PIC18C242/JW - 40MHz 8-Bit MCU, 16KB EPROM, 28-CerDIP Window | Microchip
MPN: PIC18C242/JW ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.5 | $18.50 |
| 10 | $16.2 | $162.00 |
| 100 | $14 | $1,400.00 |
| 500 | $12.1 | $6,050.00 |
| 1,000 | $10.5 | $10,500.00 |
PIC18C242/JW Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory, data RAM, and peripherals on one die. The PIC18C architecture belongs to the enhanced mid-range family, sitting above the PIC16 baseline and below the dsPIC/PIC24 16-bit families in Microchip's taxonomy: 8-bit MCU -> RISC microcontroller -> embedded controller -> semiconductor. The PIC18C core uses a Harvard architecture with separate program and data buses, an 8-bit data path, and a 16-bit instruction word. This dual-bus design lets the CPU fetch instructions while reading/writing data in the same clock cycle, yielding the 40MHz (10 MIPS) throughput.
Key features include 16KB EPROM program memory, 768 bytes of data RAM, a 5-channel 8-bit ADC, synchronous/asynchronous serial ports (USART), MSSP for SPI/I2C, capture/compare/PWM modules, and 23 digital I/O pins. The windowed CerDIP package supports development via UV erasure (~20 minutes under 254nm UV lamp).
Typical applications include embedded control systems, sensor interfaces, motor control, industrial automation, and legacy product maintenance where windowed parts enable field re-programming. The through-hole 28-CDIP form factor suits breadboard prototypes, educational platforms, and aerospace/defense legacy sustainment programs.
When designing with this part, note that the PIC18C series has been superseded by the flash-based PIC18F family (e.g., PIC18F242). The windowed JW variant is generally used only for development; production designs should migrate to PIC18F or PIC18F-Q1 equivalents. Always verify the silicon revision against the datasheet errata before reuse.
Drop-in alternatives for PIC18C242/JW — 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/JW (same form factor and footprint) — differing in Package, ADC, Mounting Type, Core Architecture, Timers.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18C242-I/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18C242-I/SO
✅ Drop-In✓ In Stock
$3.2 / Unit
View Datasheet →PIC18C242-E/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F242-I/SP
✅ Drop-In✓ In Stock
$5.3 / Unit
View Datasheet →PIC18F2420-I/SP
✅ Drop-In✓ In Stock
$5.22 / Unit
View Datasheet →PIC18F242-I/SO
✅ Drop-In✓ In Stock
$3.5 / Unit
View Datasheet →PIC18C242/JW Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (Harvard) |
| Program Memory Type | UV-Erasable EPROM (windowed JW package) |
| Program Memory Size | 16 KB (8K x 16 words) |
| Data RAM | 768 bytes |
| Data EEPROM | Not present (EPROM device) |
| Maximum CPU Frequency | 40 MHz (10 MIPS) |
| I/O Pins | 23 |
| ADC | 5-channel, 8-bit |
| USART | 1 x AUSART (addressable) |
| MSSP (SPI/I2C) | Yes |
| Package | 28-pin CDIP (Ceramic DIP) with UV window - 0.300 inch, 7.62mm |
| Mounting Type | Through-Hole |
PIC18C242/JW Pin Configuration
| Pin 1 | MCLR — Master Clear (reset) input, active low |
| Pin 2 | RA0/AN0 — Digital I/O / Analog input channel 0 |
| Pin 3 | RA1/AN1 — Digital I/O / Analog input channel 1 |
| Pin 4 | RA2/AN2/VREF- — Digital I/O / Analog input channel 2 / ADC VREF- |
| Pin 5 | RA3/AN3/VREF+ — Digital I/O / Analog input channel 3 / ADC VREF+ |
| Pin 6 | RA4/T0CKI — Digital I/O / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — Digital I/O / Analog input channel 4 / SPI slave select |
| Pin 8 | OSC2/CLKOUT — Oscillator output / Clock out |
| Pin 9 | OSC1/CLKIN — Oscillator input / External clock input |
| Pin 10 | RC0/T1OSO/T1CKI — Digital I/O / Timer1 oscillator output / Timer1 clock input |
| Pin 11 | RC1/T1OSI/CCP2 — Digital I/O / Timer1 oscillator input / CCP2 |
| Pin 12 | RC2/CCP1 — Digital I/O / CCP1 PWM output |
| Pin 13 | RC3/SCK/SCL — Digital I/O / SPI clock / I2C clock |
| Pin 14 | RC4/SDI/SDA — Digital I/O / SPI data in / I2C data |
| Pin 15 | RC5/SDO — Digital I/O / SPI data out |
| Pin 16 | RC6/TX/CK — Digital I/O / USART TX / USART clock |
| Pin 17 | RC7/RX/DT — Digital I/O / USART RX / USART data |
| Pin 18 | RB0/INT0 — Digital I/O / External interrupt 0 |
