PIC18F4685-I/PT - 8-bit 40MHz 96KB Flash MCU w/ ECAN | Microchip
MPN: PIC18F4685-I/PT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $10.47 | $10.47 |
| 10 | $9.85 | $98.50 |
| 100 | $8.92 | $892.00 |
| 500 | $8.05 | $4,025.00 |
| 1,000 | $7.2 | $7,200.00 |
PIC18F4685-I/PT Overview
Key features include 3328 bytes of RAM, 1024 bytes of EEPROM, 36 digital I/O lines, an 11-channel 10-bit ADC, and nanoWatt Technology for low-power operation. The device operates from 4.2V to 5.5V, supports the industrial -40C to +85C temperature range, and includes multiple serial interfaces (ECAN, I2C, SPI, USART) and two capture/compare/PWM modules.
An 8-bit microcontroller is a CPU whose internal data path and arithmetic logic unit process eight bits per clock. PIC18 fuses 8-bit legacy code compatibility with enhanced 16-bit-wide instruction words, enabling C-compiler-friendly code density while keeping peripheral integration high. PIC18F4685 sits inside the PIC18F family, which is Microchip's mid-range 8-bit MCU line used across automotive, industrial, and consumer embedded designs.
The PIC18F4685 utilizes a Harvard RISC architecture with a hardware multiplier, achieving 10 MIPS at 40 MHz. Its ECAN module complies with CAN 2.0B active specification, supporting both standard and extended identifiers, which makes it well-suited for in-vehicle body and powertrain networks. nanoWatt Technology (ultra-low-power modes including idle, sleep, and deep sleep) extends battery life in portable applications, with typical idle currents in the microamp range. The device supports in-circuit serial programming (ICSP) and in-circuit debugging through ICD.
Typical applications include automotive ECAN body and chassis networks, industrial CAN-bus sensor nodes, HVAC control systems, motor-control interfaces, building automation nodes, and embedded sensor hubs requiring 10-bit analog digitization and moderate on-chip storage.
When designing with this device, note that VDD must be decoupled with at least 0.1 uF ceramic capacitors placed within 5 mm of each power pin. The ECAN transceiver must be a separate external chip such as the MCP2551 or MCP2561; the PIC18F4685 contains only the protocol layer.
This page synthesizes distributor pricing, parametric data, and drop-in alternatives drawn from Microchip product family datasheets and XAIPART's curated engineering database.
Drop-in alternatives for PIC18F4685-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 PIC18F4685-I/PT (same form factor and footprint) — differing in Package, ADC, Operating Temperature, I/O Pins, Timers.
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Request AlternativesPIC18F4685-I/PT Maximum Ratings & Electrical Characteristics
| Family | PIC18F |
| Core | 8-bit PIC RISC |
| Program Memory Size | 96 KB (48K x 16) FLASH |
| RAM Size | 3328 bytes |
| EEPROM Size | 1 KB (1024 x 8) |
| Maximum CPU Frequency | 40 MHz |
| Supply Voltage | 4.2 V to 5.5 V |
| Number of I/O Pins | 36 |
| ADC | 11 x 10-bit |
| Package | 44-TQFP (10x10 mm) |
| Operating Temperature | -40C to +85C (Industrial) |
| ECAN Module | Yes (CAN 2.0B active) |
| Mounting Type | Surface Mount |
| MSL Level | 3 |
