and SRAM (vs PIC18F252-I/SO)
Design Notes
Estimated: at VDD = 5.0 V and a 40 MHz CPU running flat-out, the PIC18F242 core draws roughly 16 mA active per Microchip datasheet typical curves, with peripherals adding a few mA. For battery-powered designs budget at least 20 mA peak active current and budget a low-dropout regulator with 50 mA headroom. Use the nanoWatt Sleep mode (below 1 uA typical) when the application is mostly idle - wake from interrupt or WDT to stretch battery life into years.
Place a 0.1 uF decoupling capacitor within 5 mm of the VDD pin (pin 19) and another 0.1 uF close to AVSS/AVDD (pin 28 in SOIC-28). The analog supply pin must be tied directly to VDD, not through a ferrite, to keep ADC reference noise below 1 LSB. Keep the MCLR pull-up resistor (typically 10 kohm) close to the IC and avoid routing long MCLR traces near switching signals - long MCLR traces pick up noise and cause spurious resets in industrial environments.
PIC18F242 cannot be debugged if PGC (RB6) or PGD (RB7) are repurposed as outputs driving heavy loads. Always configure RB6 and RB7 as inputs or high-impedance during reset so ICSP can handshake, otherwise programming fails. Also note that PIC18F2xxx parts without the 'A' suffix require MCLR tied to VDD through a resistor; leaving MCLR floating is the most common cause of 'dead' PIC18F2xxx units at first power-up.
Route the crystal traces (OSC1/OSC2) short and symmetric, with a ground plane cutout underneath to minimize capacitive loading. For 40 MHz operation, keep crystal traces under 5 mm and place load capacitors within 3 mm of the oscillator pins. If using an external clock module, drive OSC1 with a CMOS-level source and leave OSC2 floating - never short OSC2 to ground when using an external clock.
The MSSP peripheral in I2C mode uses open-drain outputs on RC3/RC4 and requires external pull-up resistors (typically 2.2 kohm to 10 kohm depending on bus speed and capacitance). For 400 kHz I2C with > 20 cm bus length, use 2.2 kohm pull-ups and verify rise time with a scope. For SPI at 10 MHz, keep bus capacitance under 30 pF total by limiting slave count and trace length; otherwise add 22 ohm series damping resistors at the SCK source.
Compliance Information
SOIC-28 package is RoHS compliant per Microchip product page. Industrial temperature grade (-I) only - not AEC-Q100 qualified; for automotive applications select a Q-grade or AEC-Q100 part. Halogen-free status not explicitly stated in provided data - set to unknown.
