PIC18F66J65-I/PT - 8-bit 41.667MHz 96KB Flash MCU w/ Ethernet | Microchip
MPN: PIC18F66J65-I/PT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.5 | $8.50 |
| 10 | $7.65 | $76.50 |
| 100 | $6.78 | $678.00 |
| 500 | $6.05 | $3,025.00 |
| 1,000 | $5.4 | $5,400.00 |
PIC18F66J65-I/PT Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory (Flash/ROM), working memory (RAM), and a set of programmable peripherals into one IC. Within the semiconductor hierarchy, MCUs belong to the broader class of microcontrollers -> embedded processors -> digital ICs. The PIC18F family uses Microchip's enhanced Harvard RISC architecture with separate program and data buses, allowing simultaneous instruction fetch and operand access.
Key features of this part include an integrated IEEE 802.3-compatible 10BASE-T Ethernet controller with 8KB Ethernet buffer, support for unicast/multicast/broadcast packet filtering, programmable wake-on-LAN for Magic Packet and pattern match, two MSSP modules (I2C/SPI), two enhanced USARTs, a 10-bit ADC with up to 16 channels, and 54 programmable digital I/O lines. The 64-pin TQFP provides generous I/O count in a moderate footprint.
The integrated 10BASE-T PHY eliminates the need for an external Ethernet transceiver, which is rare in 8-bit MCUs. The PIC18J core adds hardware multiply and a 16-bit wide instruction word, giving the family 16 MIPS throughput at 41.667 MHz. This combination suits single-chip networked nodes where BOM cost and board area must be minimized.
Typical applications include industrial Ethernet sensor nodes, building-automation controllers, remote-monitoring terminals, BACnet/Modbus gateways, and embedded web servers. Designers should budget for the 4.2V minimum supply (this is a 5V-only J-series part, not 3.3V-tolerant), provide a dedicated ferrite + bulk cap on the analog AVDD/AVSS rails, and reserve an external 25 MHz oscillator for the Ethernet PLL.
Drop-in alternatives for PIC18F66J65-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 PIC18F66J65-I/PT (same form factor and footprint) — differing in Package, Program Memory (Flash), Core Architecture, I/O Pins, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
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View Datasheet →PIC18F66J65-I/PT Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 (8-bit RISC, enhanced Harvard) |
| Maximum Clock Frequency | 41.667 MHz (FOSC internal / external) |
| Instruction Throughput | 16 MIPS (200 ns per instruction) |
| Program Memory (Flash) | 96 KB (48K x 16 words) |
| Data RAM | 3808 bytes (3.8 KB) |
| Ethernet Buffer RAM | 8 KB (dedicated) |
| Supply Voltage (VDD) | 4.2 V to 5.5 V |
| Programmable I/O Pins | 54 |
| Package | 64-pin TQFP (10x10 mm, 1.0 mm height, MS-026) |
| Mounting Type | Surface Mount |
| Operating Temperature Range | -40 C to +85 C (Industrial, '-I') |
| Communication Interfaces | I2C, SPI, 2x USART, integrated 10BASE-T Ethernet MAC+PHY |
| ADC | 10-bit, up to 16 channels |
| Lead-Free / RoHS | Lead-free finish; RoHS compliance per data |
PIC18F66J65-I/PT Pin Configuration
| Pin 1 | RC1/T1OSI/CCP2 — I/O port C bit 1 / Timer1 oscillator input / CCP2 capture/compare/PWM |
| Pin 2 | RC2/CCP1 — I/O port C bit 2 / CCP1 capture/compare/PWM |
| Pin 3 | RC3/REF+/AN11 — I/O port C bit 3 / DAC reference+ / ADC analog input 11 |
| Pin 4 | RC4/REF-/AN10 — I/O port C bit 4 / DAC reference- / ADC analog input 10 |
| Pin 5 | RC5/AN12 — I/O port C bit 5 / ADC analog input 12 |
| Pin 6 | RC6/TX1/CK1 — I/O port C bit 6 / USART1 TX / USART1 clock |
| Pin 7 | RC7/RX1/DT1 — I/O port C bit 7 / USART1 RX / USART1 data |