| RoHS Status | Compliant |
PIC18F4685-I/PT Pin Configuration
| Pin 1 | RC7/RX/DT — I/O port C bit 7 / USART RX / synchronous data |
| Pin 2 | RC6/TX/CK — I/O port C bit 6 / USART TX / synchronous clock |
| Pin 3 | RC5/SDO — I/O port C bit 5 / SPI data out |
| Pin 4 | RC4/SDI/SDA — I/O port C bit 4 / SPI data in / I2C data |
| Pin 5 | RC3/SCL — I/O port C bit 3 / I2C clock |
| Pin 6 | RC2/CCP1 — I/O port C bit 2 / Capture-Compare-PWM 1 |
| Pin 7 | RC1/CCP2 — I/O port C bit 1 / Capture-Compare-PWM 2 |
| Pin 8 | RC0 — I/O port C bit 0 |
| Pin 9 | OSC1/CLKI — Oscillator crystal input / external clock input |
| Pin 10 | OSC2/CLKO — Oscillator crystal output / clock output |
| Pin 11 | VSS — Ground reference |
| Pin 12 | VDD — Positive supply voltage (4.2V to 5.5V) |
| Pin 13 | MCLR/VPP/RE3 — Master clear reset / programming voltage / port E bit 3 |
| Pin 14 | RA0/AN0 — I/O port A bit 0 / analog channel 0 |
| Pin 15 | RA1/AN1 — I/O port A bit 1 / analog channel 1 |
| Pin 16 | RA2/AN2/VREF- — I/O port A bit 2 / analog channel 2 / ADC VREF- |
| Pin 17 | RA3/AN3/VREF+ — I/O port A bit 3 / analog channel 3 / ADC VREF+ |
| Pin 18 | RA4/T0CKI — I/O port A bit 4 / Timer 0 clock input |
| Pin 19 | RA5/AN4/SS — I/O port A bit 5 / analog channel 4 / SPI slave select |
| Pin 20 | AVSS — Analog ground |
| Pin 21 | AVDD — Analog positive supply |
| Pin 22 | RB7/AN15 — I/O port B bit 7 / analog channel 15 |
| Pin 23 | RB6/AN14 — I/O port B bit 6 / analog channel 14 |
| Pin 24 | RB5/AN13 — I/O port B bit 5 / analog channel 13 |
| Pin 25 | RB4/AN12 — I/O port B bit 4 / analog channel 12 |
| Pin 26 | RB3/AN11/CANTX — I/O port B bit 3 / analog channel 11 / ECAN transmit |
| Pin 27 | RB2/AN10/CANRX — I/O port B bit 2 / analog channel 10 / ECAN receive |
| Pin 28 | RB1/AN9 — I/O port B bit 1 / analog channel 9 |
| Pin 29 | RB0/AN8/INT0 — I/O port B bit 0 / analog channel 8 / external interrupt 0 |
| Pin 30 | VDD — Positive supply voltage (second pin) |
| Pin 31 | VSS — Ground reference (second pin) |
| Pin 32 | RD7/PSP7 — I/O port D bit 7 / parallel slave port bit 7 |
| Pin 33 | RD6/PSP6 — I/O port D bit 6 / parallel slave port bit 6 |
| Pin 34 | RD5/PSP5 — I/O port D bit 5 / parallel slave port bit 5 |
| Pin 35 | RD4/PSP4 — I/O port D bit 4 / parallel slave port bit 4 |
| Pin 36 | RC7/RX/DT (alt) — I/O port C bit 7 (secondary function) |
| Pin 37 | RD3/PSP3 — I/O port D bit 3 / parallel slave port bit 3 |
| Pin 38 | RD2/PSP2 — I/O port D bit 2 / parallel slave port bit 2 |
| Pin 39 | RD1/PSP1 — I/O port D bit 1 / parallel slave port bit 1 |
| Pin 40 | RD0/PSP0 — I/O port D bit 0 / parallel slave port bit 0 |
| Pin 41 | RE0/RD/AN5 — I/O port E bit 0 / read control / analog channel 5 |
| Pin 42 | RE1/WR/AN6 — I/O port E bit 1 / write control / analog channel 6 |
| Pin 43 | RE2/CS/AN7 — I/O port E bit 2 / chip select / analog channel 7 |
| Pin 44 | VDD — Positive supply voltage (third pin) |
Typical Applications
PIC18F4685-I/PT is suitable for 6 applications: Automotive ECAN Body Control Node, Industrial CAN-bus Sensor Hub, HVAC Building Automation Controller, Motor Control Interface Module, Embedded Sensor Data Logger, Medical Device CAN Interface Board.
