PIC18LF2550-I/SP - 8-bit 48MHz 32KB Flash USB MCU | Microchip
MPN: PIC18LF2550-I/SP ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.2 | $7.20 |
| 10 | $6.55 | $65.50 |
| 100 | $5.78 | $578.00 |
| 500 | $5.1 | $2,550.00 |
| 1,000 | $4.55 | $4,550.00 |
PIC18LF2550-I/SP Overview
An 8-bit PIC microcontroller is a single-chip computer built on Microchip's RISC (Reduced Instruction Set Computer) Harvard architecture. Within the broader taxonomy it sits as: microcontroller -> embedded controller -> MCU -> 8-bit MCU -> PIC18 family. The 'LF' prefix denotes the low-voltage F-variant core that operates from 2.0V to 5.5V across industrial temperature ranges, while the 'F2550' part number identifies a member of the PIC18F2x50 sub-family characterized by on-chip Full-Speed USB. Devices in this family are widely used as cost-effective embedded controllers in consumer, industrial, and hobbyist designs.
Key features of the PIC18LF2550-I/SP include a 10-bit ADC with up to 10 input channels, a USART with LIN master/slave support, an MSSP peripheral configurable for SPI (up to 10 Mbit/s) or I2C (master/slave), 25 mA source/sink capability on I/O pins for direct LED drive, an internal 31 kHz to 8 MHz oscillator with PLL, nanoWatt power management, and ICD (In-Circuit Debug) support through two dedicated pins. The integrated USB 2.0 Full-Speed transceiver (12 Mbit/s) eliminates the need for an external PHY, a major advantage for HID, CDC, and custom-USB designs.
The PIC18LF2550-I/SP uses an enhanced PIC18 Harvard core with 16-bit-wide instructions, an 8-bit data path, hardware multiply, and a 32-level hardware stack. The CPU executes one instruction per 4 oscillator cycles, and the integrated PLL allows a 48 MHz system clock from a low-cost 4 MHz or 20 MHz external crystal, directly deriving the USB 48 MHz clock without an external oscillator.
Typical applications include USB human-interface devices (HID keyboards, mice, custom joysticks), USB-to-UART bridges (CDC class), low-cost logic analyzers and PICkit programmers, sensor data loggers with USB upload, industrial control panels with USB firmware update, and educational/hobbyist development boards such as the open-source PICKit2 demo board clones. Designers choose this part when they need a 5V-tolerant 8-bit MCU with on-chip USB in a through-hole DIP package that is easy to breadboard and hand-solder.
A key design consideration is that the USB D+ line requires a 1.5 kohm pull-up to 3.3V to signal Full-Speed connection; Microchip's datasheet recommends a software-controlled I/O pin driving this resistor so the host enumerates the device only when firmware is ready. Decoupling caps of 100 nF plus 4.7-10 uF bulk should be placed within 5 mm of VDD/VSS pins, and the VUSB pin must have a 220 nF plus 0.1 uF local bypass for the internal USB transceiver regulator.
This page synthesizes distributor pricing, drop-in PIC18F family alternatives, and practical design notes not found in the manufacturer datasheet alone, with cross-references to SPDIP-package PIC18F variants that pin-to-pin replace the PIC18LF2550-I/SP.
