PIC18C242-I/SO - 8-bit 40MHz OTP MCU, 16KB, 28-SOIC | Microchip
MPN: PIC18C242-I/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.2 | $5.20 |
| 10 | $4.65 | $46.50 |
| 100 | $4.1 | $410.00 |
| 500 | $3.62 | $1,810.00 |
| 1,000 | $3.2 | $3,200.00 |
PIC18C242-I/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, non-volatile program memory (Flash/ROM/OTP), volatile working RAM, peripheral blocks (ADC, timers, UART, SPI, I2C), and general-purpose I/O into one package. Within the broader taxonomy, an MCU sits inside the semiconductor -> integrated circuit -> microcontroller -> 8-bit microcontroller hierarchy. The PIC18C family adds enhanced 16-bit-wide instructions, a hardware multiplier, and C-friendly architecture to the classic PIC baseline, making it a stepping stone to the later PIC18F Flash-based parts. Program memory is One-Time Programmable (OTP), meaning each unit can be programmed once but cannot be electrically erased; this is suitable for low-volume production, educational use, and end products that do not need firmware updates.
Key features include 16 KB OTP program memory, 512 B SRAM, 23 I/O, a 10-bit 5-channel ADC, a USART, an SSP (SPI/I2C) module, two 8-bit timers plus one 16-bit timer, and an internal/external oscillator block. The wide 28-SOIC footprint simplifies hand-soldering and breadboard prototyping compared to surface-mount-only packages. The architecture offers 77 single-word instructions, a hardware 8x8 multiplier, and 16-bit instructions that improve C code density, while the 10-bit ADC supports up to 5 analog inputs on the 28-pin device.
Typical applications include industrial control loops, motor drive signal conditioning, sensor interfacing with on-chip ADC, embedded educational platforms, low-volume OEM controllers, and legacy product refresh designs where the proven PIC18C instruction set and toolchain are retained. Because the PIC18C line has been superseded by the PIC18F family (notably the recommended PIC18F242), designers should weigh future firmware-iteration needs and supply availability before committing to OTP memory.
Drop-in alternatives for PIC18C242-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 PIC18C242-I/SO (same form factor and footprint) — differing in Package, ADC, Mounting Type, Core Architecture, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F242-I/SO
✅ Drop-In✓ In Stock
$3.5 / Unit
View Datasheet →PIC18F242T-I/SO
✅ Drop-In✓ In Stock
$4.65 / Unit
View Datasheet →PIC18F242-E/SO
✅ Drop-In✓ In Stock
$5.95 / Unit
View Datasheet →PIC18F242-I/SP
✅ Drop-In✓ In Stock
$5.3 / Unit
View Datasheet →PIC18C242-I/SO Maximum Ratings & Electrical Characteristics
| Series | PIC 18C |
| Core | PIC |
| Core Size | 8-bit |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 16 KB (8K x 16) |
| RAM Size | 512 B |
| EEPROM | 0 B (not present on this family) |
| Maximum Clock Frequency | 40 MHz (10 MIPS) |
| Number of I/O Pins | 23 |
| ADC | 10-bit, 5 channels |
| Timers | 2 x 8-bit + 1 x 16-bit |
| Communication Interfaces | USART, SSP (SPI/I2C) |
| Oscillator Type | External |
| Operating Voltage | 4.2 V to 5.5 V |
| Operating Temperature | -40C to +85C (Industrial) |
| Package | 28-SOIC wide-body, 7.50 mm |
| Mounting Type | Surface Mount |
| Instruction Set | 77 single-word instructions, 16-bit opcode |
| Multiplier | Hardware 8 x 8 |
| MSL Level | 1 (unlimited floor life at <30C/85% RH) |
PIC18C242-I/SO Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (reset) input / programming voltage |
| Pin 2 | RA0/AN0 — Digital I/O / analog input AN0 |
| Pin 3 | RA1/AN1 — Digital I/O / analog input AN1 |
| Pin 4 | RA2/AN2 — Digital I/O / analog input AN2 |
| Pin 5 | RA3/AN3/VREF+ — Digital I/O / analog input AN3 / ADC VREF+ |