| Pin 19 | RB1/INT1 — Digital I/O / External interrupt 1 |
| Pin 20 | RB2/INT2 — Digital I/O / External interrupt 2 |
| Pin 21 | RB3/INT3 — Digital I/O / External interrupt 3 / PGM (low-voltage programming) |
| Pin 22 | RB4 — Digital I/O / Interrupt-on-change |
| Pin 23 | RB5 — Digital I/O / Interrupt-on-change |
| Pin 24 | RB6/PGC — Digital I/O / Interrupt-on-change / ICSP clock |
| Pin 25 | RB7/PGD — Digital I/O / Interrupt-on-change / ICSP data |
| Pin 26 | VSS — Ground reference |
| Pin 27 | VDD — Positive power supply |
| Pin 28 | VSS — Ground reference (second VSS pin) |
Typical Applications
PIC18C242/JW is suitable for 6 applications: Embedded Control Systems, Sensor Interface & Data Acquisition, Educational & Development Platforms, Motor Control & PWM Drives, Legacy Industrial Automation Sustainment, Communications & Serial Networking.
Embedded Control Systems
The PIC18C242/JW fits legacy embedded control designs where a windowed ceramic DIP enables field re-programming via UV erasure. Its 40MHz (10 MIPS) throughput, 16KB EPROM, and 23 I/O pins can drive relays, solenoids, keypad scanning, and indicator LEDs in industrial controllers. Compared to modern flash MCUs, the JW variant remains relevant only for legacy sustainment, military, or aerospace programs that require MIL-spec ceramic packaging and the ability to re-burn EPROM. The 768-byte RAM supports small RTOS-like schedulers and queue-based I/O loops. When modernizing these designs, migrate to PIC18F242-I/SP for ICSP flash reprogramming.
Recommended
Sensor Interface & Data Acquisition
The PIC18C242/JW integrates a 5-channel 8-bit ADC suitable for multi-sensor data acquisition boards, particularly in legacy laboratory instruments and field-test equipment. Each ADC channel supports a 10us+ acquisition time, and the PIC18 instruction set includes FSR-based indirect addressing suitable for circular sample buffers in 768 bytes of RAM. Its AUSART enables RS-232/RS-485 transmission to host PCs, while MSSP provides I2C/SPI connection to digital sensors. The windowed package allows firmware updates when calibration algorithms change. Modern alternatives should consider PIC18F2420 or dsPIC33EP for higher ADC resolution.
Recommended
Educational & Development Platforms
The PIC18C242/JW is widely used in university embedded-systems courses and Microchip developer training kits because its UV-erasable window lets students repeatedly program and debug code without discarding the chip. The 28-pin DIP footprint is breadboard-friendly and works with the classic PICSTART Plus and MPLAB ICD programmers. The PIC18 instruction set introduces students to Harvard architecture, banked memory, and peripheral interrupt handling, providing a stepping stone to PIC24/dsPIC. Although obsolete for production, the JW variant remains in stock for educational distributors serving EE/CE programs.
Recommended
Motor Control & PWM Drives
The PIC18C242/JW includes Capture/Compare/PWM (CCP) modules that can generate PWM signals for small DC motor control, fan speed regulation, and LED dimming. Its 40MHz clock yields PWM frequencies up to 10kHz with 10-bit resolution suitable for hobbyist robotics and small appliance drives. The 23 digital I/O pins can interface to H-bridge drivers, opto-isolators, and quadrature encoders. While the EPROM-based PIC18C242 is workable for development, production motor-control designs benefit from PIC18F2431 or dsPIC30F parts that include dedicated motor-control PWMs and quadrature encoder interfaces.
Recommended
Legacy Industrial Automation Sustainment
Many long-lifecycle industrial automation systems (textile machinery, CNC controllers, HVAC line-replaceable units) designed in the late 1990s use PIC18C242/JW parts on pluggable IC sockets for serviceability. The windowed package lets field technicians erase and re-program the firmware on the shop floor without removing the chip from the board. Aerospace, defense, and medical systems with multi-decade support requirements still source PIC18C242/JW from authorized distributors and brokers like ZD Integrated Circuits. These programs rely on the JW specifically because the socketed ceramic package is field-erasable and re-burnable.