Drop-in alternatives for PIC18LF2550-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 PIC18LF2550-I/SP (same form factor and footprint) — differing in Timers, ADC, Package, Core Architecture, Mounting Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F2550-I/SP
✅ Drop-In✓ In Stock
$4.1 / Unit
View Datasheet →PIC18LF2455-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F24K50-I/SP
✅ Drop-In✓ In Stock
$2.42 / Unit
View Datasheet →PIC18LF2458-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF2550-I/SP Maximum Ratings & Electrical Characteristics
| Product Family | PIC18F USB Microcontrollers |
| Core Architecture | 8-bit PIC18 Harvard RISC |
| CPU Speed | 48 MHz (16 MIPS) |
| Program Memory (Flash) | 32 KB (16K x 16) |
| RAM | 2 KB |
| EEPROM | 256 bytes |
| Supply Voltage (VDD) | 2.0 V to 5.5 V |
| USB Transceiver | USB 2.0 Full-Speed (12 Mbit/s), on-chip |
| I/O Pins | 24 (digital I/O, multiplexed with analog) |
| ADC | 10-bit, up to 10 channels |
| Timers | 4 (Timer0, Timer1, Timer2, Timer3) |
| CCP/ECCP Modules | 1 CCP + 1 ECCP |
| Serial Interfaces | 1x USB FS, 1x EUSART (LIN), 1x MSSP (SPI up to 10 Mbit/s or I2C) |
| ICSP/ICD Debug | Yes (2-wire In-Circuit Debug) |
| Operating Temperature | -40C to +85C (Industrial) |
| Package | 28-pin SPDIP (Skinny Plastic DIP) |
| Mounting Type | Through-Hole (DIP) |
| RoHS Status | Compliant |
PIC18LF2550-I/SP Pin Configuration
| Pin 1 | MCLR/VPP/RE3 — Master Clear reset input / programming voltage / digital input-only RE3 |
| Pin 2 | RA0/AN0 — Digital I/O RA0 / analog input AN0 |
| Pin 3 | RA1/AN1 — Digital I/O RA1 / analog input AN1 |
| Pin 4 | RA2/AN2/VREF- — Digital I/O RA2 / analog input AN2 / ADC negative reference |
| Pin 5 | RA3/AN3/VREF+ — Digital I/O RA3 / analog input AN3 / ADC positive reference |
| Pin 6 | RA4/T0CKI — Digital I/O RA4 / Timer0 clock input (open-drain output) |
| Pin 7 | RA5/AN4/SS/HLVDIN — Digital I/O RA5 / analog input AN4 / SPI slave select / high/low voltage detect input |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKI — Crystal oscillator input / external clock input |
| Pin 10 | OSC2/CLKO — Crystal oscillator output / system clock output (FOSC/4) |
| Pin 11 | VDD — Positive supply voltage (2.0V to 5.5V) |
| Pin 12 | VSS — Ground reference |
| Pin 13 | RB0/AN12/INT0/FLT0 — Digital I/O RB0 / analog input AN12 / external interrupt 0 / ECCP fault input |
| Pin 14 | RB1/AN10/INT1 — Digital I/O RB1 / analog input AN10 / external interrupt 1 |
| Pin 15 | RB2/AN8/INT2 — Digital I/O RB2 / analog input AN8 / external interrupt 2 |
| Pin 16 | RB3/AN9/CCP2 — Digital I/O RB3 / analog input AN9 / Capture/Compare/PWM 2 output |
| Pin 17 | RB4/AN11/KBI0 — Digital I/O RB4 / analog input AN11 / interrupt-on-change KBI0 |
| Pin 18 | RB5/KBI1/PGM — Digital I/O RB5 / interrupt-on-change KBI1 / low-voltage ICSP programming |
| Pin 19 | RB6/PGC — Digital I/O RB6 / ICD clock (PGC) / in-circuit serial programming |
| Pin 20 | RB7/PGD — Digital I/O RB7 / ICD data (PGD) / in-circuit serial programming data |
| Pin 21 | RC0/T1OSO/T1CKI — Digital I/O RC0 / Timer1 oscillator output / Timer1 clock input |
| Pin 22 | RC1/T1OSI/CCP2 — Digital I/O RC1 / Timer1 oscillator input / Capture/Compare/PWM 2 |
| Pin 23 | RC2/CCP1 — Digital I/O RC2 / Capture/Compare/PWM 1 output |
| Pin 24 | RC3/SCK/SCL — Digital I/O RC3 / MSSP SPI clock / MSSP I2C clock |
| Pin 25 | RC4/D-/VMIO — Digital I/O RC4 / USB D- / VBUS MIO input-output |
| Pin 26 | RC5/D+/VP — Digital I/O RC5 / USB D+ / external USB transceiver input |
| Pin 27 | RC6/TX/CK — Digital I/O RC6 / EUSART TX / EUSART synchronous clock |
| Pin 28 | RC7/RX/DT/SDO — Digital I/O RC7 / EUSART RX / EUSART synchronous data / MSSP SPI data out |
Typical Applications
PIC18LF2550-I/SP is suitable for 6 applications: USB HID Custom Input Device, USB-to-UART Virtual COM Port (CDC Bridge), Low-Cost Logic Analyzer Probe, Industrial Sensor Data Logger with USB Upload, USB Firmware-Updatable Control Panel, Educational Microcontroller Development Board.