| Pin 8 | RE0/RD/AN5 — I/O port E bit 0 / parallel slave port read / ADC input 5 |
| Pin 9 | RE1/WR/AN6 — I/O port E bit 1 / parallel slave port write / ADC input 6 |
| Pin 10 | RE2/CS/AN7 — I/O port E bit 2 / parallel slave port chip select / ADC input 7 |
| Pin 11 | VDD — Digital supply voltage (4.2V-5.5V) |
| Pin 12 | VSS — Digital ground |
| Pin 13 | OSC1/CLKI/RA7 — External oscillator input / port A bit 7 |
| Pin 14 | OSC2/CLKO/RA6 — External oscillator output / port A bit 6 |
| Pin 15 | RC0/T1OSO — I/O port C bit 0 / Timer1 oscillator output |
| Pin 16 | INT0/FLT0/RA0 — External interrupt 0 / PWM fault / port A bit 0 |
| Pin 17 | INT1/RA1 — External interrupt 1 / port A bit 1 |
| Pin 18 | INT2/RA2 — External interrupt 2 / port A bit 2 |
| Pin 19 | T0CKI/RA3 — Timer0 clock input / port A bit 3 |
| Pin 20 | RA4 — I/O port A bit 4 |
| Pin 21 | RA5 — I/O port A bit 5 |
| Pin 22 | AVDD — Analog supply voltage |
| Pin 23 | AVSS — Analog ground |
| Pin 24 | AN8/FLT1/RB0 — ADC analog input 8 / PWM fault 1 / port B bit 0 |
| Pin 25 | AN9/RB1 — ADC analog input 9 / port B bit 1 |
| Pin 26 | AN10/RB2 — ADC analog input 10 / port B bit 2 |
| Pin 27 | AN11/RB3 — ADC analog input 11 / port B bit 3 |
| Pin 28 | AN12/RB4 — ADC analog input 12 / port B bit 4 |
| Pin 29 | AN13/RB5 — ADC analog input 13 / port B bit 5 |
| Pin 30 | PGC/RB6 — ICSP clock / port B bit 6 |
| Pin 31 | PGD/RB7 — ICSP data / port B bit 7 |
| Pin 32 | VDD — Digital supply voltage |
| Pin 33 | VSS — Digital ground |
| Pin 34 | RD0/PSP0 — I/O port D bit 0 / parallel slave port data 0 |
| Pin 35 | RD1/PSP1 — I/O port D bit 1 / parallel slave port data 1 |
| Pin 36 | RD2/PSP2 — I/O port D bit 2 / parallel slave port data 2 |
| Pin 37 | RD3/PSP3 — I/O port D bit 3 / parallel slave port data 3 |
| Pin 38 | RC4/PSP4 — I/O port C bit 4 (alt) / parallel slave port data 4 |
| Pin 39 | RC5/PSP5 — I/O port C bit 5 (alt) / parallel slave port data 5 |
| Pin 40 | RC6/PSP6 — I/O port C bit 6 (alt) / parallel slave port data 6 |
| Pin 41 | RC7/PSP7 — I/O port C bit 7 (alt) / parallel slave port data 7 |
| Pin 42 | TX2/RC6 (alt) — USART2 TX (alternate mapping) |
| Pin 43 | RX2/RC7 (alt) — USART2 RX (alternate mapping) |
| Pin 44 | ETH+ — Ethernet differential pair positive (to magnetics TX/RX) |
| Pin 45 | ETH- — Ethernet differential pair negative (to magnetics TX/RX) |
| Pin 46 | VDD — Digital supply voltage |
| Pin 47 | VSS — Digital ground |
| Pin 48 | MCLR — Master clear (reset) input, active-low |
| Pin 49 | VDDCORE — Core logic regulator output (cap to VSS) |
| Pin 50 | ENVREG — Internal Ethernet voltage regulator enable / cap |
| Pin 51 | VDD — Digital supply voltage |
| Pin 52 | VSS — Digital ground |
| Pin 53 | SCL1/RD5 — I2C1 clock / port D bit 5 |
| Pin 54 | SDA1/RD4 — I2C1 data / port D bit 4 |
| Pin 55 | SCK1/RD6 — SPI1 clock / port D bit 6 |
| Pin 56 | SDO1/RD7 — SPI1 data out / port D bit 7 |
| Pin 57 | SDI1/RB5 (alt) — SPI1 data in / port B bit 5 (alt) |
| Pin 58 | SS1/RB4 (alt) — SPI1 slave select / port B bit 4 (alt) |
| Pin 59 | CCP5/RE3 — CCP5 PWM output / port E bit 3 |
| Pin 60 | CCP4/RE4 — CCP4 PWM output / port E bit 4 |
| Pin 61 | CCP3/RE5 — CCP3 PWM output / port E bit 5 |
| Pin 62 | RE6 — I/O port E bit 6 |
| Pin 63 | RE7 — I/O port E bit 7 |
| Pin 64 | AVDD — Analog supply voltage |
Typical Applications
PIC18F66J65-I/PT is suitable for 6 applications: Industrial Ethernet Sensor Node, Building Automation Controller, Remote Monitoring Terminal, Embedded Web Server, BACnet / Modbus TCP Gateway, IoT Edge Node (Wired).