Recommended
Communications & Serial Networking
The PIC18C242/JW's integrated addressable USART and MSSP (SPI/I2C) make it suitable for serial-communication gateways, protocol bridges, and small-scale RS-232/RS-485 multidrop nodes. Up to 25 nodes can share a single RS-485 bus, with the AUSART handling 9-bit addressing automatically. SPI master mode supports LCD displays, EEPROMs, and sensor front-ends. The 28-pin DIP form factor lets maintenance technicians swap out failed units in field cabinets. For modern industrial networks, consider migrating to PIC18F27K42 or PIC18F46K22 with built-in CAN or Ethernet peripherals.
Recommended
Recommended Products Summary
Engineering reference data for PIC18C242/JW — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18C242-I/P | PIC18C242-I/SO | PIC18C242-E/P | PIC18F242-I/SP | PIC18F2420-I/SP | PIC18F242-I/SO |
|---|---|---|---|---|---|---|---|
| Package | 28-CerDIP windowed (JW) | 28-PDIP (300 mil) - same footprint | 28-SOIC - different footprint | 28-PDIP (300 mil) - same footprint | 28-PDIP (300 mil) - same footprint | 28-PDIP (300 mil) - same footprint | 28-SOIC - different footprint |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory Type | UV-EPROM (windowed) | OTP EPROM | OTP EPROM | Flash (ICSP) | Flash (ICSP) | ||
| Program Memory Size | 16 KB (8K x 16) | 16 KB | 16 KB | 16 KB | |||
| RAM | 768 bytes | 768 bytes | 768 bytes | 768 bytes | |||
| Max Clock Frequency | 40 MHz (10 MIPS) | 40 MHz | 40 MHz | 40 MHz | |||
| ADC | 5-channel, 8-bit | 5-channel, 8-bit | 5-channel, 10-bit | 10-channel, 10-bit | |||
| Lifecycle Status | Obsolete | Obsolete | Active | Active | |||
| RoHS Compliance | Non-compliant (CerDIP package) | Compliant (plastic) | Compliant (plastic) |
Key Differentiators
- Windowed ceramic package for UV erasure and re-programming (vs PIC18C242-I/P)
- Field-replaceable and socket-friendly for legacy industrial sustainment (vs PIC18F242-I/SP)
- Same silicon die as PIC18C family for code reuse (vs PIC18F2420-I/SP)
Design Notes
The PIC18C242/JW is obsolete and not recommended for new designs. Production runs should migrate to PIC18F242-I/SP or PIC18F2420-I/SP, which use flash memory and support in-circuit serial programming (ICSP). The windowed CerDIP package retains lead-bearing ceramic construction that fails RoHS requirements; lead-free designs must use plastic-packaged alternatives. Verify that the application does not rely on the PIC18C silicon errata documented in the device silicon errata sheet before reusing in legacy systems.
Insert the PIC18C242/JW in a 28-pin machine-pin socket (e.g., 3M Textool or Aries) on the PCB so the part can be removed for UV erasure. Place a 0.1uF decoupling capacitor directly between pin 27 (VDD) and pin 26 (VSS), with trace length under 5mm to suppress switching noise from the oscillator. Use a parallel 10uF tantalum or ceramic bulk capacitor near the VDD pins for transient load response, and route the OSC1/OSC2 traces short and surrounded by ground pour to minimize EMI pickup.
When migrating from PIC18C242/JW to PIC18F242, verify that CONFIG bits (oscillator, watchdog, brown-out, code protection) translate correctly between the EPROM and flash device. The PIC18F242's CONFIG register layout differs from PIC18C242; consult Microchip migration document DS30009693 or the device header file before reusing code. The flash part adds an internal RC oscillator, eliminating the external crystal in some applications. Also confirm that interrupt vector addresses remain unchanged between the two devices to avoid latent firmware bugs.
Compliance Information
PIC18C242/JW uses a pre-RoHS ceramic DIP package with lead-bearing brazing, so it is NOT RoHS compliant. The PIC18F242 in plastic SPDIP/SOIC is the RoHS-compliant replacement. AEC-Q100 qualification does not apply - for automotive, choose PIC18F242-I/SP with explicit automotive grade marking. REACH and conflict-mineral status not stated in the original datasheet; contact Microchip for current declarations.
