PIC18C242-I/SP - 8-Bit 40MHz 16KB OTP MCU | Microchip
MPN: PIC18C242-I/SP ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.22 | $8.22 |
| 10 | $7.45 | $74.50 |
| 100 | $6.62 | $662.00 |
| 500 | $5.91 | $2,955.00 |
| 1,000 | $5.27 | $5,270.00 |
PIC18C242-I/SP Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory, data memory, and peripherals such as timers, A/D converters, and communication interfaces onto one die. The PIC18 family is the high-performance tier of Microchip's 8-bit PIC architecture, offering an enhanced instruction set of 77 single-word instructions with C-friendly orthogonality, upward compatibility with PIC16 and PIC17 code, and hardware multipliers not present on the PIC16 baseline. PIC18C devices use OTP EPROM for program storage, making them one-time-programmable parts suitable for mature production runs, while PIC18F successors migrated to flash memory for in-system re-programmability.
Key features of the PIC18C242 include five 10-bit A/D converter input channels (the 28-pin members of the family have a reduced A/D channel count compared to the 40-pin PIC18C442/452), an Addressable USART (AUSART) for serial communications, a Master Synchronous Serial Port (MSSP) supporting SPI and I2C, multiple timers, and parallel I/O. The wide operating voltage range typically spans 2.0 V to 5.5 V, with the industrial (-I) temperature grade covering -40 C to +85 C.
Architecturally, the PIC18C242 uses a Harvard memory layout with separate program and data buses, a 16-bit instruction word, and a 31-level deep hardware stack. The OTP cell enables a robust monolithic CMOS process, but at the cost of non-volatility being physically locked after programming, which contrasts with flash-based PIC18F devices that can be re-programmed thousands of times.
Typical applications include industrial control nodes, motor control signal conditioning, instrumentation front-ends, and embedded sensor interfaces where a deterministic 8-bit core and simple peripheral mix are sufficient. Designers should consider PIC18F242, PIC18F2520, or PIC18F2525 as modern pin-compatible flash alternatives for new designs requiring in-field firmware updates.
When selecting this part, verify the OTP-only constraint of the PIC18C family against the production programming flow: once programmed, parts cannot be re-flashed, so engineering builds must be performed on the PIC18F equivalent during development. A 28-pin SPDIP footprint allows easy breadboard prototyping and through-hole assembly.
Drop-in alternatives for PIC18C242-I/SP — 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/SP (same form factor and footprint) — differing in Mounting Type, Package, A/D Converter, Operating Temperature Range, Serial Interfaces.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F242-I/SP
✅ Drop-In✓ In Stock
$5.3 / Unit
View Datasheet →PIC18C242-E/SP
✅ Drop-In✓ In Stock
$4.25 / Unit
View Datasheet →PIC18F252-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2520-I/SP
✅ Drop-In✓ In Stock
$3.33 / Unit
View Datasheet →PIC18C242-I/SP Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 (8-bit RISC) |
| Instruction Set | 77 single-word instructions |
| Maximum Clock Frequency | 40 MHz |
| Performance | 10 MIPS (100 ns instruction execution) |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 16 KB (8K x 16) |
| Data RAM | 512 bytes |
| Package | 28-pin SPDIP (0.300 inch, 7.62 mm) |
| Operating Voltage Range | 2.0 V to 5.5 V (typical, see datasheet for full range) |
| Operating Temperature Range | -40 C to +85 C (Industrial grade, -I) |
| A/D Converter | 10-bit, 5 channels (28-pin family reduced from 40-pin) |
| Serial Interfaces | AUSART, MSSP (SPI / I2C) |
| Parallel Slave Port (PSP) | Not implemented on 28-pin devices |
| Mounting Type | Through-Hole (SPDIP) |
| Recommended Modern Replacement | PIC18F242 (flash, pin-compatible) |
PIC18C242-I/SP Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (reset) input / programming voltage |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input channel 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input channel 1 |
| Pin 4 | RA2/AN2/VREF- — PORTA bit 2 / Analog input 2 / A/D negative reference |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input 3 / A/D positive reference |
| 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 | OSC2/CLKO — Oscillator output / clock output |
| Pin 9 | OSC1/CLKI — Oscillator input / clock input |
| 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 module |
| Pin 12 | RC2/CCP1 — PORTC bit 2 / CCP1 module (PWM/capture/compare) |
| 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 / AUSART transmit / AUSART clock |
| Pin 17 | RC7/RX/DT — PORTC bit 7 / AUSART receive / AUSART data |
| Pin 18 | VSS — Ground reference |
| Pin 19 | VDD — Positive power supply |
| 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 module |
| Pin 24 | RB4 — PORTB bit 4 |
| Pin 25 | RB5 — PORTB bit 5 |
| Pin 26 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 27 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 28 | VSS — Ground reference |
Typical Applications
PIC18C242-I/SP is suitable for 6 applications: Industrial Control Nodes, Motor Control Signal Conditioning, Instrumentation Front-Ends, Embedded Sensor Interfaces, Legacy Automotive Body Controllers, Educational and Hobbyist Projects.
