PIC18LF4550T-I/ML - 8-Bit USB MCU, 32KB Flash, 44-QFN | Microchip
MPN: PIC18LF4550T-I/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.84 | $5.84 |
| 10 | $5.27 | $52.70 |
| 100 | $4.62 | $462.00 |
| 500 | $4.15 | $2,075.00 |
| 1,000 | $3.71 | $3,710.00 |
| 3,000 | $3.28 | $9,840.00 |
PIC18LF4550T-I/ML Overview
A PIC (Peripheral Interface Controller) microcontroller is a Harvard-architecture RISC device where program and data memory occupy separate buses, allowing simultaneous fetch and execute. The PIC18 family extends this concept to 16-bit wide instructions and 8-bit data paths with hardware multiply, position the family between 8-bit baseline/enhanced mid-range PICs and the 16-bit PIC24/dsPIC families. Within that hierarchy, the PIC18LF4550 is the highest-memory Full-Speed USB variant of the PIC18F2455/2550/4455/4550 family, distinguished from the 28-pin PIC18F2550 by its larger 40/44-pin package and 35 usable I/O lines.
Key features include on-chip Full-Speed USB 2.0 (12 Mbps) with internal transceiver, a 10-channel 10-bit ADC, two 8-bit and one 16-bit timers, two analog comparators, an EUSART with LIN support, MSSP for both I2C and SPI (up to 10 Mbps SPI), 13-channel hardware PWM (CCP/ECCP), and nanoWatt power management with multiple idle and sleep modes. The 44-VQFN EP package achieves a theta-JA of approximately 32 C/W on a 4-layer JEDEC test board, and the wide-voltage LF core makes the part attractive for both battery-powered and line-powered designs.
Architecturally, the PIC18LF4550 integrates the USB SIE, transceiver, and 3.3 V regulator internally, removing the need for external USB PHY components. The 32 KB Flash holds the USB stack, application code, and a small bootloader, while the 2 KB RAM accommodates USB endpoint buffers plus application variables. The internal oscillator block supports 8 MHz, 31 kHz, and PLL-derived 48 MHz modes, enabling USB operation without an external crystal.
Typical applications include Full-Speed USB peripherals such as HID input devices, CDC virtual COM ports, and custom device-class firmware; embedded data-acquisition and control nodes; industrial sensor interfaces; low-cost instrumentation; and consumer USB-charging controllers. The wide-voltage LF core makes the part particularly suited to portable USB battery-powered products.
When designing with this part, place the 44-VQFN exposed pad onto a continuous ground plane for thermal dissipation and signal integrity, ensure the VUSB pin decoupling includes 100 nF plus 4.7 uF bulk capacitance, and configure the internal 3.3 V USB regulator before bringing USB D+/D- online. Because the part supports ICSP via PGD/PGC, reserve those pins on the PCB for production programming access.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, including same-family 40-pin (PIC18LF4455) and 28-pin (PIC18LF2550) variants and Microchip cross-references to competitor parts.
