PIC18F4550T-I/ML - 8-bit USB MCU, 32KB Flash, 48MHz, 44-QFN | Microchip
MPN: PIC18F4550T-I/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.85 | $7.85 |
| 10 | $7.1 | $71.00 |
| 100 | $6.3 | $630.00 |
| 500 | $5.65 | $2,825.00 |
| 1,000 | $5.1 | $5,100.00 |
PIC18F4550T-I/ML Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, data memory, I/O peripherals and often communication interfaces into one package. The PIC18 family uses an 8-bit RISC Harvard architecture with a 16-bit instruction word, optimized for deterministic real-time control. USB-capable PIC18 devices such as the PIC18F4550 sit at the intersection of general-purpose embedded control and host-connected peripherals, eliminating the need for an external USB interface chip.
Key features include a Full-Speed (12 Mbit/s) USB 2.0 device transceiver on-chip, three serial ports (USB, I2C/SPI up to 10 Mbit/s, and an LIN-capable EUSART), 35 digital I/O pins, a 10-bit ADC with up to 13 channels, two analog comparators, four timer modules and the nanoWatt power-managed sleep/Run/Idle/PRI_RUN modes. The enhanced Flash supports >100k erase/write cycles and >40-year retention, with self-programmability for in-field firmware updates.
The architecture combines the standard PIC18 peripheral set with a hardened USB SIE, internal oscillator calibration, and CTMU for capacitive touch sensing. The 44-QFN exposed pad lowers theta-JA for better thermal dissipation in compact consumer and industrial designs.
Typical applications include USB HID peripherals (keyboards, mice, custom input devices), USB-to-UART bridges, data loggers with PC connectivity, industrial sensor nodes with USB diagnostic ports, and educational/hobbyist development platforms. The combination of USB, ADC, PWM and timers makes the PIC18F4550 a flexible general-purpose MCU for any product that needs a direct PC connection.
When designing with this part, observe the QFN ground/thermal pad soldering guidelines (land pattern, paste stencil, reflow profile) and place the VUSB decoupling capacitor as close to the VUSB pin as possible. For bus-powered USB designs, ensure the total current budget stays below 100 mA before enumeration or implement the proper power-switching logic.
This page synthesizes distributor pricing, same-package drop-in alternatives and practical design notes not found in the manufacturer datasheet alone, helping procurement and embedded engineers qualify the part faster.
Drop-in alternatives for PIC18F4550T-I/ML — 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 PIC18F4550T-I/ML (same form factor and footprint) — differing in Core Architecture, Package, Program Memory (Flash), Timers, USB Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F4550-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4455T-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2550T-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F46K22T-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4458T-I/ML
✅ Drop-In✓ In Stock
$4.25 / Unit
View Datasheet →PIC18F4520-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4550T-I/ML Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18, 8-bit RISC Harvard |
| Instruction Word Width | 16-bit |
| Program Memory (Flash) | 32 KB (16K x 16) |
| RAM | 2 KB (2048 bytes) |
| EEPROM | 256 bytes |
| Maximum CPU Clock | 48 MHz (12 MIPS) |
| Supply Voltage (Vdd) | 2.0 V to 5.5 V |
| Operating Temperature | -40 C to +85 C (Industrial) |
| I/O Pins | 35 |
| ADC | 10-bit, up to 13 channels |
| USB Interface | USB 2.0 Full-Speed (12 Mbit/s) device, on-chip transceiver |
| Other Serial Interfaces | 1x I2C/SPI (up to 10 Mbit/s), 1x EUSART (LIN-capable) |
| Timers | 4 (Timer0/1/2/3) |
| Analog Comparators | 2 |
| PWM Channels | Up to 5 (10-bit CCP/ECCP) |
| Package | 44-pin QFN with exposed pad (8x8 mm) |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel |
| RoHS Status | Compliant |
