PIC18F66J55T-I/PT - 8-bit USB MCU, 96KB Flash, 48MHz | Microchip
MPN: PIC18F66J55T-I/PT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9.12 | $9.12 |
| 10 | $8.21 | $82.10 |
| 100 | $7.34 | $734.00 |
| 500 | $6.58 | $3,290.00 |
| 1,000 | $5.92 | $5,920.00 |
PIC18F66J55T-I/PT Overview
What is a PIC18 microcontroller? A PIC18 is Microchip's 8-bit advanced Harvard-architecture RISC MCU family, sitting in the broader taxonomy of microcontrollers -> 8-bit microcontrollers -> CMOS flash MCUs -> embedded controllers. The 'J' suffix denotes the 2.0V-3.6V/4.2V-5.5V wide-range low-power family with internal voltage regulator and nanoWatt sleep modes. The PIC18F66J55 specifically targets designs that need USB connectivity, ample code space, and rich peripheral integration without an external voltage regulator.
Key features include 96 KB (48K x 16) Flash program memory, 3936 bytes of RAM, 54 digital I/O pins, an integrated Full-Speed (12 Mbit/s) USB 2.0 device/host/OTG transceiver, two EUSART (LIN-capable) ports, a Master I2C port, and an SPI port capable of up to 10 Mbit/s. The device integrates a 10-bit ADC (up to 16 channels), multiple timers, and nanoWatt technology with Idle, Sleep, and deep-sleep modes for battery-friendly designs.
Technically, the PIC18F66J55 uses an enhanced Harvard architecture with 16-bit instructions and 8-bit data path, a 32-level hardware stack, and an 8x8 hardware multiply engine. The on-chip 2.5V core regulator simplifies 5V single-rail designs, eliminating external LDO requirements in most cases. CIP (Core Independent Peripherals) such as CWG, MSSP, and configurable logic cells offload tasks from the CPU, increasing deterministic response for USB, motor control, and sensor interfaces.
Typical applications include Full-Speed USB peripherals (HID, CDC, vendor-class devices), embedded human-interface boards with capacitive touch sensing, industrial sensor hubs with LIN/UART bridging, low-power data loggers, and consumer audio/control panels. The 64-pin TQFP footprint is friendly for hand-soldered prototypes and standard reflow production lines.
When designing with the PIC18F66J55, ensure VUSB 3.3V is properly decoupled for the internal transceiver and respect the absolute maximum VDD of 5.5V. The /MCLR reset line must be pulled up through a resistor for reliable operation. MPLAB X IDE with XC8 compiler is the recommended toolchain for firmware development and debugging via ICSP.
This page synthesizes distributor pricing, drop-in alternative analysis, and practical design notes not consolidated on the manufacturer datasheet or single distributor page.
Drop-in alternatives for PIC18F66J55T-I/PT — 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 PIC18F66J55T-I/PT (same form factor and footprint) — differing in Operating Temperature, Package, ADC, I/O Pins, Program Memory (Flash).