Drop-in alternatives for PIC18LF4550T-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 PIC18LF4550T-I/ML (same form factor and footprint) — differing in Package, Core Architecture, ADC, Operating Temperature, Timers.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18LF4550-I/ML
✅ Drop-In✓ In Stock
$5.4 / Unit
View Datasheet →PIC18F4550T-I/ML
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →PIC18LF4550T-I/PT
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF4550T-I/ML Maximum Ratings & Electrical Characteristics
| Core | PIC 8-bit RISC |
| Series | PIC 18F |
| Program Memory | 32 KB (16K x 16) Flash |
| RAM | 2 KB (2K x 8) |
| Maximum CPU Frequency | 48 MHz |
| Supply Voltage Range | 2.0 V to 5.5 V (LF wide-voltage core) |
| Number of I/O Pins | 35 |
| USB Interface | USB 2.0 Full-Speed (12 Mbps), on-chip SIE + transceiver |
| ADC | 10-bit, 13 channels |
| Timers | 2 x 8-bit + 1 x 16-bit |
| Communication Interfaces | EUSART (LIN-capable), MSSP (I2C/SPI up to 10 Mbps), USB |
| PWM Channels | Up to 4 CCP + 1 ECCP (hardware PWM) |
| Comparators | 2 analog comparators |
| Package | 44-VQFN Exposed Pad (8x8 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40 C to +85 C (Industrial, 'I' suffix) |
| Packaging | Tape & Reel ('T' suffix) |
| RoHS Status | Compliant |
| Programming | ICSP (In-Circuit Serial Programming) |
PIC18LF4550T-I/ML Pin Configuration
| Pin 1 | RB2 — PORTB I/O bit 2 / analog input AN8 |
| Pin 2 | RB3 — PORTB I/O bit 3 / analog input AN9 |
| Pin 3 | RB4 — PORTB I/O bit 4 / analog input AN11 |
| Pin 4 | RB5 — PORTB I/O bit 5 / analog input AN13 / CCP3 |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB6 — PORTB I/O bit 6 / PGC (ICSP clock) |
| Pin 7 | RB7 — PORTB I/O bit 7 / PGD (ICSP data) |
| Pin 8 | VUSB — Internal 3.3 V USB regulator output (decouple with 4.7 uF + 100 nF) |
| Pin 9 | VDD — Positive supply (2.0-5.5 V for LF variant) |
| Pin 10 | RD0 — PORTD I/O bit 0 / PSP data |
| Pin 11 | RD1 — PORTD I/O bit 1 / PSP data |
| Pin 12 | RD2 — PORTD I/O bit 2 / PSP data |
| Pin 13 | RD3 — PORTD I/O bit 3 / PSP data |
| Pin 14 | RC4 — PORTC I/O bit 4 / D- (USB data minus) |
| Pin 15 | RC5 — PORTC I/O bit 5 / D+ (USB data plus) |
| Pin 16 | RC6 — PORTC I/O bit 6 / TX (EUSART async transmit) |
| Pin 17 | RC7 — PORTC I/O bit 7 / RX (EUSART async receive) |
| Pin 18 | VSS — Ground reference |
| Pin 19 | VDD — Positive supply |
| Pin 20 | RE3 — PORTE I/O bit 3 / MCLR (reset, active-low) |
| Pin 21 | RA0 — PORTA I/O bit 0 / AN0 |
| Pin 22 | RA1 — PORTA I/O bit 1 / AN1 |
| Pin 23 | RA2 — PORTA I/O bit 2 / AN2 / VREF- |
| Pin 24 | RA3 — PORTA I/O bit 3 / AN3 / VREF+ |
| Pin 25 | RA4 — PORTA I/O bit 4 / T0CKI |
| Pin 26 | RA5 — PORTA I/O bit 5 / AN4 / SS |
| Pin 27 | RE0 — PORTE I/O bit 0 / AN5 |
| Pin 28 | RE1 — PORTE I/O bit 1 / AN6 |
| Pin 29 | RE2 — PORTE I/O bit 2 / AN7 / CCP2 |
| Pin 30 | VDD — Positive supply |
| Pin 31 | VSS — Ground reference |
| Pin 32 | OSC1 — Crystal oscillator input / CLKIN |
| Pin 33 | OSC2 — Crystal oscillator output / CLKOUT |
| Pin 34 | RC0 — PORTC I/O bit 0 |
| Pin 35 | RC1 — PORTC I/O bit 1 / CCP2 |
| Pin 36 | RC2 — PORTC I/O bit 2 / CCP1 |
| Pin 37 | RD4 — PORTD I/O bit 4 / PSP data |
| Pin 38 | RD5 — PORTD I/O bit 5 / PSP data / CCP2 alt |
| Pin 39 | RD6 — PORTD I/O bit 6 / PSP data |
| Pin 40 | RD7 — PORTD I/O bit 7 / PSP data |
| Pin 41 | VSS — Ground reference |
| Pin 42 | VDD — Positive supply |
| Pin 43 | RB0 — PORTB I/O bit 0 / INT0 / AN12 |
| Pin 44 | RB1 — PORTB I/O bit 1 / AN10 |
Typical Applications
PIC18LF4550T-I/ML is suitable for 6 applications: USB HID Peripheral (Keyboard, Mouse, Custom HID), USB CDC Virtual COM Port Bridge, Industrial Sensor Interface with USB Logging, Battery-Powered USB Data Logger, USB Bootloader Host for Field Firmware Updates, Consumer USB Charging Controller.