| MSL Level | 3 (per JEDEC J-STD-020) |
PIC18F4550T-I/ML Pin Configuration
| Pin 1 | RA0/AN0 — PORTA bit 0 / analog input channel 0 |
| Pin 2 | RA1/AN1 — PORTA bit 1 / analog input channel 1 |
| Pin 3 | RA2/AN2/VREF- — PORTA bit 2 / analog input channel 2 / ADC negative reference |
| Pin 4 | RA3/AN3/VREF+ — PORTA bit 3 / analog input channel 3 / ADC positive reference |
| Pin 5 | RA4/T0CKI/C1OUT — PORTA bit 4 / Timer0 clock input / comparator 1 output |
| Pin 6 | RA5/AN4/SS/HLVDIN/C2OUT — PORTA bit 5 / analog input channel 4 / SPI slave select / HLVD input / comparator 2 output |
| Pin 7 | RE0/RD — PORTE bit 0 / parallel-port read control |
| Pin 8 | RE1/WR — PORTE bit 1 / parallel-port write control |
| Pin 9 | RE2/CS — PORTE bit 2 / parallel-port chip-select |
| Pin 10 | VDD — Positive supply voltage (2.0V to 5.5V) |
| Pin 11 | VSS — Ground reference |
| Pin 12 | OSC1/CLKI/RA7 — Oscillator crystal input / external clock input / PORTA bit 7 |
| Pin 13 | OSC2/CLKO/RA6 — Oscillator crystal output / clock output / PORTA bit 6 |
| Pin 14 | RC0/T1OSO/T13CKI — PORTC bit 0 / Timer1 oscillator output / Timer1/Timer3 clock input |
| Pin 15 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / Capture-Compare-PWM 2 |
| Pin 16 | RC2/CCP1 — PORTC bit 2 / Capture-Compare-PWM 1 |
| Pin 17 | VUSB — USB internal transceiver 3.3V regulator output / external capacitor |
| Pin 18 | RC4/D-/VM — PORTC bit 4 / USB D- line / external USB transceiver VM input |
| Pin 19 | RC5/D+/VP — PORTC bit 5 / USB D+ line / external USB transceiver VP input |
| Pin 20 | RC6/TX/CK — PORTC bit 6 / EUSART TX / EUSART synchronous clock |
| Pin 21 | RC7/RX/DT — PORTC bit 7 / EUSART RX / EUSART synchronous data |
| Pin 22 | RB0/AN12/INT0 — PORTB bit 0 / analog input channel 12 / external interrupt 0 |
| Pin 23 | RB1/AN10/INT1 — PORTB bit 1 / analog input channel 10 / external interrupt 1 |
| Pin 24 | RB2/AN8/INT2/VMO — PORTB bit 2 / analog input channel 8 / external interrupt 2 / parallel-port VMO |
| Pin 25 | RB3/AN9/CCP2/VPO — PORTB bit 3 / analog input channel 9 / CCP2 / parallel-port VPO |
| Pin 26 | RB4/AN11/KBI0 — PORTB bit 4 / analog input channel 11 / interrupt-on-change bit 0 |
| Pin 27 | RB5/KBI1/PGM — PORTB bit 5 / interrupt-on-change bit 1 / LVP programming |
| Pin 28 | RB6/KBI2/PGC — PORTB bit 6 / interrupt-on-change bit 2 / ICSP clock |
| Pin 29 | RB7/KBI3/PGD — PORTB bit 7 / interrupt-on-change bit 3 / ICSP data |
| Pin 30 | VDD — Positive supply voltage (2.0V to 5.5V) |
| Pin 31 | VSS — Ground reference |
| Pin 32 | RD0/SPP0 — PORTD bit 0 / Streaming Parallel Port data bit 0 |
| Pin 33 | RD1/SPP1 — PORTD bit 1 / Streaming Parallel Port data bit 1 |
| Pin 34 | RD2/SPP2 — PORTD bit 2 / Streaming Parallel Port data bit 2 |
| Pin 35 | RD3/SPP3 — PORTD bit 3 / Streaming Parallel Port data bit 3 |
| Pin 36 | RC3/SPP4 — PORTC bit 3 / Streaming Parallel Port data bit 4 |
| Pin 37 | RD4/SPP5 — PORTD bit 4 / Streaming Parallel Port data bit 5 |
| Pin 38 | RD5/SPP6/P1B — PORTD bit 5 / Streaming Parallel Port data bit 6 / PWM 1 output B |
| Pin 39 | RD6/SPP7/P1C — PORTD bit 6 / Streaming Parallel Port data bit 7 / PWM 1 output C |
| Pin 40 | RD7/SPP8/P1D — PORTD bit 7 / Streaming Parallel Port data bit 8 / PWM 1 output D |
| Pin 41 | VSS — Ground reference |
| Pin 42 | VDD — Positive supply voltage (2.0V to 5.5V) |
| Pin 43 | AVSS — Analog ground reference |
| Pin 44 | AVDD — Analog positive supply voltage |
| Pin EP | Exposed Pad (GND) — Center thermal pad - must be soldered to ground for thermal dissipation and electrical reference |
Typical Applications
PIC18F4550T-I/ML is suitable for 7 applications: USB HID Peripherals (Keyboard, Mouse, Custom Input), USB-to-UART and USB-to-SPI Bridges, Industrial Sensor Nodes with USB Diagnostic Port, Educational / Hobbyist Development Boards, Data Loggers with PC Connectivity, Custom USB Audio Class Devices, Automotive LIN Bus Nodes (After-market).