USB HID Custom Input Device
The PIC18LF2550-I/SP is well suited for USB HID-class input devices such as custom keyboards, mice, programmable keypads, and game controllers. The integrated USB 2.0 Full-Speed transceiver (12 Mbit/s) eliminates the need for an external PHY, while the 32 KB Flash holds a complete HID bootloader and report descriptors. The 2 KB SRAM supports HID report buffers and USB endpoint RAM (endpoint 0 plus up to 3 endpoints, 64 bytes each). Designers place the device on a USB-A pigtail board with a 1.5 kohm pull-up on D+ (RC4) driven by RC0, and use the on-chip USB voltage regulator on the VUSB pin with a 220 nF bypass cap.
Recommended
USB-to-UART Virtual COM Port (CDC Bridge)
The PIC18LF2550-I/SP is a classic CDC-class bridge that turns any USB host into a virtual COM port, replacing legacy RS-232 ports and FTDI cables. Its 48 MHz CPU executes the USB stack plus the EUSART-to-USB forwarding loop with ample margin. The LF voltage range (2.0V to 5.5V) lets it run from the 5V USB rail directly or from a 3.3V regulated rail if the downstream UART logic is 3.3V. Used in debug consoles for routers, point-of-sale terminals, and industrial sensors where RS-232 is being phased out but USB is the only available host port.
Recommended
Low-Cost Logic Analyzer Probe
Open-source logic analyzers such as the IRToy, Logic Pirate clones, and the Dangerous Prototypes USB IR Toy use the PIC18LF2550-I/SP as the sampling engine, leveraging its 48 MHz CPU clock to drive Timer1-based sampling at up to 24 MSPS in 4-channel mode. The 32 KB Flash holds the USB bulk-transfer firmware and 1 KB sample buffer while the 2 KB SRAM streams samples to the host PC over USB bulk endpoints. Designers connect four digital inputs to PORTB (RB0-RB3) and use the on-chip USB to deliver captured waveforms to Sigrok or PulseView client software running on the host.
Recommended
Industrial Sensor Data Logger with USB Upload
The PIC18LF2550-I/SP serves as an industrial-grade sensor data logger in factories and remote installations. The 10-bit ADC samples up to 10 analog channels (temperature, pressure, humidity, 4-20 mA loop inputs) at rates up to 100 kS/s aggregate, while the 32 KB Flash stores boot loader, USB stack, and a small FAT12/16 file system library for direct USB mass storage upload. The LF 2.0V to 5.5V range accepts power from industrial 24V buses stepped down by an external LDO, and the industrial -40C to +85C temperature range covers most factory environments.
Recommended
USB Firmware-Updatable Control Panel
Industrial control panels and HVAC thermostat front-ends use the PIC18LF2550-I/SP to enable field firmware upgrades over USB without opening the enclosure. The 32 KB Flash is partitioned into a USB HID bootloader (8 KB) plus application firmware (24 KB), and the bootloader uses the integrated USB FS transceiver to accept new firmware from a host PC. The 25 mA source/sink I/O capability directly drives LEDs, relay coils, and optocouplers without external drivers, while the ECCP module generates PWM for proportional valve or damper control.
