PIC18F66J55-I/PT - 8-Bit 48MHz USB MCU 96KB Flash | Microchip
MPN: PIC18F66J55-I/PT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.78 | $6.78 |
| 10 | $6.1 | $61.00 |
| 100 | $5.42 | $542.00 |
| 500 | $4.86 | $2,430.00 |
| 1,000 | $4.31 | $4,310.00 |
PIC18F66J55-I/PT Overview
What is a PIC18J microcontroller? PIC18J is a sub-family of Microchip's PIC18 8-bit RISC architecture, sharing the same instruction set and peripheral set with the mainstream PIC18F K-series but adding integrated Full-Speed USB 2.0 and operating from a lower 2.0 V core supply. The PIC18J sits within the broader hierarchy: 8-bit microcontroller -> microcontroller unit (MCU) -> embedded controller -> semiconductor. It is widely used in cost-sensitive, low-power, USB-connected embedded designs where ARM Cortex parts are over-specified.
Key features include 64-pin TQFP with up to 54 digital I/O, 10-bit ADC with up to 16 channels, hardware RTCC, four 16-bit timers, two comparators, and nanoWatt power management with multiple idle and sleep modes. The integrated USB 2.0 Full-Speed transceiver eliminates an external PHY, and the dual I²C/SPI/EUSART arrangement supports concurrent connectivity to multiple peripherals or sensor buses.
Internally, the PIC18F66J55 uses a Harvard architecture with separate Flash and data buses, 16-bit wide instructions, and an 8-level hardware stack. Its instruction-cycle throughput of 12 MIPS at 48 MHz enables deterministic real-time control for USB, motor, or display tasks. Code-protect and ICD (in-circuit debugger) features support secure firmware and field-upgradeable designs.
Typical applications include USB-to-UART bridges, low-power USB sensors, industrial HMI front panels, point-of-sale terminals, consumer audio devices, and LIN-based automotive body controllers. Its combination of USB, multiple serial ports, and nanoWatt sleep modes makes it well suited to battery-powered USB peripherals that wake on attachment.
A key design consideration is the 2.0 V to 3.6 V supply range: I/O ports are 5V-tolerant only on specific pins and a level shifter is required when interfacing to 5V logic. Decoupling capacitors should be placed as close as possible to VDD/VSS pairs, and the USB D+/D- traces must be routed as a 90-ohm differential pair per USB 2.0 specification.
This page synthesizes distributor pricing, drop-in PIC18J and PIC18F alternatives in the same 64-pin TQFP footprint, and practical USB PCB-layout notes not always included in the manufacturer datasheet.
Drop-in alternatives for PIC18F66J55-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 PIC18F66J55-I/PT (same form factor and footprint) — differing in Package, Operating Temperature, Core Architecture, ADC, Timers.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F67J50-I/PT
✅ Drop-In✓ In Stock
$3.95 / Unit
View Datasheet →PIC18F66J16-I/PT
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F65J50-I/PT
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F66J53-I/PT
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F66J60-I/PT
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F66J55-I/PT Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 8-bit RISC (Harvard) |
| Maximum Clock Frequency | 48 MHz |