USB HID Peripheral (Keyboard, Mouse, Custom HID)
The PIC18LF4550T-I/ML is well-suited to USB HID peripherals because it integrates a Full-Speed USB 2.0 SIE plus transceiver and 3.3 V regulator on-chip, eliminating the external PHY and reducing BOM. At 48 MHz the MIPS budget comfortably runs the Microchip USB stack plus HID report parsing. Place 100 nF plus 4.7 uF on VUSB3V3 and route D+/D- as a 90 ohm differential pair with the on-chip pull-up resistor enabled in firmware.
Recommended
USB CDC Virtual COM Port Bridge
For USB-to-UART bridge applications the PIC18LF4550T-I/ML converts a USB host port into a virtual COM port visible to the host OS without external drivers on Windows/macOS/Linux. The EUSART runs up to 115.2 kbaud cleanly and the MSSP adds I2C/SPI pass-through. The wide-voltage 2.0-5.5 V LF core lets the same firmware serve 3.3 V target MCUs and 5 V legacy RS-232 transceivers via a single bridge PCB.
Recommended
Industrial Sensor Interface with USB Logging
The 10-bit 13-channel ADC plus 2 analog comparators make the PIC18LF4550T-I/ML a good fit for a multi-channel sensor module that streams samples over USB to a host PC. Industrial -40 C to +85 C temperature rating allows deployment in factory environments, while the 32 KB Flash accommodates averaging, calibration, and a USB-CDC logging task. Use the 16-bit timer for precise sampling intervals and trigger DMA-style double buffering in firmware.
Recommended
Battery-Powered USB Data Logger
The PIC18LF4550T-I/ML's wide 2.0-5.5 V VDD range and nanoWatt sleep modes (down to <1 uA typical in sleep) let it run directly from a single-cell Li-ion or 2xAA battery pack while still streaming data over USB when docked. The internal 31 kHz low-power oscillator keeps time-stamping accurate during sleep, and the on-chip 3.3 V USB regulator draws only when the USB cable is plugged in, preserving battery life.
Recommended
USB Bootloader Host for Field Firmware Updates
Many production designs reserve the PIC18LF4550T-I/ML as a USB bootloader host that re-flashes a downstream application MCU over SPI/I2C, taking advantage of the 32 KB Flash to host both a custom bootloader and the USB stack. The ICSP capability allows the bootloader to update itself in the field, while the EUSART provides a fallback RS-232 path. Industrial temperature rating ensures reliable bootloading in field-deployed enclosures.