| Pin 6 | RA4/T0CKI — Digital I/O / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — Digital I/O / analog input AN4 / SPI slave select |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKIN — Crystal oscillator input / external clock input |
| Pin 10 | OSC2/CLKOUT — Crystal oscillator output / clock output |
| Pin 11 | RC0/T1OSO/T1CKI — Digital I/O / Timer1 oscillator output / Timer1 clock |
| Pin 12 | RC1/T1OSI/CCP2 — Digital I/O / Timer1 oscillator input / Capture-Compare-PWM 2 |
| Pin 13 | RC2/CCP1 — Digital I/O / Capture-Compare-PWM 1 |
| Pin 14 | RC3/SCK/SCL — Digital I/O / SPI clock / I2C clock |
| Pin 15 | RC4/SDI/SDA — Digital I/O / SPI data in / I2C data |
| Pin 16 | RC5/SDO — Digital I/O / SPI data out |
| Pin 17 | RC6/TX/CK — Digital I/O / USART TX / USART clock |
| Pin 18 | RC7/RX/DT — Digital I/O / USART RX / USART data |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage (4.2-5.5 V) |
| Pin 21 | RB0/INT0 — Digital I/O / external interrupt 0 |
| Pin 22 | RB1/INT1 — Digital I/O / external interrupt 1 |
| Pin 23 | RB2/INT2 — Digital I/O / external interrupt 2 |
| Pin 24 | RB3/CCP2 — Digital I/O / Capture-Compare-PWM 2 |
| Pin 25 | RB4 — Digital I/O |
| Pin 26 | RB5 — Digital I/O |
| Pin 27 | RB6/PGC — Digital I/O / ICSP clock |
| Pin 28 | RB7/PGD — Digital I/O / ICSP data |
Typical Applications
PIC18C242-I/SO is suitable for 7 applications: Industrial Sensor Interface Controller, Motor Drive Signal Conditioning, Embedded Educational Platform, Low-Volume OEM Replacement Controller, USART Bridge / Protocol Converter, Battery Charger Control Logic, Lighting Control and DMX Nodes.
Industrial Sensor Interface Controller
The PIC18C242-I/SO fits industrial sensor interface boards where 23 digital I/O and a 10-bit 5-channel ADC are sufficient to read multiple analog sensors (temperature, pressure, level) and drive digital actuators or relays. At 40 MHz / 10 MIPS the core can service SPI/I2C sensor polling, USART comms to a host PLC, and periodic ADC conversions well within typical 1 ms control loops. The wide 4.2-5.5 V supply matches 5 V industrial backplanes; OTP memory is acceptable for fixed-logic sensors shipped without firmware updates.
Recommended
Motor Drive Signal Conditioning
In low-voltage motor control signal-conditioning cards, the PIC18C242-I/SO's 10-bit ADC samples current/voltage feedback while the 16-bit timer generates PWM reference waveforms for a downstream gate driver. The hardware 8x8 multiplier accelerates Park/Clark transforms in scalar or simple vector control loops. The 28-SOIC footprint allows generous copper pours for thermal management; OTP memory locks the control law once the design is qualified, removing field-reprogramming concerns.
Recommended
Embedded Educational Platform
The PIC18C242-I/SO is well suited to university and vocational training labs: 16 KB of OTP program memory holds a complete C-coded curriculum example (UART printf, ADC scanning, timer interrupts), while the 28-SOIC wide-body package is hand-solderable for student-built PCBs. The C-friendly PIC18 instruction set with 77 single-word instructions lets beginners focus on algorithms rather than assembly; toolchains like MPLAB X with XC8 are well documented for this silicon.
Recommended
Low-Volume OEM Replacement Controller
Many legacy appliances, HVAC peripherals, and access-control boards used PIC18C242-I/SO in their original design. For low-volume replacement or refurbishment, the PIC18C242-I/SO can be dropped onto the same 28-SOIC footprint and programmed once with the legacy firmware image. Its 4.2-5.5 V operation matches common 5 V rails, and the 23 I/O pins map cleanly to typical 5 V logic-level peripherals.