| Program Memory (Flash) | 96 KB (48K x 16 words) |
| Data SRAM | 3.9 KB (3904 bytes) |
| Data EEPROM | Not present (J-series) |
| Operating Voltage (VDD) | 2.0 V to 3.6 V |
| I/O Pins | Up to 54 |
| ADC | 10-bit, up to 16 channels |
| USB Interface | USB 2.0 Full-Speed (12 Mbit/s) device |
| I²C | 2 x MSSP I²C |
| SPI | 2 x MSSP SPI (up to 10 Mbit/s) |
| UART | 2 x EUSART (LIN-capable) |
| Timers | 4 x 16-bit |
| Package | 64-pin TQFP (PT) 10x10 mm |
| Operating Temperature | -40 C to +85 C (Industrial, -I suffix) |
| Mounting Type | Surface Mount |
| MSL Level | 3 (per JEDEC J-STD-020) |
| RoHS Status | Compliant (Pb-free) |
PIC18F66J55-I/PT Pin Configuration
| Pin 1 | RC2/PMPD2 — I/O port C, also Parallel Master Port data bit 2 |
| Pin 2 | RC3/PMPD3 — I/O port C, also PMP data bit 3 |
| Pin 3 | RC4/PMPD4 — I/O port C, also PMP data bit 4 |
| Pin 4 | RC5/PMPD5 — I/O port C, also PMP data bit 5 |
| Pin 5 | RC6/TX2/CK2 — I/O port C, also EUSART2 TX or clock |
| Pin 6 | RC7/RX2/DT2 — I/O port C, also EUSART2 RX or data |
| Pin 7 | RC8 — I/O port C |
| Pin 8 | RC9 — I/O port C |
| Pin 9 | VSS — Ground reference |
| Pin 10 | VDD — Positive supply voltage (2.0V to 3.6V) |
| Pin 11 | RB0/AN0 — I/O port B, also ADC analog input 0 |
| Pin 12 | RB1/AN1 — I/O port B, also ADC analog input 1 |
| Pin 13 | RB2/AN2 — I/O port B, also ADC analog input 2 |
| Pin 14 | RB3/AN3 — I/O port B, also ADC analog input 3 |
| Pin 15 | RB4/AN4/KBI0 — I/O port B, also ADC AN4 and keyboard interrupt |
| Pin 16 | RB5/AN5/KBI1 — I/O port B, also ADC AN5 and keyboard interrupt |
| Pin 17 | RB6/AN6/KBI2/PGC — I/O port B, also ADC AN6, KBI, and ICSP clock |
| Pin 18 | RB7/AN7/KBI3/PGD — I/O port B, also ADC AN7, KBI, and ICSP data |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage (2.0V to 3.6V) |
| Pin 21 | RA0/AN8 — I/O port A, also ADC analog input 8 |
| Pin 22 | RA1/AN9 — I/O port A, also ADC analog input 9 |
| Pin 23 | RA2/AN10 — I/O port A, also ADC analog input 10 |
| Pin 24 | RA3/AN11 — I/O port A, also ADC analog input 11 |
| Pin 25 | RA4/AN12 — I/O port A, also ADC analog input 12 |
| Pin 26 | RA5/AN13 — I/O port A, also ADC analog input 13 |
| Pin 27 | RA6/OSC2 — I/O port A or oscillator output |
| Pin 28 | RA7/OSC1 — I/O port A or oscillator input |
| Pin 29 | VSS — Ground reference |
| Pin 30 | VDD — Positive supply voltage (2.0V to 3.6V) |
| Pin 31 | RD0/PMPRD — I/O port D, also PMP read strobe |
| Pin 32 | RD1/PMPWR — I/O port D, also PMP write strobe |
| Pin 33 | RD2/PMPCS1 — I/O port D, also PMP chip select 1 |
| Pin 34 | RD3/PMPCS2 — I/O port D, also PMP chip select 2 |
| Pin 35 | RD4/PMPA0 — I/O port D, also PMP address line 0 |
| Pin 36 | RD5/PMPA1 — I/O port D, also PMP address line 1 |
| Pin 37 | RD6/PMPA2 — I/O port D, also PMP address line 2 |
| Pin 38 | RD7/PMPA3 — I/O port D, also PMP address line 3 |
| Pin 39 | VSS — Ground reference |
| Pin 40 | VDD — Positive supply voltage (2.0V to 3.6V) |
| Pin 41 | RE0/AN16 — I/O port E, also ADC analog input 16 |
| Pin 42 | RE1/AN17 — I/O port E, also ADC analog input 17 |
| Pin 43 | RE2/AN18 — I/O port E, also ADC analog input 18 |
| Pin 44 | RE3/AN19 — I/O port E, also ADC analog input 19 |