Recommended
Educational Microcontroller Development Board
The PIC18LF2550-I/SP is a staple of university embedded-systems courses and hobbyist development boards (such as the open-source PICKit 2 demo board clones and the Microchip Low Pin Count USB Development Kit) because its 28-pin SPDIP package is easy to breadboard and hand-solder. The integrated USB eliminates the need for an external programmer once a USB bootloader is loaded, and the 32 KB Flash plus 2 KB RAM are large enough to teach USB enumeration, ADC sampling, PWM, I2C, SPI, and UART peripherals in a single semester course. Its nanoWatt power management modes are ideal for demonstrating sleep-current vs active-current trade-offs in battery-powered projects.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF2550-I/SP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F2550-I/SP | PIC18LF2455-I/SP | PIC18F24K50-I/SP | |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | |
| Package | 28-pin SPDIP | 28-pin SPDIP - same | 28-pin SPDIP - same | 28-pin SPDIP - same | 28-pin SPDIP - same |
| Program Flash | 32 KB | 32 KB (identical) | 24 KB (-25%) | 16 KB (-50%) | 24 KB (-25%) |
| RAM | 2 KB | 2 KB (identical) | 2 KB (identical) | 2 KB (identical) | 1 KB (-50%) |
| Operating Voltage | 2.0 V to 5.5 V | 4.2 V to 5.5 V | 2.0 V to 5.5 V (identical) | 2.7 V to 3.6 V | 2.0 V to 5.5 V (identical) |
| USB Transceiver | USB 2.0 FS, on-chip | USB 2.0 FS, on-chip (identical) | USB 2.0 FS, on-chip (identical) | USB 2.0 FS, on-chip (identical) | None (USB-less variant) |
| CPU Clock (max) | 48 MHz (16 MIPS) | 48 MHz (identical) | 48 MHz (identical) | 48 MHz (identical) | 48 MHz (identical) |
| ADC | 10-bit, 10 channels | 10-bit, 10 channels (identical) | 10-bit, 10 channels (identical) | 10-bit, 14 channels | 10-bit, 10 channels (identical) |
| SFR/Register Compatibility | PIC18F2550 family | Identical (F2550 family) | Identical (F2550 family) | Different (K50 family, firmware re-target) | Identical (F2550 family) |
Key Differentiators
- Only 32KB-Flash member of the F2550 family with 2.0V-5.5V LF voltage range in 28-pin SPDIP (vs PIC18F2550-I/SP)
- Pin-compatible with newer K50 USB family but with mature F2550 SFR mapping (vs PIC18F24K50-I/SP)
- Higher Flash than same-package LF2455 sibling (vs PIC18LF2455-I/SP)
Design Notes
The PIC18LF2550-I/SP operating voltage is 2.0V to 5.5V; when powered from the USB VBUS (5V), place a 100 nF decoupling cap within 5 mm of pins 11 (VDD) and 12 (VSS), and a 4.7 to 10 uF bulk cap near the same pair. The internal USB 3.3V regulator on the VUSB pin (pin 18 in 28-pin SPDIP) requires a 220 nF plus 0.1 uF local bypass; without this network the USB enumeration may fail intermittently. For battery-powered designs, the nanoWatt sleep modes (Sleep current down to 0.1 uA typical with watchdog disabled) require disabling the USB module and turning off all peripherals before entering Sleep.
Place the 4 MHz or 20 MHz crystal within 5 mm of pins 9 (OSC1) and 10 (OSC2) with short, equal-length traces and a ground guard ring to minimize EMI. The D+/D- traces (pins 25 and 26 in 28-pin SPDIP) must be routed as a 90-ohm differential pair with length matching within 150 mils, kept under 50 mm total length, and routed away from high-frequency switching nodes. Add a 1.5 kohm pull-up resistor on D+ (RC5) to 3.3V, driven by an I/O pin (typically RC0 or RC4) to allow software-controlled USB attach/detach.
Do not confuse the PIC18LF2550-I/SP (low-voltage, 2.0V to 5.5V) with the PIC18F2550-I/SP (4.2V to 5.5V only). At 3.3V supply the F-variant will fail to operate or behave erratically. Also, the configuration bits must be set for HS-PLL oscillator mode (HSPLL with 4x PLL from a 4 MHz crystal = 48 MHz) for USB operation; using HS without PLL yields only 20 MHz CPU clock and will not generate a valid USB 48 MHz clock, causing enumeration failure. Finally, the ECCP1 pin (RC2) outputs PWM at 25 mA source/sink, but driving a relay or motor directly will exceed the absolute maximum ratings; use a driver FET or opto-isolator.
Compliance Information
RoHS and REACH compliant per Microchip product page; industrial-grade -40C to +85C operating range; not AEC-Q100 qualified (consumer/industrial, not automotive). Lead-free SPDIP package is standard.