Recommended
USART Bridge / Protocol Converter
The PIC18C242-I/SO's USART plus SSP (SPI/I2C) make it a natural fit for low-cost protocol-converter cards that bridge a legacy RS-232 host to an I2C or SPI sensor cluster. At 40 MHz the core can sustain 115200 baud serial traffic while polling multiple I2C slaves; 512 B of RAM is sufficient for short buffers. OTP memory ensures the converter logic is locked at production.
Recommended
Battery Charger Control Logic
For simple NiCd/NiMH or lead-acid charger boards, the PIC18C242-I/SO monitors charge current and battery voltage through its 10-bit ADC and toggles charge/float FETs through GPIO. The hardware 8x8 multiplier accelerates Wh-counting routines, while the 16-bit timer supports precise charge-cycle timing. The 28-SOIC package handles moderate thermal dissipation at modest switching currents.
Recommended
Lighting Control and DMX Nodes
DMX512 lighting nodes, architectural dimmers, and stage-effect controllers commonly use 8-bit PIC MCUs like the PIC18C242-I/SO to receive DMX frames over a high-speed USART and drive PWM dimming outputs for LED or incandescent fixtures. The 40 MHz clock supports 250 kbaud DMX reception reliably, and the 23 I/O pins handle multiple PWM channels plus an address-encoder DIP switch input.
Recommended
Recommended Products Summary
Engineering reference data for PIC18C242-I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F242-I/SO | PIC18F242T-I/SO | PIC18F242-E/SO |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC (wide-body) | 28-SOIC (wide-body) - same | 28-SOIC (wide-body) - same | 28-SOIC (wide-body) - same |
| Program Memory Type | 16 KB OTP | 16 KB Flash | 16 KB Flash | 16 KB Flash |
| RAM | 512 B | 512 B | 512 B | 512 B |
| I/O Pins | 23 | 23 | 23 | 23 |
| Max Clock | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) |
| Temperature Range | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +125C (Extended) |
| ADC | 10-bit, 5 channels | 10-bit, 5 channels | 10-bit, 5 channels | 10-bit, 5 channels |
| Communication Interfaces | USART, SSP (SPI/I2C) | USART, SSP (SPI/I2C) | USART, SSP (SPI/I2C) | USART, SSP (SPI/I2C) |
| Lifecycle | Obsolete (OTP) | Active (Flash) | Active (Flash, T&R) | Active (Flash, Extended temp) |
Key Differentiators
- OTP program memory locks firmware at production (vs PIC18F242-I/SO)
- Same 28-SOIC wide-body pinout as recommended Flash replacement (vs PIC18F242-I/SO)
- Hardware 8x8 multiplier accelerates C math (vs PIC16F series)
Design Notes
Because the PIC18C242-I/SO uses OTP program memory, every firmware bug becomes a permanent unit cost. Always program production parts on a final, fully-tested firmware image; do not use OTP devices for development. Use the PIC18F242-I/SO or a Flash-based PIC18F sibling during development and only switch to OTP for the locked production bill of materials. Verify configuration bits (oscillator, watchdog, brown-out) before ordering production programmers.
The PIC18C242-I/SO operates strictly from 4.2 V to 5.5 V; there is no wide-voltage 2.0-5.5 V operation typical of later PIC18F parts. Add a 100 nF decoupling capacitor as close as possible to the VDD pin (pin 20) and a bulk 10 uF tantalum or ceramic near the supply entry; the 28-SOIC wide-body pin pitch permits short, low-inductance traces for the decoupling cap. For ADC accuracy, drive VREF+ from a clean reference such as a TL431 rather than the noisy VDD rail.
OSC1/OSC2 crystal traces must be kept short and surrounded by a ground guard ring to reduce EMI and improve oscillator start-up margin. For high-speed USART at 115200 baud or above, place the MAX232 or SN75176 transceiver close to the RC6/RC7 pins to keep the trace short; route the analog AN0-AN4 traces away from digital switching lines to minimize ADC crosstalk on the 10-bit ADC.
Compliance Information
Lead-free and RoHS compliance not explicitly confirmed in the verified web data - verify against the manufacturer datasheet and product label. PIC18C is an older OTP family predating widespread automotive AEC-Q100 qualification; for automotive applications use a PIC18F variant explicitly qualified to AEC-Q100.