Industrial Control Nodes
The PIC18C242-I/SP fits industrial control nodes because its 8-bit PIC18 core provides deterministic 100 ns instruction execution at 40 MHz, ideal for tight control loops in PLC-style I/O modules. Its 16 KB OTP program memory holds typical ladder-logic replacement firmware plus serial protocol stacks, while the 10-bit A/D converter with 5 channels digitizes 4-20 mA sensor inputs directly. The AUSART enables Modbus RTU communication to a host PLC, and the MSSP supports SPI to local digital sensors. Industrial temperature grade (-40 C to +85 C) tolerates factory floor environments, and the 28-pin SPDIP through-hole package withstands vibration better than SMD alternatives in chassis-mounted equipment.
Recommended
Motor Control Signal Conditioning
For motor control signal conditioning, the PIC18C242-I/SP provides the deterministic timing needed to sample current shunt signals and back-EMF zero-crossing detectors. Its 10-bit A/D converter with 5 input channels captures phase currents and DC bus voltage at the 40 MHz system clock rate, while the MSSP SPI channel drives external DAC chips for motor reference generation. The 16 KB OTP program memory holds sensorless BLDC or stepper control state machines, and the 512 B RAM supports real-time commutation tables. Industrial temperature operation ensures reliability near motor drive heatsinks. For modern designs with field-update requirements, PIC18F242 or PIC18F2520 are pin-compatible flash equivalents.
Recommended
Instrumentation Front-Ends
The PIC18C242-I/SP is well suited for instrumentation front-end controllers, where its 10-bit A/D converter digitizes analog sensor outputs and the AUSART streams measurement data to a host display or logger. The 40 MHz clock enables oversampling and software filtering of noisy transducer signals (thermocouples, load cells, pressure sensors), and the 16 KB OTP program memory holds calibration tables and linearization routines. Industrial temperature range supports laboratory and field instrumentation, while the 28-pin SPDIP package fits legacy through-hole instrument PCBs. The MSSP port connects to SPI LCD displays or I2C EEPROM for parameter storage.
Recommended
Embedded Sensor Interfaces
For embedded sensor interface hubs, the PIC18C242-I/SP aggregates data from multiple digital and analog sensors using its MSSP (SPI + I2C) and A/D converter. The PIC18 core's deterministic interrupt latency at 40 MHz guarantees timely sensor polling, while the AUSART forwards pre-processed data over RS-232/RS-485 to a central controller. With 512 B of data RAM, the device buffers burst sensor readings before transmitting, reducing host CPU load. Industrial temperature operation supports outdoor and industrial sensor deployments. Its OTP memory makes it cost-effective for high-volume sensor products that do not require firmware updates.
Recommended
Legacy Automotive Body Controllers
The PIC18C242-I/SP can serve in legacy automotive body controller modules (BCM) for non-safety functions such as interior lighting, accessory control, and switch input monitoring. The AUSART interfaces with body control networks, the MSSP drives SPI-controlled LED drivers or switch matrices, and the 10-bit A/D reads resistive switch inputs and battery voltage. However, automotive designs now require AEC-Q100 qualification, which PIC18C242 lacks, so the automotive-grade successor PIC18F242-I/SP or PIC18F2520-I/SP with Q1 suffixes is preferred. Industrial temperature grade fits cabin environments.
Recommended
Educational and Hobbyist Projects
The PIC18C242-I/SP is popular in educational settings and hobbyist projects because the 28-pin SPDIP package fits standard breadboards and through-hole perfboards, simplifying prototyping. The PIC18 instruction set with only 77 single-word instructions is approachable for students learning embedded programming, and the AUSART plus MSSP peripherals provide hands-on experience with serial protocols. Many legacy PIC18 development boards and PICDEM kits target this exact pinout. For new educational designs, however, the flash-based PIC18F242 or PIC18F46K22 is preferred, since OTP parts cannot be re-programmed after a programming mistake, slowing the learning cycle.