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F66J55-I/PT
✅ Drop-In✓ In Stock
$4.31 / Unit
View Datasheet →PIC18F66J50T-I/PT
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →PIC18F65J50T-I/PT
✅ Drop-In✓ In Stock
$3.3 / Unit
View Datasheet →PIC18F66J55T-I/PT Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 8-bit RISC, enhanced Harvard |
| Program Memory (Flash) | 96 KB (48K x 16 words) |
| Data RAM | 3936 bytes (3.8 KB) |
| Maximum CPU Speed | 48 MHz (12 MIPS) |
| Supply Voltage (VDD) | 4.2 V to 5.5 V |
| I/O Pins | 54 digital I/O |
| USB Interface | USB 2.0 Full-Speed (12 Mbit/s), device/host/OTG |
| Serial Interfaces | 2x EUSART (LIN-capable), 1x I2C (Master), 1x SPI (up to 10 Mbit/s) |
| ADC | 10-bit, up to 16 channels |
| Timers | Multiple 8/16-bit timers with capture/compare |
| Package | TQFP-64 (PT), 10x10 mm |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial) |
| RoHS Status | Compliant |
PIC18F66J55T-I/PT Pin Configuration
| Pin 1 | RC0/T1OSO/T1CKI — I/O port C0 / Timer1 oscillator output |
| Pin 2 | RC1/T1OSI/CCP2 — I/O port C1 / Timer1 oscillator input / CCP2 |
| Pin 3 | RC2/CCP1 — I/O port C2 / CCP1 |
| Pin 4 | RC3 — I/O port C3 |
| Pin 5 | RC4 — I/O port C4 |
| Pin 6 | RC5 — I/O port C5 |
| Pin 7 | RC6/TX1/CK1 — EUSART1 TX / clock |
| Pin 8 | RC7/RX1/DT1 — EUSART1 RX / data |
| Pin 9 | RE0/RD — I/O port E0 / parallel slave port read |
| Pin 10 | RE1/WR — I/O port E1 / parallel slave port write |
| Pin 11 | RE2/CS — I/O port E2 / chip select |
| Pin 12 | VDD — Positive supply voltage |
| Pin 13 | VSS — Ground reference |
| Pin 14 | RB0/INT0 — I/O port B0 / external interrupt 0 |
| Pin 15 | RB1/INT1 — I/O port B1 / external interrupt 1 |
| Pin 16 | RB2/INT2 — I/O port B2 / external interrupt 2 |
| Pin 17 | RB3/INT3 — I/O port B3 / external interrupt 3 |
| Pin 18 | RB4 — I/O port B4 |
| Pin 19 | RB5 — I/O port B5 |
| Pin 20 | RB6/PGC — I/O port B6 / ICSP clock |
| Pin 21 | RB7/PGD — I/O port B7 / ICSP data |
| Pin 22 | VUSB — USB transceiver supply (3.3V internal regulator output) |
| Pin 23 | D+/D- — Differential USB data lines |
| Pin 24 | VDD — Positive supply voltage |
| Pin 25 | VSS — Ground reference |
| Pin 26 | RA0/AN0 — I/O port A0 / analog input 0 |
| Pin 27 | RA1/AN1 — I/O port A1 / analog input 1 |
| Pin 28 | RA2/AN2 — I/O port A2 / analog input 2 |
| Pin 29 | RA3/AN3 — I/O port A3 / analog input 3 |
| Pin 30 | RA4/AN4 — I/O port A4 / analog input 4 |
| Pin 31 | RA5/AN5 — I/O port A5 / analog input 5 |
| Pin 32 | RA6/OSC2 — I/O port A6 / crystal oscillator output |
| Pin 33 | RA7/OSC1 — I/O port A7 / crystal oscillator input |
| Pin 34 | VDD — Positive supply voltage |
| Pin 35 | VSS — Ground reference |
| Pin 36 | RD0 — I/O port D0 |
| Pin 37 | RD1 — I/O port D1 |
| Pin 38 | RD2 — I/O port D2 |
| Pin 39 | RD3 — I/O port D3 |
| Pin 40 | RD4 — I/O port D4 |
| Pin 41 | RD5 — I/O port D5 |
| Pin 42 | RD6 — I/O port D6 |
| Pin 43 | RD7 — I/O port D7 |
| Pin 44 | VSS — Ground reference |
| Pin 45 | RF0 — I/O port F0 |
| Pin 46 | RF1 — I/O port F1 |
| Pin 47 | RF2 — I/O port F2 |
| Pin 48 | RF3 — I/O port F3 |
| Pin 49 | RF4 — I/O port F4 |
| Pin 50 | RF5 — I/O port F5 |
| Pin 51 | RF6 — I/O port F6 |
| Pin 52 | RF7 — I/O port F7 |
| Pin 53 | RG0 — I/O port G0 |
| Pin 54 | RG1 — I/O port G1 |
| Pin 55 | RG2 — I/O port G2 |
| Pin 56 | RG3 — I/O port G3 |
| Pin 57 | RG4 — I/O port G4 |
| Pin 58 | AVDD — Analog positive supply voltage |
| Pin 59 | AVSS — Analog ground reference |
| Pin 60 | RH0 — I/O port H0 |
| Pin 61 | RH1 — I/O port H1 |
| Pin 62 | RH2 — I/O port H2 |
| Pin 63 | RH3 — I/O port H3 |
| Pin 64 | MCLR — Master clear (reset) input |
Typical Applications
PIC18F66J55T-I/PT is suitable for 6 applications: USB HID Peripherals (Keyboards / Mice / Custom HID), USB CDC Virtual COM Port Bridges, Industrial Sensor Hubs with LIN/UART Bridging, Capacitive Touch User Interfaces, Low-Power Data Loggers with USB Upload, Consumer Audio/Visual Control Panels.