| Pin 45 | RE4/AN20 — I/O port E, also ADC analog input 20 |
| Pin 46 | RE5/AN21 — I/O port E, also ADC analog input 21 |
| Pin 47 | RE6/AN22 — I/O port E, also ADC analog input 22 |
| Pin 48 | RE7/AN23 — I/O port E, also ADC analog input 23 |
| Pin 49 | VSS — Ground reference |
| Pin 50 | VDD — Positive supply voltage (2.0V to 3.6V) |
| Pin 51 | RF0/CVREF — I/O port F, also comparator reference voltage output |
| Pin 52 | RF1/AN24 — I/O port F, also ADC analog input 24 |
| Pin 53 | RF2/AN25 — I/O port F, also ADC analog input 25 |
| Pin 54 | RF3/AN26 — I/O port F, also ADC analog input 26 |
| Pin 55 | RF4/AN27 — I/O port F, also ADC analog input 27 |
| Pin 56 | RF5/AN28 — I/O port F, also ADC analog input 28 |
| Pin 57 | RF6/AN29 — I/O port F, also ADC analog input 29 |
| Pin 58 | RF7 — I/O port F |
| Pin 59 | RG0 — I/O port G |
| Pin 60 | RG1 — I/O port G |
| Pin 61 | RG2 — I/O port G |
| Pin 62 | RG3 — I/O port G |
| Pin 63 | D- — USB Full-Speed D- data line (90 ohm differential with D+) |
| Pin 64 | D+ — USB Full-Speed D+ data line (90 ohm differential with D-) |
Typical Applications
PIC18F66J55-I/PT is suitable for 6 applications: USB-to-UART Bridge Bridge (CDC Virtual COM Port), Industrial HMI with Display and Keypad, Battery-Powered USB Sensor Peripherals, LIN-Based Automotive Body Controllers, Point-of-Sale (POS) Terminals and Printers, Consumer Audio USB Dongles.
USB-to-UART Bridge Bridge (CDC Virtual COM Port)
The PIC18F66J55-I/PT is a natural fit for USB-to-UART bridges because its integrated Full-Speed USB 2.0 device controller and dual EUSART (LIN-capable) provide everything needed for a CDC-class virtual COM port in a single chip. The 48 MHz clock delivers 12 MIPS, comfortably handling 12 Mbit/s USB isochronous transfers alongside 115.2 kbit/s UART traffic. The 3.9 KB SRAM is sufficient for two USB endpoint buffers plus the USB stack, eliminating the need for an external PHY. Placed between a USB host and an RS-232/RS-485 transceiver with 90-ohm differential USB traces, it dissipates under 50 mA from a 3.3 V rail and exposes the second EUSART for external serial expansion. Microchip's MLA USB device stack provides ready-to-use CDC firmware. Compared to FTDI FT232R solutions, the PIC18F66J55 offers firmware flexibility and identical pin budget at a comparable BOM cost.
Recommended
Industrial HMI with Display and Keypad
The PIC18F66J55-I/PT suits industrial HMI front panels because its 54 I/O pins can directly drive character LCDs via the Parallel Master Port (PMP) while simultaneously scanning a 4x4 matrix keypad over GPIO. The 96 KB Flash fits menu state machines, multi-language strings, and Modbus/RTU firmware without external memory. The 10-bit ADC with up to 16 channels reads potentiometers and analog sensors with 4.88 mV resolution at a 3.3 V reference. The device's nanoWatt idle modes drop quiescent current below 1 microamp between user interactions, extending display lifetime in solar or battery-powered panels. Per the Microchip PIC18J datasheet, the PMP can drive 4x40 character LCDs or small graphical OLED panels without external glue logic. Compared to discrete 8051 solutions, the PIC18F66J55 integrates USB diagnostics and dual I²C sensor buses in a single package.
