PIC18LF242-I/SP - 8-Bit 40MHz PIC18 MCU 16KB Flash 28-SPDIP | Microchip
MPN: PIC18LF242-I/SP ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.62 | $4.62 |
| 10 | $4.07 | $40.70 |
| 100 | $3.55 | $355.00 |
| 500 | $3.1 | $1,550.00 |
| 1,000 | $2.75 | $2,750.00 |
PIC18LF242-I/SP Overview
An 8-bit microcontroller (MCU) is a single-chip computer built around an 8-bit data path, integrating a CPU, program memory (FLASH or ROM), data memory (RAM), EEPROM, peripherals, and interrupt logic on one die. The PIC18 family sits in Microchip's mid-range 8-bit hierarchy: PIC10/12/16/18 -> 8-bit MCU -> microcontroller -> embedded controller. PIC18 parts add a linear program-memory map, hardware multiplier, C-friendly architecture, and prioritized interrupts that the smaller PIC16 cores lack, making them the workhorse for cost-sensitive 8-bit designs that need real peripherals like CAN, USB, or Enhanced USART.
Key features include a 10-bit ADC (5 channels on this 28-pin part), 1 capture/compare/PWM module, 1 Enhanced USART, MSSP for SPI/I2C, two 8-bit timers plus three 16-bit timers, and a programmable Watchdog Timer with its own on-chip RC oscillator. The FLASH program memory is in-circuit serial programmable through ICSP, and the device supports ICD2/ICD3 real-time in-circuit debugging with two I/O pins dedicated to that purpose. With four oscillator modes including a 31 kHz LP mode and an 8x software PLL, the LF242 is tailored for low-power and crystal-stabilized timing.
The PIC18LF242-I/SP is fabricated on Microchip's CMOS FLASH process with low-power enhancements versus the PIC18F242, including extended supply range down to 2.0 V (PIC18F242 bottom is 4.2 V). This makes the LF part the correct choice when the rail is sourced from a Li-ion cell, a 3.3 V LDO, or a regulated 2.5 V analog domain, while the F part is the more cost-effective pick for 5 V-only industrial boards.
Typical applications include industrial control panels, low-power instrumentation, sensor signal conditioning, motor control front-ends, and battery-backed security or HVAC peripherals. In each case the PIC18LF242 supplies 5-V-style peripherals from a 3.3 V rail while leaving enough MIPS for state-machine glue logic and a simple RTOS loop.
When designing with this device, ensure the supply decoupling follows Microchip's PIC18 LF family reference: one 100 nF ceramic at VDD and one bulk (>=10 uF tantalum or 47 uF aluminum) at the board's power entry. Reserve pins RB6 and RB7 for ICSP clock/data; adding series resistors or a buffer on these pins will block in-circuit programming and debugging.
This page combines distributor pricing, parametric comparison with same-family parts, and 28-SPDIP-compatible drop-in alternatives that are not always visible on the official PIC18 datasheet.
Drop-in alternatives for PIC18LF242-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 PIC18LF242-I/SP (same form factor and footprint) — differing in Package, Timers, Communication, Core Architecture, Program Memory (Flash).
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F242-I/SP
✅ Drop-In✓ In Stock
$5.3 / Unit
View Datasheet →PIC18LF252-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF242-E/SP
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18F252-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F242-E/SP
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18LF2320-I/SP
✅ Drop-In✓ In Stock
$4.78 / Unit
View Datasheet →PIC18LF242-I/SP Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 8-bit RISC |
| Program Memory | 16 KB (8K x 16) FLASH |
| Data RAM | 768 bytes |
| Data EEPROM | 256 bytes |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Supply Voltage (LF) | 2.0 V to 5.5 V |
| I/O Pins | 23 |
| ADC | 10-bit, 5 channels |
| Timers | 2x 8-bit + 3x 16-bit |
| Communication | 1x EUSART, 1x MSSP (SPI / I2C), 1x CCP |
| Package | 28-pin SPDIP (Skinny Plastic DIP) |
| Mounting Type | Through-Hole |
| Operating Temperature (Industrial) | -40 C to +85 C |
| In-Circuit Programming | ICSP (RB6/RB7) |
| In-Circuit Debug | ICD2/ICD3 compatible |
| Oscillator Modes | LP, XT, HS, RC (4 modes) |