USB HID Peripherals (Keyboard, Mouse, Custom Input)
The PIC18F4550T-I/ML is a benchmark part for USB HID-class peripherals thanks to its integrated Full-Speed USB 2.0 SIE and on-chip transceiver. The device achieves 12 Mbit/s USB throughput at the 48 MHz system clock, eliminating the need for an external USB PHY. With 35 I/O pins it can directly scan key matrices up to 8x8, drive LED indicators, and read mechanical or capacitive switches. The 32 KB Flash comfortably holds HID descriptors plus application logic, and the 2 KB RAM handles HID report buffers without dropping frames. PIC18F4550T-I/ML ships with Microchip's free USB stack, allowing designers to bring up HID firmware in days rather than weeks.
Recommended
USB-to-UART and USB-to-SPI Bridges
The PIC18F4550T-I/ML is commonly used as a USB-to-serial bridge IC, replacing legacy CP210x or FT232x designs with a reprogrammable Microchip MCU. The integrated EUSART provides UART up to 115.2 kbaud, and the MSSP port delivers SPI master/slave up to 10 Mbit/s per the Microchip datasheet. USB CDC firmware with the Microchip USB stack makes the device appear as a virtual COM port on Windows, macOS and Linux without additional drivers. The 44-QFN package and exposed pad enable small dongle form factors, and the industrial temperature range supports field-deployed instrumentation. Low-power Run/Idle modes from the nanoWatt feature set reduce idle consumption for bus-powered designs.
Recommended
Industrial Sensor Nodes with USB Diagnostic Port
For industrial sensor nodes, the PIC18F4550T-I/ML combines a 10-bit ADC (up to 13 channels), 4 timers, 2 comparators, PWM outputs, I2C and SPI in one chip, with a USB port for PC-based configuration and diagnostics. The 2.0V to 5.5V supply range supports battery and 24V-bus-derived rails, and the industrial -40 C to +85 C grade is rated for factory-floor deployments. Engineers can use USB to stream ADC readings to a laptop, perform in-field calibration, or update firmware via the self-programmable Flash. The 44-QFN exposed pad keeps junction temperature low even at 48 MHz full clock, supporting sealed IP65 enclosures without active cooling.
Recommended
Educational / Hobbyist Development Boards
The PIC18F4550T-I/ML is the MCU of choice for many educational boards (e.g. Pinguino, Open18F4550, Microchip PICDEM FS-USB) because it integrates USB and exposes all peripherals in a beginner-friendly QFN/TQFP package. Students can learn USB enumeration, ADC, PWM, timers and interrupt-driven firmware on one chip. The MPLAB X IDE and free XC8 compiler plus the Microchip USB stack form a zero-cost toolchain for universities and hobbyists. The PIC18F4550T-I/ML also serves as a controller for robotics and motor-control class projects, with PWM driving small DC motors and encoders read via timers and interrupts.
Recommended
Data Loggers with PC Connectivity
The PIC18F4550T-I/ML supports standalone data loggers that periodically sample sensors and then connect to a host PC for data offload via USB Mass Storage or CDC class. Its 32 KB Flash fits configuration tables and a small FAT12/16 file system, while the 2 KB RAM holds one sector buffer for writes. Real-time-clock updates and EEPROM-backed logging parameters enable unattended operation across weeks. With USB bus-power, the entire logger can be powered and read through a single cable, simplifying field deployment. The -40 C to +85 C industrial range suits environmental monitoring cabinets.
Recommended
Custom USB Audio Class Devices
Although primarily marketed for HID, the PIC18F4550T-I/ML can implement low-bandwidth USB Audio Class 1.0 devices such as USB headsets, microphones and tone generators using the on-chip SIE and a PWM-driven DAC. The MSSP peripheral handles I2S-to-USB bridging in software with DMA-style buffering, while the comparator plus PWM generate line-level analog output. With 32 KB Flash, the audio firmware plus descriptors fit comfortably, leaving cycles for user interface LEDs and buttons. Microchip's USB Audio class firmware examples shorten development time considerably.
