PIC18LF4685-I/PT - 8-Bit MCU, 96KB Flash, ECAN, TQFP-44 | Microchip
MPN: PIC18LF4685-I/PT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.46 | $8.46 |
| 10 | $7.78 | $77.80 |
| 100 | $6.93 | $693.00 |
| 500 | $6.24 | $3,120.00 |
| 1,000 | $5.55 | $5,550.00 |
PIC18LF4685-I/PT Overview
A microcontroller (MCU) is a single-chip computer containing a processor, memory, and peripherals designed for embedded control. Within the semiconductor hierarchy, an 8-bit MCU like the PIC18LF4685 occupies the tier below 32-bit microcontrollers (e.g., ARM Cortex-M) and above simple programmable logic, optimized for cost-sensitive, deterministic control loops. The PIC18 family specifically targets applications needing CAN networking, analog integration, and automotive-grade reliability in a single device.
Key features of the PIC18LF4685 include a wide operating voltage range of 2.0V to 5.5V (LF variant), nanoWatt technology for sleep currents below 100 nA, and an enhanced CAN 2.0B module supporting both standard and extended identifiers. The 10-bit ADC supports up to 13 input channels with auto-acquisition, while hardware PWM modules include Capture/Compare/PWM (CCP) and Enhanced CCP (ECCP) peripherals. The device integrates an 8x8 hardware multiplier, multiple serial protocols (I2C, SPI, USART with IrDA), and supports In-Circuit Serial Programming (ICSP) for field updates.
The PIC18LF4685 architecture uses a 16-bit modified Harvard structure with separate program and data buses, enabling single-cycle instruction execution with a two-stage pipeline. The ECAN module includes acceptance filters, masks, and time-stamping, making the MCU suitable for industrial and automotive networked nodes. nanoWatt features like Sleep mode, Idle mode, and selective peripheral shutdown reduce quiescent current for battery-backed designs, while the on-chip 32 kHz oscillator supports real-time clock operation without external crystals.
Typical applications include automotive body and powertrain ECUs, industrial CAN nodes, sensor interface boards, and motor control subsystems. The combination of ECAN, ADC, and PWM peripherals enables single-chip BLDC motor controllers, HVAC actuators, and OBD-II diagnostic interfaces. The LF voltage range (2.0V-3.6V typical, 5.5V max) makes it compatible with 3.3V and 5V mixed-signal designs.
When designing with this device, ensure the CAN bus is terminated with 120-ohm resistors at both ends of the segment. Decouple VDD with at least 100 nF ceramic capacitors placed within 5 mm of the power pins, and use a dedicated ground plane to minimize EMI on the high-speed CAN lines. The MCLR pin should be pulled high through a 10 kohm resistor unless external reset is required.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes from Microchip datasheet DS39661B, going beyond the manufacturer datasheet alone.
Drop-in alternatives for PIC18LF4685-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 PIC18LF4685-I/PT (same form factor and footprint) — differing in ADC, Timers, Package, Operating Temperature, Communication.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F4685-I/PT
✅ Drop-In✓ In Stock
$7.2 / Unit
View Datasheet →PIC18LF4685T-I/PT
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF4680-I/PT
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF45K80-I/PT
✅ Drop-In✓ In Stock
$4.1 / Unit
View Datasheet →PIC18LF4585-I/PT
✅ Drop-In✓ In Stock
$6.34 / Unit
View Datasheet →PIC18LF4685-I/PT Maximum Ratings & Electrical Characteristics
| Family | PIC18F |
| Core | 8-bit PIC RISC |
| Program Memory | 96 KB Flash |
| RAM | 3.25 KB |
| EEPROM | 1024 bytes |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Operating Voltage Range | 2.0 V to 5.5 V |
| ADC | 10-bit, up to 13 channels |
| CAN Module | ECAN 2.0B active |
| Timers | 4 x 8/16-bit |
| PWM Outputs | Up to 5 (CCP + ECCP) |
| Communication | 1x I2C, 1x SPI, 1x USART (IrDA) |
| Package | 44-pin TQFP (PT), 10x10 mm |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial) |
| I/O Pins | 36 |
| RoHS Status | Compliant |
PIC18LF4685-I/PT Pin Configuration
| Pin 1 | MCLR — Master Clear (Reset) input |
| Pin 2 | RA0/AN0 — Port A bit 0 / Analog input 0 |
| Pin 3 | RA1/AN1 — Port A bit 1 / Analog input 1 |
| Pin 4 | RA2/AN2/VREF- — Port A bit 2 / Analog input 2 / ADC VREF- |