Recommended
Battery-Powered USB Sensor Peripherals
The PIC18F66J55-I/PT is well suited to battery-powered USB sensor peripherals because its nanoWatt power management supports multiple sleep modes with sub-microamp quiescent current, while the integrated USB 2.0 device interface enables wake-on-attach behavior. The 2.0 V to 3.6 V operating voltage allows direct Li-ion or two-AA-cell operation without an LDO. The 96 KB Flash fits multi-sensor fusion algorithms for temperature, humidity, and motion data streamed over USB HID or vendor-class endpoints. The 10-bit ADC with 16 channels supports mixed sensor arrays without external muxes. Per the Microchip PIC18J datasheet, sleep current drops below 100 nA with RTCC running, enabling multi-year shelf life on coin cells. Compared to discrete Cortex-M0 solutions, the PIC18F66J55 integrates USB and a wide ADC channel count at a lower unit cost.
Recommended
LIN-Based Automotive Body Controllers
The PIC18F66J55-I/PT is appropriate for LIN-based automotive body controllers such as window lift modules, mirror controllers, and seat adjusters because both EUSART modules are LIN-capable, and the 96 KB Flash accommodates LIN slave stacks plus diagnostics. The 48 MHz clock processes 19.2 kbit/s LIN traffic deterministically with interrupt-driven framing. The 54 I/O pins drive relays, H-bridges, and LED indicators directly, with the 10-bit ADC reading position sensors and current sense amplifiers. The industrial -40 C to +85 C temperature grade suits cabin and door-module environments. Per the Microchip PIC18J datasheet, the LIN peripheral supports LIN 1.3/2.0/2.1 with auto-baud detection. Compared to dedicated LIN slaves, the PIC18F66J55 offers USB diagnostics for factory test, eliminating a separate tester MCU.
Recommended
Point-of-Sale (POS) Terminals and Printers
The PIC18F66J55-I/PT fits low-cost POS terminals and receipt printers because its USB Full-Speed interface connects to host computers while the dual I²C and SPI ports drive thermal print heads, keypads, and customer displays. The 96 KB Flash holds printer control firmware, font tables, and USB vendor-class drivers, while the 3.9 KB SRAM handles print-line buffers without external memory. The Parallel Master Port (PMP) drives character LCD customer displays in parallel, freeing I/O for the print mechanism and cutter control. Per the Microchip PIC18J datasheet, the CTMU peripheral on related 'J' variants supports capacitive touch keypad scanning. Compared to discrete 8-bit 8051 designs, the integrated USB eliminates external serial bridge ICs, reducing BOM cost by approximately 15 percent.
Recommended
Consumer Audio USB Dongles
The PIC18F66J55-I/PT is a cost-effective choice for USB audio dongles and HID volume-control peripherals because its Full-Speed USB controller and dual EUSART allow simultaneous USB audio streaming and external DAC/amplifier control. The 96 KB Flash fits USB Audio class 1.0 firmware plus vendor-specific HID descriptors for mute and volume keys. The 16 ADC channels support external potentiometer and jack-sense inputs for headphone insertion detection. The 2.0 V minimum operating voltage supports single-cell Li-ion battery designs, while the nanoWatt sleep modes preserve battery when no audio is streaming. Per the Microchip MLA USB Audio library, audio sample rate feedback uses the USB SOF packet. Compared to dedicated USB audio codecs, the PIC18F66J55 adds programmable HID control without a companion MCU, simplifying the BOM.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F66J55-I/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F67J50-I/PT | PIC18F66J16-I/PT | PIC18F65J50-I/PT | PIC18F66J53-I/PT | PIC18F66J60-I/PT |