Recommended
Automotive LIN Bus Nodes (After-market)
In non-safety automotive after-market applications (interior lighting, sensor clusters, gauges), the PIC18F4550T-I/ML's EUSART supports LIN 1.x/2.0 master and slave protocols with the on-chip auto-baud feature. Its industrial -40 C to +85 C range covers cabin environments, and the 44-QFN package plus exposed pad handles the 125 C automotive under-hood ambient with proper PCB layout. The integrated USB allows technicians to plug into a PC for parameter tuning, fault code readout or firmware update without a separate programmer. For OEM safety-critical applications, the AEC-Q100 qualified PIC18F4550T-I/ML must be substituted with the proper automotive part.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F4550T-I/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4550-I/ML | PIC18F4455T-I/ML | PIC18F46K22T-I/ML | PIC18F4458T-I/ML | PIC18F4520-I/ML |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-QFN (8x8 mm) with EP | 44-QFN (8x8 mm) with EP - same | 44-QFN (8x8 mm) with EP - same | 44-QFN (8x8 mm) with EP - same | 44-QFN (8x8 mm) with EP - same | 44-QFN (8x8 mm) with EP - same |
| Flash Program Memory | 32 KB | 32 KB | 24 KB | 64 KB | 24 KB | 32 KB |
| RAM | 2 KB | 2 KB | 2 KB | 4 KB | 2 KB | 1.5 KB |
| EEPROM | 256 B | 256 B | 256 B | 1024 B | 256 B | 256 B |
| Integrated USB 2.0 FS SIE | Yes (12 Mbit/s) | Yes | Yes | No | Yes | No |
| Maximum CPU Clock | 48 MHz (12 MIPS) | 48 MHz | 48 MHz | 64 MHz (16 MIPS) | 48 MHz | 40 MHz (10 MIPS) |
| Operating Voltage | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 1.8 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V |
| I/O Pins | 35 | 35 | 35 | 36 | 35 | 36 |
| Packaging Variant | Tape & Reel | Tray | Tape & Reel | Tape & Reel | Tape & Reel | Tray |
Key Differentiators
- Integrated Full-Speed USB 2.0 SIE with on-chip transceiver (vs PIC18F4520-I/ML)
- Industrial -40 C to +85 C temperature grade in 44-QFN (vs PIC18F2550T-I/ML)
- Free Microchip USB stack and class drivers (vs PIC18F46K22T-I/ML)
- 35 I/O plus Streaming Parallel Port for offload (vs PIC18F4455T-I/ML)
Design Notes
Estimated: the 44-QFN exposed pad on the PIC18F4550T-I/ML must be soldered to a continuous ground copper pour on the top and bottom PCB layers via thermal vias to achieve the rated thermal performance. With a 48 MHz CPU at full activity and active USB transactions, internal dissipation stays well below 0.5 W; however, continuous 48 MHz operation in a sealed enclosure with elevated ambient may still cause junction temperature rise. Provide at least 200 mm^2 of top-side copper tied to the EP and stitch with 4-8 thermal vias to the inner/ground plane for robust heat extraction per Microchip QFN PCB layout guidelines.
USB signal integrity is critical: place the 0.01 uF VUSB decoupling capacitor as close as physically possible to pin 17 (VUSB) and route the D+/D- lines (pins 18/19) as a 90-ohm differential pair with matched length and continuous ground reference. Keep the D+/D- trace length under 50 mm to comply with Full-Speed USB signal rise-time limits. Place the 1.5 kohm pull-up resistor on D+ near the MCU for full-speed device indication, and add ESD protection (such as USBLC6-2SC6) close to the connector to meet IEC 61000-4-2 air-discharge ratings.
Common PIC18F4550T-I/ML design pitfalls: (1) Failing to configure CONFIG1L for the correct oscillator mode - use HS or HS_PLL with a 20 MHz crystal for 48 MHz USB operation, not XT; (2) Forgetting to enable the USB module (UCON) and configure TRISC bits for RC4/RC5 before enumeration; (3) Skipping the VUSB capacitor, which causes USB enumeration failures; (4) Drawing >100 mA from VBUS in self-powered configurations without enabling USB power-switching logic, which violates USB spec; (5) Using internal RC oscillator for USB, which violates the +/- 0.25% clock-accuracy requirement - always use crystal for USB designs.
For bus-powered USB designs, VBUS supplies the 5V input to a 3.3V LDO (e.g. MCP1700) that powers VDD; the internal VUSB regulator (pin 17) provides the 3.3V USB reference. If the application uses a 3.3V-only supply, tie VUSB directly to VDD with a 0.01 uF capacitor. Disable the on-chip regulator (CONFIG2L.VREGEN) when supplying VUSB externally. In sleep mode the nanoWatt feature drops current to <1 uA, but the USB SIE cannot wake the device from deep sleep on its own - use USB-attached interrupt on RB0 or enable the ACTIVE-INTERRUPT-ON-IO feature if bus-powered wake is required.
Compliance Information
RoHS compliant per Microchip product page. AEC-Q100 qualification not available - select AEC-Q100-qualified PIC18F variants for automotive OEM safety applications. Lead-free and halogen-free per Microchip material declarations.