USB HID Peripherals (Keyboards / Mice / Custom HID)
The PIC18F66J55T-I/PT is ideally suited for USB HID class devices because it integrates a Full-Speed USB 2.0 transceiver with on-chip pull-up resistors and a 48 MHz clock that meets the USB 12 Mbit/s timing spec with zero external components. With 96 KB Flash and 3.8 KB RAM, it comfortably hosts HID report descriptors, multi-endpoint buffers, and application logic for keyboards, mice, game controllers, and vendor-specific HID devices. Its 54 I/O pins support matrix-scanning key arrays, RGB LED PWM channels, and capacitive touch sensing. According to the Microchip USB stack guidelines, this part supports Microchip's free MLA USB framework, eliminating the need for a commercial RTOS.
Recommended
USB CDC Virtual COM Port Bridges
For USB-to-UART bridge designs, the PIC18F66J55T-I/PT provides Full-Speed USB plus two hardware EUSART channels, enabling simultaneous USB CDC and UART routing. The 96 KB Flash accommodates the CDC class driver, bootloader, and command parser; the 3936-byte RAM is sufficient for line-codec buffers and CDC notification endpoints. With its 5V-tolerant I/O, the MCU can interface directly to RS-232 or RS-485 transceivers without level shifting. Compared to discrete USB-to-UART bridge ICs, this part adds free GPIO and an extra UART for sensor aggregation.
Recommended
Industrial Sensor Hubs with LIN/UART Bridging
The PIC18F66J55T-I/PT's two LIN-capable EUSART channels make it a strong fit for industrial sensor hubs that bridge LIN bus nodes to a USB-connected host or a higher-level controller. The 10-bit ADC with up to 16 channels supports analog sensor arrays (temperature, pressure, current) alongside the digital interfaces, and the 54 I/O drive sensor enables logic, relay coils, and indicator LEDs without extra drivers. The industrial -40C to +85C temperature rating covers factory-floor deployments, while the nanoWatt sleep modes reduce quiescent draw below 100 nA for battery-backed sensor nodes.
Recommended
Capacitive Touch User Interfaces
With 54 I/O and CTMU (Charge Time Measurement Unit) hardware, the PIC18F66J55T-I/PT supports mTouch capacitive touch sensing on up to 32 channels without an external touch controller. The 96 KB Flash allows sophisticated gesture recognition, debounce algorithms, and user feedback state machines; the 3.8 KB RAM holds scan buffers and filter history. Its Full-Speed USB simplifies connection to a host PC for tuning or HID reporting. Compared to discrete touch ICs, this single-chip solution reduces BOM, PCB area, and firmware complexity for appliances, lighting controls, and consumer electronics.