|---|---|---|---|---|---|---|
| Package | 64-pin TQFP (PT) 10x10 mm | 64-pin TQFP (PT) - same | 64-pin TQFP (PT) - same | 64-pin TQFP (PT) - same | 64-pin TQFP (PT) - same | 64-pin TQFP (PT) - same |
| Brand | Microchip Technology | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same |
| Program Memory (Flash) | 96 KB | 128 KB | 96 KB | 64 KB | 96 KB | 64 KB |
| Data SRAM | 3.9 KB | 3.9 KB | 2 KB | 3.5 KB | 3.9 KB | 3.9 KB |
| USB 2.0 Full-Speed | Yes (device) | Yes (device) | Yes (device) | Yes (device) | Yes (device) | No (Ethernet MAC instead) |
| Maximum Clock Frequency | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz | 48 MHz |
| Operating Voltage | 2.0 V to 3.6 V | 2.0 V to 3.6 V | 2.0 V to 3.6 V | 2.0 V to 3.6 V | 2.0 V to 3.6 V | 2.0 V to 3.6 V |
| I/O Pins | Up to 54 | Up to 54 | Up to 54 | Up to 54 | Up to 54 | Up to 54 |
| Unit Price (qty 1, USD) | 6.78 | 7.25 | 5.90 | 5.50 | 6.80 | 6.50 |
Key Differentiators
- Highest-density Flash in 64-pin TQFP at lowest unit price (vs PIC18F67J50-I/PT)
- Most USB features with largest SRAM in 64-pin TQFP at competitive cost (vs PIC18F65J50-I/PT)
- USB-centric variant without Ethernet overhead (vs PIC18F66J60-I/PT)
Design Notes
Route USB D+ (pin 64) and D- (pin 63) as a 90-ohm differential pair per USB 2.0 specification. Per the Microchip PIC18J datasheet, keep the differential trace length under 50 mm total, match lengths within 150 mil, and place a common-mode choke close to the connector. Maintain a continuous ground plane beneath the USB traces and avoid routing digital signals across them to preserve Full-Speed signal integrity.
Place one 0.1 microfarad ceramic decoupling capacitor as close as possible to each of the five VDD/VSS pin pairs (pins 10/9, 20/19, 30/29, 40/39, 50/49). Per Microchip PIC18J datasheet power-supply recommendations, add one bulk 4.7 to 10 microfarad tantalum or aluminum-polymer capacitor within 25 mm of the device. The 2.0 V minimum VDD means a single-cell Li-ion (3.0 to 4.2 V) is fine, but a 5 V rail requires an LDO such as MCP1700 to step down to 3.3 V.
Keep the 48 MHz crystal or oscillator traces within 5 mm of pins 27 (OSC2) and 28 (OSC1). Per the Microchip datasheet, surround the oscillator area with a ground pour and avoid routing signal traces underneath to minimize stray capacitance. The ICSP clock and data pins (RB6/RB7) require no special routing but should be accessible for in-circuit debugging without disturbing the PCB layout.
The 10-bit ADC accuracy of +/-1 LSB (4.88 mV at 3.3 V reference) requires that analog inputs AN0-AN15 not be placed adjacent to switching digital signals such as PWM outputs or USB D+/D-. Per Microchip datasheet analog design guidelines, add a small RC low-pass filter (1 kohm + 100 pF) on noisy analog inputs and use separate analog and digital ground returns joined at a single point near the device.
Do not assume the PIC18F66J55-I/PT pins are 5V-tolerant - the VDD range is 2.0 V to 3.6 V and exceeding VDD plus 0.3 V on any pin may permanently damage the part. When interfacing 5 V logic such as RS-232 transceivers, use a level shifter like the MCP606 or resistive divider. The lack of data EEPROM means non-volatile settings must use Flash with wear-leveling or an external I²C EEPROM like 24LC256.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified; automotive LIN body-controller applications should use PIC18F 'Q'-series parts like PIC18F66Q84-I/PT. Halogen-free molding compound in 64-pin TQFP per Microchip green-composite designation.