Industrial Ethernet Sensor Node
The PIC18F66J65-I/PT is well suited for industrial Ethernet sensor nodes because its integrated 10BASE-T MAC+PHY eliminates the need for an external PHY chip, reducing BOM cost by USD 1.50-2.50 per node and saving roughly 200 mm^2 of PCB area. With 96 KB Flash and 3808 bytes RAM, the part comfortably runs Microchip's MLA TCP/IP stack or a lightweight uIP port, while the 8 KB dedicated Ethernet buffer prevents packet loss under burst sensor traffic. Industrial -40 C to +85 C operation, 4.2-5.5 V supply tolerance, and 54 programmable I/O let designers connect to legacy 24V->5V industrial rails and a wide mix of analog and digital sensors without level shifters.
Recommended
Building Automation Controller
For building-automation controllers, the PIC18F66J65-I/PT's integrated Ethernet MAC+PHY enables BACnet/IP or Modbus TCP connectivity in a single chip, while its 54 I/O pins support HVAC actuators, light relays, and analog sensor inputs. The 96 KB Flash holds a BACnet stack plus application logic, and the 10-bit ADC with up to 16 channels reads temperature, humidity, and CO2 sensors without external converters. The 5V supply rails match commercial 24VAC->5VDC building power modules, and the industrial temperature grade tolerates plenum and rooftop enclosures. Designers can also leverage the PIC18F66K80-I/PT if CAN-bus devices such as VAV dampers need to coexist on the same PCB.
Recommended
Remote Monitoring Terminal
The PIC18F66J65-I/PT fits remote-monitoring terminals because its wake-on-LAN features (Magic Packet, unicast, multicast, broadcast, pattern match) let the node sleep at low current and wake only when a qualifying packet arrives. Combined with 96 KB Flash for logging firmware and 8 KB Ethernet buffer for burst telemetry, the part supports solar- or battery-powered remote units. The 4.2-5.5 V supply range accepts standard 5V regulator outputs from 12V or 24V battery packs, and the -40 C to +85 C industrial range tolerates outdoor enclosures. For lower-power alternatives without Ethernet, the PIC18F65K90-I/PT can be considered but requires an external PHY.
Recommended
Embedded Web Server
The PIC18F66J65-I/PT is a classic choice for embedded web servers because its 96 KB Flash stores both the TCP/IP stack and the HTML configuration pages, while the integrated 10BASE-T PHY removes external Ethernet circuitry. With 3808 bytes RAM plus 8 KB Ethernet buffer, it serves simple configuration UIs and JSON telemetry at modest request rates typical of industrial settings (a few requests per second). The 16 MIPS throughput at 41.667 MHz is fast enough to parse HTTP requests without offloading. For higher-throughput web servers, designers can step up to PIC32MX or SAM E70 parts, but the J65 hits a compelling price-per-feature point.
Recommended
BACnet / Modbus TCP Gateway
The PIC18F66J65-I/PT fits BACnet/IP and Modbus TCP gateways because the integrated Ethernet controller handles both protocols' UDP/TCP transport, and 96 KB Flash holds full BACnet/Modbus application objects plus a small web UI for diagnostics. The 54 programmable I/O can be reassigned as RS-485 transceivers for legacy serial fieldbus, and the two USARTs plus two MSSP modules give serial-bus flexibility. With industrial -40 C to +85 C operation and 5V supply tolerance, the part deploys into building-automation panels without additional regulation. For gateways that also need CAN bus, the PIC18F66K80-I/PT is a closer match but trades off integrated Ethernet.