Automotive ECAN Body Control Node
PIC18F4685-I/PT fits automotive ECAN body control because its integrated ECAN 2.0B active module handles 11-bit and 29-bit identifiers at the protocol layer, while 96 KB Flash stores both CAN stack and body-control application code. 40 MHz MIPS throughput is sufficient for real-time message arbitration and debounce routines across door modules, seat controllers, or lighting clusters. Place an MCP2551 or MCP2561 external transceiver between CANTX/CANRX and the physical bus; unlike a discrete CAN controller the on-chip ECAN removes one BOM line and reduces PCB area. The 11-channel 10-bit ADC reads thermistor, switch, and potentiometer inputs directly, simplifying the analog front end. Designers must validate against ISO 11898-2 and the OEM-specific CAN conformance test for production release.
Recommended
Industrial CAN-bus Sensor Hub
PIC18F4685-I/PT suits industrial CAN sensor hubs because its ECAN module plus 36 GPIO allows multi-sensor aggregation (temperature, pressure, level) and forwarding over CANopen or DeviceNet protocols. The 96 KB Flash stores CANopen stack libraries such as CanFestival, while 3328 bytes RAM handles PDO buffers. The 4.2-5.5V supply aligns with 24V industrial bus rails after local regulation. nanoWatt idle and sleep modes reduce average current to microamp levels, which is essential for battery-backed remote sensors. Unlike an MCU without ECAN, the on-chip controller eliminates external logic and cuts bill of materials by 20-30%. Place 100 nF decoupling within 5 mm of every VDD/VSS pair per Microchip layout guidelines.
Recommended
HVAC Building Automation Controller
PIC18F4685-I/PT fits HVAC controllers because its 36 I/O and 11-channel ADC handle analog temperature sensors, duct pressure transducers, and damper actuator feedback with no external multiplexer. The 96 KB Flash stores Modbus RTU or BACnet application layers, and the ECAN module lets multiple HVAC units communicate on a building automation bus. nanoWatt Technology extends battery life in wireless thermostat variants. Compared with a discrete ADC plus 8-bit MCU, the integrated 10-bit ADC plus ECAN shrinks PCB area by roughly 35%. Use the USART for RS-485 fallback and the SPI/I2C for local display or EEPROM expansion when required.
Recommended
Motor Control Interface Module
PIC18F4685-I/PT works in motor-control interface modules because its two Capture/Compare/PWM modules drive control signals to external gate drivers such as the MCP8024 or gate-driver discrete stages. The 11-channel 10-bit ADC samples phase currents and back-EMF for sensorless commutation algorithms, while ECAN links the module to a central vehicle or machine controller. The 40 MHz CPU speed supports 10 kHz control loop rates without overclocking, which is adequate for brushed DC, stepper, or low-speed BLDC commutation. The 4.2-5.5V supply aligns with industrial 5V rails, while the 44-TQFP footprint provides ample thermal headroom at typical interface currents below 50 mA.
Recommended
Embedded Sensor Data Logger
PIC18F4685-I/PT supports data-logger designs because the 1024-byte EEPROM provides non-volatile parameter storage while 3328 bytes of RAM buffers sensor bursts before forwarding via ECAN or USART. The 11-channel ADC reads multiple analog inputs simultaneously, and 96 KB Flash stores file-system libraries such as FAT-Lite for optional SD-card interfaces via SPI. nanoWatt Technology places the MCU in sleep mode between sensor readings, achieving average currents below 100 uA from a single-cell Li-ion supply. Compared with an 8-bit MCU without ECAN, the on-chip controller simplifies networked data-acquisition nodes. Add an external MCP1541 voltage reference if higher ADC accuracy is required.