Recommended
Consumer USB Charging Controller
The PIC18LF4550T-I/ML can serve as a USB-host-side charging controller that negotiates USB-IF battery charging profiles with an upstream device while logging charge current via the ADC. The 35 I/O lines can drive status LEDs, button inputs, and an LCD or OLED display without external logic. The wide voltage range supports both 5 V VBUS-powered operation and battery-only operation when the USB host is disconnected.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF4550T-I/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18LF4550-I/ML | PIC18F4550T-I/ML |
|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-VQFN Exposed Pad (8x8 mm) | 44-VQFN EP (8x8 mm) - identical | 44-VQFN EP (8x8 mm) - identical |
| Supply Voltage Range | 2.0 V to 5.5 V | 2.0 V to 5.5 V - identical | 4.2 V to 5.5 V (narrower) |
| Program Memory | 32 KB Flash | 32 KB Flash - identical | 32 KB Flash - identical |
| RAM | 2 KB | 2 KB - identical | 2 KB - identical |
| Maximum CPU Frequency | 48 MHz | 48 MHz - identical | 48 MHz - identical |
| Number of I/O | 35 | 35 - identical | 35 - identical |
| USB Interface | Full-Speed USB 2.0 on-chip | Full-Speed USB 2.0 on-chip - identical | Full-Speed USB 2.0 on-chip - identical |
| Operating Temperature | -40 C to +85 C (Industrial) | -40 C to +85 C - identical | -40 C to +85 C - identical |
| Packaging Form | Tape & Reel ('T' suffix) | Tray ('I' suffix without 'T') | Tape & Reel - identical |
Key Differentiators
- Wide-voltage LF core (vs PIC18F4550T-I/ML)
- On-chip Full-Speed USB PHY (vs PIC18LF4553T-I/ML (obsolete sibling))
- Tape-and-Reel factory packaging (vs PIC18LF4550-I/ML (tray))
Design Notes
Estimated: For the 44-VQFN Exposed Pad package on a 4-layer JEDEC JESD51-7 test board, theta-JA is approximately 32 C/W. Solder the central exposed pad to a continuous ground plane with at least 8 thermal vias (0.3 mm drill, 1.0 mm pitch) to achieve the rated thermal performance. Without thermal vias the die temperature can rise 30-40 C above ambient at moderate CPU loads, exceeding the industrial 85 C rating.
The PIC18LF4550T-I/ML's on-chip USB 3.3 V regulator sources up to 250 mA but requires both 100 nF and 4.7 uF ceramic decoupling on the VUSB3V3 pin. Keep D+/D- traces as a 90 ohm differential pair of equal length, and place the USB connector within 50 mm of the device to meet USB 2.0 signal-integrity requirements. The MCU VDD range of 2.0-5.5 V means the same hardware can serve both 3.3 V and 5 V USB hosts by configuring the regulator enable bit in firmware.
Do not omit the ICSP pull-down on MCLR (RE3) - a 10 kohm to VDD is required for normal operation and must be removable by the programmer. Reserve RB6/PGC and RB7/PGD exclusively for ICSP during development, or implement a boot-mode jumper to release them for application use. Always include an ESD protection array (such as the USBLC6-2SC6) on the D+/D- lines if the USB connector is user-accessible, to survive IEC 61000-4-2 air-discharge events.
Estimated: The 13-channel 10-bit ADC achieves approximately 1 LSB INL and 2 LSB DNL with a 10 kHz sampling rate when source impedance is below 2.5 kohm and an external 100 nF bypass capacitor is placed on VREF+. Use the highest available AD acquisition time (20 TAD) in the ADC configuration register for high-impedance sensors. For capacitive-touch or sigma-delta conversions, consider the dedicated PIC18F46K22 or PIC18F25K50 instead - they offer 12-bit ADC variants.
Keep the 48 MHz crystal traces (OSC1/OSC2) as short as possible and surround them with a ground guard ring to avoid radiating 48 MHz harmonics onto the USB differential pair. Place the crystal within 5 mm of the MCU. If using the internal oscillator block to free PCB area, the PLL-derived 48 MHz is factory-trimmed to +/- 0.25 % across the -40 C to +85 C industrial range, sufficient for USB Full-Speed compliance without external timing components.
Compliance Information
RoHS and lead-free compliant per Microchip product page. Not AEC-Q100 qualified - this part is not designed for automotive safety-critical applications. REACH compliance statement is published by Microchip but specific substance-concentration thresholds are listed only in the manufacturer's full material declaration (available under NDA).