| Pin 5 | RA3/AN3/VREF+ — Port A bit 3 / Analog input 3 / ADC VREF+ |
| Pin 6 | RA4/T0CKI — Port A bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4 — Port A bit 5 / Analog input 4 |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKI — Crystal oscillator input / external clock input |
| Pin 10 | OSC2/CLKO — Crystal oscillator output / clock output |
| Pin 11 | RC0/T1OSO/T1CKI — Port C bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 12 | RC1/T1OSI — Port C bit 1 / Timer1 oscillator input |
| Pin 13 | RC2/CCP1 — Port C bit 2 / Capture/Compare/PWM 1 |
| Pin 14 | RC3/SCK/SCL — Port C bit 3 / SPI clock / I2C clock |
| Pin 15 | RC4/SDI/SDA — Port C bit 4 / SPI data in / I2C data |
| Pin 16 | RC5/SDO — Port C bit 5 / SPI data out |
| Pin 17 | RC6/TX/CK — Port C bit 6 / USART async transmit / clock |
| Pin 18 | RC7/RX/DT — Port C bit 7 / USART async receive / data |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage |
| Pin 21 | RB0/INT0 — Port B bit 0 / External interrupt 0 |
| Pin 22 | RB1/INT1 — Port B bit 1 / External interrupt 1 |
| Pin 23 | RB2/INT2 — Port B bit 2 / External interrupt 2 |
| Pin 24 | RB3/INT3 — Port B bit 3 / External interrupt 3 |
| Pin 25 | RB4 — Port B bit 4 |
| Pin 26 | RB5 — Port B bit 5 |
| Pin 27 | RB6/PGC — Port B bit 6 / ICSP clock |
| Pin 28 | RB7/PGD — Port B bit 7 / ICSP data |
| Pin 29 | CANTX — ECAN transmit output |
| Pin 30 | CANRX — ECAN receive input |
| Pin 31 | RE0/RD — Port E bit 0 / Parallel port read |
| Pin 32 | RE1/WR — Port E bit 1 / Parallel port write |
| Pin 33 | RE2/CS — Port E bit 2 / Parallel port chip select |
| Pin 34 | VDD — Positive supply voltage |
| Pin 35 | VSS — Ground reference |
| Pin 36 | RD0/PSP0 — Port D bit 0 / Parallel slave port bit 0 |
| Pin 37 | RD1/PSP1 — Port D bit 1 / Parallel slave port bit 1 |
| Pin 38 | RD2/PSP2 — Port D bit 2 / Parallel slave port bit 2 |
| Pin 39 | RD3/PSP3 — Port D bit 3 / Parallel slave port bit 3 |
| Pin 40 | RD4/PSP4 — Port D bit 4 / Parallel slave port bit 4 |
| Pin 41 | RD5/PSP5 — Port D bit 5 / Parallel slave port bit 5 |
| Pin 42 | RD6/PSP6 — Port D bit 6 / Parallel slave port bit 6 |
| Pin 43 | RD7/PSP7 — Port D bit 7 / Parallel slave port bit 7 |
| Pin 44 | AVDD — Analog positive supply |
Typical Applications
PIC18LF4685-I/PT is suitable for 6 applications: Automotive Body and Powertrain ECU, Industrial Sensor and CAN Node, BLDC Motor Controller, HVAC Climate Control System, Medical Monitoring Peripheral, OBD-II Vehicle Diagnostic Interface.
Automotive Body and Powertrain ECU
The PIC18LF4685-I/PT fits automotive body and powertrain ECUs because of its integrated ECAN 2.0B module supporting both 11-bit and 29-bit identifiers at up to 1 Mbaud bus rates, plus its 2.0V-5.5V operating range tolerant to cranking transients. Its 96KB Flash comfortably stores communication stacks (CANopen, J1939) plus application logic, while the 10-bit ADC with 13 channels reads multiple sensor inputs simultaneously. Place the MCU on a CAN segment terminated with 120-ohm resistors at each end; the on-chip acceptance filters reduce host CPU load by rejecting non-matching IDs in hardware.
Recommended
Industrial Sensor and CAN Node
For industrial sensor nodes on a CANopen or DeviceNet backbone, the PIC18LF4685-I/PT provides deterministic CAN messaging via its ECAN hardware acceptance filters and 16-bit time-stamping from Timer 2/5. The 96KB Flash hosts full CANopen stack plus sensor calibration tables, while nanoWatt technology reduces quiescent current below 1 uA in Sleep mode for 4-20 mA loop-powered designs. Connect the MCU to a 24V industrial bus through an isolated DC-DC converter and an MCP2551 CAN transceiver; decouple VDD with 100 nF X7R ceramic capacitors placed within 5 mm of the pins.
Recommended
BLDC Motor Controller
The PIC18LF4685-I/PT drives small BLDC motors via its Enhanced CCP (ECCP) peripheral generating complementary PWM with programmable dead-band, plus 5 PWM channels for three-phase inverter control. Its 10 MIPS performance at 40 MHz handles field-oriented control loops at 10 kHz switching frequency with margin for current sensing via the 10-bit ADC. Pair the MCU with gate drivers such as the MCP8024 and three-phase inverter FETs; current feedback through dedicated ADC channels completes the closed-loop vector control implementation.