Recommended
Medical Device CAN Interface Board
PIC18F4685-I/PT fits medical-device CAN interface boards because its industrial -40C to +85C range plus integrated ECAN supports reliable communication in hospital bed, infusion-pump, or patient-monitor networks. The 11-channel 10-bit ADC reads redundant analog safety inputs while ECAN forwards telemetry to a central station. The 96 KB Flash stores IEC 62304-relevant firmware modules and bootloader code, while the 1024-byte EEPROM holds calibration constants. Unlike an MCU without ECAN, the on-chip module eliminates external bus controllers and reduces EMC-sensitive trace length. Validate the full design against IEC 60601-1 and the OEM's risk-management file before release; this Microchip part does not carry medical-grade certification by itself.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F4685-I/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4685-I/P |
|---|---|---|
| Package | 44-TQFP (10x10 mm) | 40-Pin PDIP - different footprint, NOT drop-in |
| Brand | Microchip Technology | Microchip Technology - same brand |
| Flash Memory | 96 KB | 96 KB - identical |
| RAM | 3328 bytes | 3328 bytes - identical |
| ECAN Module | Yes (CAN 2.0B active) | Yes (CAN 2.0B active) - identical |
| Supply Voltage | 4.2 V to 5.5 V | 4.2 V to 5.5 V - identical |
| Operating Temperature | -40C to +85C | -40C to +85C - identical |
| PCB Footprint Compatibility | TQFP-44 surface mount | PDIP-40 through-hole - requires PCB rework, NOT a drop-in |
Key Differentiators
- Largest Flash in the PIC18F4685 TQFP-44 family (vs PIC18F4585-I/PT)
- Higher ADC channel count than K-series siblings (vs PIC18F45K80-I/PT)
- Mature ECAN 2.0B firmware ecosystem (vs PIC18F4685-I/P (PDIP))
Design Notes
The PIC18F4685-I/PT requires VDD and VSS pairs on pins 12/11, 30/31, and 44 (VSS internally bonded or shared depending on revision). Place a 100 nF ceramic decoupling capacitor within 5 mm of each VDD pin per Microchip PIC18F layout guidelines. A bulk 10 uF tantalum or ceramic capacitor on the supply rail reduces switching-induced dips during ECAN transmissions, which can draw short bursts above 50 mA.
Route CANTX (RB3) and CANRX (RB2) as a short differential pair to the external MCP2551/MCP2561 transceiver, keeping the trace length under 50 mm to maintain CAN timing margins. Place the transceiver close to the bus connector, then route its RXD/TXD back to the MCU. Use a ground guard or via fence around the bus traces to limit radiated emissions; the ECAN module does not include integrated EMC filtering.
Estimated: at 40 MHz clock with ECAN active and both CCP modules running, the PIC18F4685-I/PT draws approximately 22 mA from a 5 V supply, giving a power dissipation near 110 mW and a junction temperature rise of about 9 C over ambient using the 44-TQFP theta_JA of roughly 50 C/W. Designers commonly forget that the ECAN module requires configuration of the CIOCON, BRGCON1/2/3 registers before bus activity; without correct baud-rate programming, the bus stays silent and the firmware appears to hang. The MCLR pin must be pulled high through a 10 kohm resistor for normal operation.
The 10-bit ADC achieves specified linearity only when the source impedance is below 2.5 kohm and acquisition time is at least 1.4 us. Driving analog inputs from higher-impedance sensors (such as 10 kohm thermistors) requires a buffer op-amp such as the MCP601 to avoid gain errors. Use the dedicated AVSS/AVDD pins with separate analog ground return to digital ground at a single point to prevent digital switching noise from coupling into ADC readings.
Compliance Information
RoHS compliant per Microchip product page and FindMyChip distributor listing. The standard -I (industrial) temperature grade does not carry AEC-Q100 automotive qualification - look for the PIC18F4685-I/PTVAO automotive variant if AEC-Q100 is required. Halogen-free per Microchip green-compliance statement.