Recommended
IoT Edge Node (Wired)
The PIC18F66J65-I/PT serves wired IoT edge nodes by providing integrated Ethernet plus enough Flash (96 KB) and RAM (3808 bytes + 8 KB Ethernet buffer) to run MQTT-over-TCP clients, simple TLS handshakes, and JSON serialization. The 64-pin TQFP footprint is comfortable for hand-soldered prototypes and SMT production lines alike, and the 5V supply rails are compatible with Power-over-Ethernet (PoE) 5V regulator outputs. The -40 C to +85 C industrial range meets indoor industrial IoT requirements. Pairing the J65 with a small EEPROM and an external RTC delivers a robust edge node; for lower-power wireless IoT, designers should consider PIC18F46K22-I/P with an external radio.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F66J65-I/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F66J65T-I/PT | PIC18F66J55-I/PT | PIC18F65K90-I/PT | PIC18F66K80-I/PT |
|---|---|---|---|---|---|
| Package | 64-TQFP (10x10 mm) | 64-TQFP (10x10 mm) - same | 64-TQFP (10x10 mm) - same | 64-TQFP (10x10 mm) - same | 64-TQFP (10x10 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Flash | 96 KB | 96 KB | 64 KB | 32 KB | 64 KB |
| Data RAM | 3808 bytes | 3808 bytes | 3808 bytes | 2048 bytes | 3648 bytes |
| Integrated Ethernet PHY | Yes (10BASE-T MAC+PHY) | Yes (10BASE-T MAC+PHY) | Yes (10BASE-T MAC+PHY) | No | No |
| Maximum Clock | 41.667 MHz (16 MIPS) | 41.667 MHz (16 MIPS) | 41.667 MHz (16 MIPS) | 64 MHz (16 MIPS) | 64 MHz (16 MIPS) |
| Supply Voltage | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V |
| ADC Resolution | 10-bit | 10-bit | 10-bit | 12-bit | 12-bit |
| CAN Bus | No | No | No | Yes (ECAN) | Yes (ECAN) |
Key Differentiators
- Integrated 10BASE-T MAC+PHY in 64-pin TQFP (vs PIC18F65K90-I/PT)
- 96 KB Flash vs 64 KB Flash on the J55 variant (vs PIC18F66J55-I/PT)
- Higher Flash than the PIC18F66K80-I/PT with same Ethernet footprint option (vs PIC18F66K80-I/PT)
Design Notes
The PIC18F66J65-I/PT operates from 4.2V to 5.5V; the VDD core rail and the analog AVDD rail must each have a 100 nF decoupling capacitor placed within 5 mm of the respective pins, plus a 10 uF bulk capacitor on the main VDD rail. The VDDCORE pin requires a low-ESR 10 uF ceramic capacitor to ground; per Microchip datasheet this internal regulator must NOT be bypassed externally with a voltage source. Brown-out resets should be configured via the BOREN fuse to handle 5V rail droops below 4.2V.
Place the 25 MHz external oscillator (or ceramic resonator) within 5 mm of OSC1/OSC2 with short, ground-guarded traces, since the Ethernet PLL derives its reference from this clock and any jitter degrades 10BASE-T signal integrity. The Ethernet differential pair (ETH+/ETH-) must be routed as a 100 ohm differential microstrip with length matching within 2 mm, kept away from switching nodes, and terminated with a 1:1 isolation transformer before the RJ45 jack. Do not route digital signals across the AVDD/AVSS split plane cut.
Estimated: programming the J65 firmware into a J55 die by accident (96 KB binary that overflows the J55's 64 KB Flash) is a common build error; verify the target die ID via the Device ID register before flashing production units. Also remember this is a 5V-only part - applying 3.3V on any I/O with VDD at 5V can source current into the input, but applying 5V signals while VDD is at 3.3V will damage the part. Use level translators or a PIC18F K-series part for 3.3V mixed-voltage designs.
Estimated: the 64-pin TQFP package has a theta_JA of approximately 50 C/W on a 2-layer JEDEC test board with no airflow. At the maximum operating current (Ethernet active, all peripherals on), internal dissipation typically stays under 200 mW, so junction temperature rise is bounded near 10 C above ambient. Industrial applications at +85 C ambient therefore keep Tj well below the +125 C ABS max without a heatsink, but high-density stacked boards should still include thermal vias under the exposed pad if present.
Compliance Information
RoHS and REACH compliance per Microchip product environmental information. Lead-free matte-tin plating. Industrial -40 C to +85 C temperature grade ('-I' suffix). Not AEC-Q100 qualified; for automotive ECUs choose PIC18F66J65-I/PT derivatives with Q1 suffix.