Recommended
Low-Power Data Loggers with USB Upload
The PIC18F66J55T-I/PT's nanoWatt technology (Idle, Sleep, deep-sleep modes) plus Full-Speed USB suits battery-powered data loggers that record to internal Flash or external EEPROM and upload via USB when docked. The 96 KB Flash doubles as program and log storage, while the 3936-byte RAM buffers sample frames between writes. The 5V VDD range simplifies charging and Li-ion regulation. With wake-on-timer and wake-on-USART features, the device achieves multi-year battery life in periodic-sampling applications like environmental monitors or asset trackers.
Recommended
Consumer Audio/Visual Control Panels
The PIC18F66J55T-I/PT serves consumer A/V control panels (volume knobs, EQ displays, smart-home hubs) where USB connectivity, ample I/O for rotary encoders and RGB LEDs, and enough Flash for menu-driven UI are required. The 10-bit ADC reads potentiometers and analog sensors; the MSSP peripheral drives SPI displays. Compared to a separate MCU plus USB bridge, the integrated design reduces board cost and shortens firmware development time using Microchip's free MLA framework. The TQFP-64 footprint is well-suited to small-form-factor handheld controllers.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F66J55T-I/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F66J55-I/PT | PIC18F66J50T-I/PT | PIC18F65J50T-I/PT |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | TQFP-64 (PT) | TQFP-64 (PT) - same | TQFP-64 (PT) - same | TQFP-64 (PT) - same |
| Program Flash | 96 KB | 96 KB | 64 KB (-33%) | 32 KB (-67%) |
| RAM | 3936 bytes | 3936 bytes | 3936 bytes | 3936 bytes |
| Maximum Clock | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| USB 2.0 Full-Speed | Yes (integrated) | Yes | Yes | Yes |
| I/O Pins | 54 | 54 | 54 | 44 |
| Supply Voltage | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 4.2 V to 5.5 V |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
Key Differentiators
- Highest-density USB MCU in the PIC18F66J55 TQFP-64 footprint (vs PIC18F65J50T-I/PT)
- Full 96 KB Flash matches PIC18F66J55-I/PT (vs PIC18F66J50T-I/PT)
- Same die as PIC18F66J55-I/PT (tray vs T&R only) (vs PIC18F66J55-I/PT)
Design Notes
Decouple each VDD/VSS pair with 100 nF ceramic placed within 5 mm of the pin. For USB operation, add a 4.7 uF bulk capacitor on VUSB (pin 22) to stabilize the internal 3.3V LDO that powers the USB transceiver. The internal voltage regulator draws the entire core from VDD, so VDD noise above 50 mV ripple can couple into USB signaling - keep digital switching traces away from VDD traces.
Route the 90-ohm differential D+/D- USB pair with matched length within 150 mil and continuous ground reference plane beneath. Place the USB connector close to the MCU to minimize stub length. Use a 2-layer minimum stack-up with solid ground pour; 4-layer with dedicated VDD plane is preferred for EMI. According to the USB 2.0 specification, the D+/D- characteristic impedance should be 90 ohms differential.
Do not exceed VDD = 5.5V absolute maximum, or the internal 3.3V regulator will latch up. Always pull MCLR (pin 64) high through a 10 kohm resistor for reliable reset. Disable the internal USB pull-up resistor via firmware before entering deep sleep to avoid back-powering through the USB cable. Ensure ICSP pins RB6/RB7 are not driven by external circuitry during programming, or use isolation resistors.
The 48 MHz internal oscillator provides adequate accuracy for USB Full-Speed 12 Mbit/s signaling without an external crystal. If using an external crystal for tighter timing, place the crystal within 5 mm of OSC1/OSC2 (pins 32/33) and guard the traces with a grounded ring. According to the datasheet, EC mode with 48 MHz external clock is recommended for synchronized multi-MCU USB applications.
Compliance Information
RoHS and REACH compliant per Microchip product page. Industrial temperature grade -40C to +85C. Not AEC-Q100 qualified - choose PIC18F46J50-I/PT or PIC18F65K80T-I/PT for automotive applications.