| Watchdog Timer | Yes (with dedicated on-chip RC) |
| RoHS Status | Compliant |
PIC18LF242-I/SP Pin Configuration
| Pin 1 | /MCLR — Master Clear (reset) input, active low |
| Pin 2 | RA0/AN0 — Port A bit 0 / analog input 0 |
| Pin 3 | RA1/AN1 — Port A bit 1 / analog input 1 |
| Pin 4 | RA2/AN2/VREF- — Port A bit 2 / analog input 2 / ADC VREF- |
| Pin 5 | RA3/AN3/VREF+ — Port A bit 3 / analog input 3 / ADC VREF+ |
| Pin 6 | RA4/T0CKI — Port A bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — Port A bit 5 / analog input 4 / SPI slave select |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKI — Crystal oscillator input / external clock input |
| Pin 10 | OSC2/CLKO — Crystal oscillator output / clock output |
| Pin 11 | RC0/T1OSO/T1CKI — Port C bit 0 / Timer1 oscillator output / Timer1 clock |
| Pin 12 | RC1/T1OSI/CCP2 — Port C bit 1 / Timer1 oscillator input / CCP2 |
| Pin 13 | RC2/CCP1 — Port C bit 2 / Capture/Compare/PWM 1 |
| Pin 14 | RC3/SCK/SCL — Port C bit 3 / SPI clock / I2C clock |
| Pin 15 | RC4/SDI/SDA — Port C bit 4 / SPI data in / I2C data |
| Pin 16 | RC5/SDO — Port C bit 5 / SPI data out |
| Pin 17 | RC6/TX/CK — Port C bit 6 / EUSART TX / clock |
| Pin 18 | RC7/RX/DT — Port C bit 7 / EUSART RX / data |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply (2.0 V to 5.5 V) |
| Pin 21 | RB0/INT0 — Port B bit 0 / external interrupt 0 |
| Pin 22 | RB1/INT1 — Port B bit 1 / external interrupt 1 |
| Pin 23 | RB2/INT2 — Port B bit 2 / external interrupt 2 |
| Pin 24 | RB3/INT3 — Port B bit 3 / external interrupt 3 |
| Pin 25 | RB4 — Port B bit 4 |
| Pin 26 | RB5 — Port B bit 5 |
| Pin 27 | RB6/PGC — Port B bit 6 / ICSP clock (programming/debug) |
| Pin 28 | RB7/PGD — Port B bit 7 / ICSP data (programming/debug) |
Typical Applications
PIC18LF242-I/SP is suitable for 6 applications: Industrial Control Panels, Battery-Backed Sensor Instrumentation, HVAC and Building Automation Peripherals, Low-Cost Motor Control Front-Ends, Security and Access-Control Panels, User Interface and HMI Front-Ends.
Industrial Control Panels
The PIC18LF242-I/SP fits industrial control panels that need a rugged 8-bit MCU running from a regulated 24 V or 12 V rail stepped down to 3.3 V or 5 V. With 23 I/O, 16 KB FLASH and the PIC18 instruction set the part handles keypad scanning, LED multiplexing, relay drivers and Modbus RTU over the EUSART. The 2.0 V minimum supply lets designers share the rail with analog sensor conditioning blocks, while 768 bytes of RAM is enough for a Modbus frame plus a small protocol stack.
Recommended
Battery-Backed Sensor Instrumentation
Low-power sensor nodes benefit from the PIC18LF242-I/SP's 2.0 V minimum supply, which lets the MCU run directly from two AA cells or a single Li-ion cell without a boost converter. The 10-bit ADC with 5 channels handles thermistor, RTD bridge or strain-gauge signal conditioning, and the EUSART streams data to a remote logger at 9600-115200 baud. Sleep current stays in the microamp range when the CPU is idle and the watchdog timer can wake the part periodically.
Recommended
HVAC and Building Automation Peripherals
In HVAC and building automation the PIC18LF242-I/SP serves as the local I/O controller for thermostats, damper actuators and air-quality sensors. The 16 KB FLASH holds the scheduling firmware and a small Modbus or BACnet MS/TP slave stack, while the 5-channel ADC reads temperature, humidity and pressure. 23 digital I/O drive triac interfaces, opto-isolated relay outputs and character LCDs. The 28-SPDIP package remains popular for hand-soldered prototyping and field service.
Recommended
Low-Cost Motor Control Front-Ends
The PIC18LF242-I/SP works as the front-end controller for small brushed DC and stepper motor drives in appliances and small industrial machines. The 10-bit ADC samples back-EMF or current-sense signals while the CCP module generates PWM at up to 40 MHz. PIC18 cores execute a single-cycle hardware multiply so PI loop closure fits inside 10 MIPS. The 28-SPDIP package is friendly to through-hole prototyping boards used by motor-control labs.