Recommended
HVAC Climate Control System
The PIC18LF4685-I/PT is well-suited to HVAC climate control panels where multiple temperature sensors, fan-speed control, and a CAN interface to the building automation network are required. Its 13-channel 10-bit ADC reads NTC thermistor arrays for zone temperature, while PWM outputs drive triac-gated fan motors. The 96KB Flash accommodates user-interface state machines, scheduling, and PID control loops without external memory. The 2.0V-5.5V range allows operation from 24VAC rectified supplies via simple linear regulation.
Recommended
Medical Monitoring Peripheral
For non-implantable medical peripherals such as bedside patient monitors and infusion pump controllers, the PIC18LF4685-I/PT provides reliable CAN connectivity for inter-device coordination plus 10-bit ADC for sensor readout. Its industrial temperature grade (-40C to +85C) suits clinical environments, and the wide 2.0V-5.5V range supports battery-backed operation. The MCU does not meet IEC 60601-1 isolation or AEC-Q100, so use it only in non-safety-critical subsystems paired with a higher-grade supervisory MCU.
Recommended
OBD-II Vehicle Diagnostic Interface
The PIC18LF4685-I/PT serves as the core of an OBD-II diagnostic dongle, decoding CAN and ISO 9141-2 traffic from the vehicle bus and relaying data to a smartphone via UART or Bluetooth. Its ECAN module handles 500 kbaud high-speed CAN natively, while the USART supports K-line and L-line ISO 9141 communication. The 96KB Flash holds OBD-II PID tables, and the 3.25KB RAM buffers decoded messages. Power the MCU from the vehicle 12V rail through a 5V LDO such as the MCP1700.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF4685-I/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4685-I/PT | PIC18LF4685T-I/PT | PIC18LF4680-I/PT | PIC18LF45K80-I/PT | PIC18LF4585-I/PT |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-pin TQFP (PT) | 44-pin TQFP (PT) - same | 44-pin TQFP (PT) - same | 44-pin TQFP (PT) - same | 44-pin TQFP (PT) - same | 44-pin TQFP (PT) - same |
| Program Memory (Flash) | 96 KB | 96 KB | 96 KB | 64 KB | 32 KB | 48 KB |
| RAM | 3.25 KB | 3.25 KB | 3.25 KB | 3.25 KB | 3.6 KB | 3.25 KB |
| Operating Voltage | 2.0V to 5.5V | 4.2V to 5.5V | 2.0V to 5.5V | 2.0V to 5.5V | 1.8V to 3.6V | 2.0V to 5.5V |
| ECAN Module | Yes (CAN 2.0B active) | Yes (CAN 2.0B active) | Yes (CAN 2.0B active) | Yes (CAN 2.0B active) | Yes (ECAN) | No |
| ADC Resolution | 10-bit | 10-bit | 10-bit | 10-bit | 12-bit | 10-bit |
| AEC-Q100 Automotive Qualified | No | Yes (5V variant) | No | No | No | No |
Key Differentiators
- Integrated ECAN 2.0B module with 6 acceptance filters (vs PIC18LF4585-I/PT)
- 96KB Flash vs 64KB on PIC18LF4680 (vs PIC18LF4680-I/PT)
- Wide 2.0V-5.5V operating voltage (vs PIC18F4685-I/PT)
Design Notes
Decouple each VDD pin with a 100 nF X7R ceramic capacitor placed within 5 mm of the pin. Add a single 10 uF tantalum or aluminum polymer bulk capacitor at the board's power entry point. The PIC18LF4685-I/PT can operate from 2.0V to 5.5V; for designs supplied from 12V or 24V rails, use an LDO such as MCP1700 (3.3V) or MCP1825 (5V) with adequate input voltage headroom. AVdd and Vdd should be tied together at the MCU, but a ferrite bead or small resistor between them is recommended if analog and digital sections are physically separated on the PCB.
Place the 40 MHz crystal or external oscillator within 5 mm of the OSC1/OSC2 pins, with a clean ground return path. Keep CANH and CANL traces as a differential pair with 120-ohm differential impedance and 120-ohm termination resistors at each end of the bus. Keep the ECAN traces away from high-current switching nodes (MOSFETs, motor phases) and route them over an unbroken ground plane. The MCLR pin should be tied to VDD through a 10 kohm resistor with a 100 nF decoupling capacitor to ground for noise immunity.
Do not exceed the absolute maximum VDD of 7.0V (recommended max 5.5V) or latch-up may occur. The LF prefix denotes 2.0V-5.5V operation; using a non-LF PIC18F4685 at 3.3V will fail to start reliably. When migrating from PIC18F4685 to PIC18LF4685, verify any code that depends on internal bandgap reference voltage at specific operating points. The ECAN module requires both CANTX and CANRX pins to be configured as digital inputs; leaving them analog will silently disable CAN. Always read-back configured CAN register values after initialization to confirm successful hardware handshake with the MCP2551 or equivalent transceiver.
Compliance Information
RoHS and REACH compliant per Microchip product declaration. Pb-free matte-tin finish. Not AEC-Q100 qualified - choose PIC18F4685-I/PT 5V automotive variant or a K-series part for automotive safety applications.