Recommended
Recommended Products Summary
Engineering reference data for PIC18C242-I/SP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F242-I/SP | PIC18C242-E/SP | PIC18F252-I/SP | PIC18F2520-I/SP |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-pin SPDIP (0.300 inch) | 28-pin SPDIP - same | 28-pin SPDIP - same | 28-pin SPDIP - same | 28-pin SPDIP - same |
| Program Memory | 16 KB OTP | 16 KB Flash | 16 KB OTP | 32 KB Flash | 32 KB Flash |
| Data RAM | 512 B | 512 B | 512 B | 1.5 KB | 1.5 KB |
| Maximum Clock | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) |
| Operating Temperature | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) | -40 C to +125 C (Extended) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) |
| A/D Converter | 10-bit, 5 channels | 10-bit, 5 channels | 10-bit, 5 channels | 10-bit, 5 channels | 10-bit, 10 channels |
| Reprogrammability | No (OTP only) | Yes (Flash, ~1000 cycles) | No (OTP only) | Yes (Flash, ~1000 cycles) | Yes (Flash, ~1000 cycles) |
| Lifecycle Status | Obsolete | Active | Obsolete | Active | Active |
| Unit Price (qty 1) | $8.22 (residual stock) | Lower (active production) | Similar (residual stock) | Lower (active production) | Lower (active production) |
Key Differentiators
- Officially recommended flash replacement available with identical pinout (vs PIC18F242-I/SP)
- Extended temperature variant available for higher operating ranges (vs PIC18C242-E/SP)
- Higher-memory flash upgrade path within same footprint (vs PIC18F2520-I/SP)
- Surface-mount flash alternative for compact designs (vs PIC18F242-I/SO)
Design Notes
The PIC18C242 uses OTP EPROM program memory, which cannot be erased or re-programmed after the first write. Programming mistakes during development brick the part, so engineers should prototype on a flash-based PIC18F242-I/SP and only switch to PIC18C242 for production builds. Use a dedicated programming fixture and verify firmware on PIC18F242 hardware before committing OTP parts. The Microchip MPLAB environment supports both PIC18C and PIC18F parts with the same toolchain.
Power supply decoupling for PIC18C242 requires a 0.1 uF ceramic capacitor placed as close as possible to the VDD pin (pin 20), with a 10 uF bulk capacitor on the same node to handle switching transients. The PIC18C242 has two VSS pins (pins 18 and 28) that must both be connected to ground for proper I/O drive symmetry. For A/D converter accuracy, the VREF+ and VREF- pins (RA3/RA2) require additional 0.1 uF bypass capacitors even when using the internal VDD-based reference, especially in noisy motor control environments.
The 28-pin SPDIP package provides generous pin spacing (2.54 mm pitch) that simplifies through-hole PCB layout, but engineers should still reserve a ground plane under the device to reduce EMI susceptibility. Place the crystal (filter or resonator) within 1 cm of the OSC1/OSC2 pins (pins 8 and 9) to minimize parasitic capacitance, and route MCLR (pin 1) with a 10 kohm pull-up to VDD and a 0.1 uF cap to ground for proper reset behavior. ISP programming via PGC (RB6) and PGD (RB7) requires 4.7 kohm series resistors on long programming cables.
The AUSART pins (RC6/TX and RC7/RX) should be routed away from the oscillator traces to prevent coupling of clock noise into the serial data path. For RS-232 levels, place a MAX232 or equivalent transceiver within 5 cm of the AUSART pins, and add a 100 ohm series resistor on each AUSART line for EMI suppression. The MSSP SPI signals (SCK, SDO, SDI, SS) require matched trace lengths if the SPI bus runs above 5 MHz; otherwise standard length-matching within 2 cm is sufficient for the 40 MHz system clock.
Compliance Information
PIC18C242-I/SP is a legacy OTP part from Microchip's PIC18C family, predating widespread RoHS adoption. RoHS/REACH compliance status was not confirmed in the verified web data and is marked unknown. The part is not AEC-Q100 qualified; automotive designers should choose PIC18F242-I/SP with automotive-grade Q1 suffix variants.