Recommended
Security and Access-Control Panels
Security alarm panels and access controllers use the PIC18LF242-I/SP to manage keypad inputs, door-strike relays, siren drivers and a UART link to a central panel or modem. The FLASH memory stores event logs and zone configuration, and the EEPROM stores installer settings that must survive power loss. The 2.0 V minimum supply supports battery-backed operation through AC mains failures. In-circuit serial programming over RB6/RB7 lets installers re-flash firmware in the field.
Recommended
User Interface and HMI Front-Ends
The PIC18LF242-I/SP serves as the HMI controller in small appliances, lab instruments and vending machines, driving character LCDs, matrix keypads, LED status indicators and piezo buzzers. The MSSP peripheral handles SPI displays or I2C GPIO expanders, while the EUSART manages the link to a host processor. 23 digital I/O is sufficient for a 4x4 keypad plus 8 LEDs plus 8 dedicated control lines, leaving headroom for a rotary encoder input.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF242-I/SP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F242-I/SP | PIC18LF252-I/SP | PIC18F252-I/SP | PIC18LF242-E/SP | PIC18F242-E/SP | PIC18LF2320-I/SP |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SPDIP | 28-SPDIP - same | 28-SPDIP - same | 28-SPDIP - same | 28-SPDIP - same | 28-SPDIP - same | 28-SPDIP - same |
| Program Memory (FLASH) | 16 KB | 16 KB | 32 KB | 32 KB | 16 KB | 16 KB | 8 KB |
| Data RAM | 768 bytes | 768 bytes | 1536 bytes | 1536 bytes | 768 bytes | 768 bytes | 512 bytes |
| Supply Voltage (min) | 2.0 V | 4.2 V | 2.0 V | 4.2 V | 2.0 V | 4.2 V | 2.0 V |
| Max Clock Frequency | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) |
| I/O Pins | 23 | 23 | 23 | 23 | 23 | 23 | 23 |
| ADC Channels | 5 | 5 | 8 | 8 | 5 | 5 | 5 |
| Operating Temperature | -40 C to +85 C (I grade) | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +125 C (E grade) | -40 C to +125 C (E grade) | -40 C to +85 C |
Key Differentiators
- Low-voltage operation down to 2.0 V, broader than the F-variant (vs PIC18F242-I/SP)
- Industrial temperature grade -40 C to +85 C with the I-suffix (vs PIC18LF242-E/SP)
- 16 KB FLASH with 23 I/O in 28-SPDIP vs larger memory 28-SPDIP upgrade paths (vs PIC18LF252-I/SP)
Design Notes
Place a 100 nF ceramic decoupling capacitor directly across VDD (pin 20) and VSS (pin 19) within 5 mm of the package, plus a bulk capacitor of at least 10 uF at the board's power entry. The PIC18LF242 draws brief inrush currents up to 10-15 mA during FLASH programming; weak decoupling on the LF rail can cause VDD droop below 2.0 V and trigger brown-out resets mid-programming. Microchip's PIC18 reference manual section 2 recommends separating analog AVSS/AVDD pairs from digital VDD/VSS even on single-supply 28-pin parts.
Reserve pins RB6 (PGC, pin 27) and RB7 (PGD, pin 28) for ICSP programming and ICD2/ICD3 in-circuit debugging. Do not place series resistors, LEDs, or buffer drivers on these pins because they block the ICSP handshake with the programmer. For board layouts where RB6/RB7 are also used as user I/O, Microchip recommends tying them to the rest of the application through high-impedance paths (>=10 kohm) and ensuring no capacitor larger than 30 pF sits on the PGD line.
Do not confuse the PIC18LF242 with the PIC18F242: the LF part works from 2.0 V minimum while the F part requires at least 4.2 V. Dropping the F variant into a 3.3 V design will brown out at startup. Also verify the CONFIG fuses (oscillator, watchdog, brown-out voltage, low-voltage programming) match the supply rail; the LF part's BOR and LVP thresholds differ from the F part and must be set explicitly in the source configuration words.
When using the MSSP in SPI master mode at 40 MHz CPU clock, the maximum reliable SPI clock is 10 MHz. Place a 33 ohm series resistor close to the SCK (RC3) pin when driving long PCB traces or external displays to dampen ringing. For I2C bus pull-ups, 4.7 kohm is appropriate for 3.3 V and 100-400 kHz Standard/Fast mode; switch to 2.2 kohm for 1.7 kohm when adding more slaves or running Fast-mode Plus at 1 MHz.
Compliance Information
RoHS compliant per Microchip product page; REACH SVHC statement available from Microchip. Not AEC-Q100 qualified - for automotive designs use the PIC18F or PIC18LF K-series AEC-Q100 parts instead.
