PIC18F4320-I/PT - 8KB Flash 8-bit MCU, 40MHz, 44-TQFP | Microchip
MPN: PIC18F4320-I/PT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.1 | $6.10 |
| 10 | $5.45 | $54.50 |
| 100 | $4.78 | $478.00 |
| 500 | $4.15 | $2,075.00 |
| 1,000 | $3.62 | $3,620.00 |
PIC18F4320-I/PT Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, memory, and peripherals around an 8-bit data bus. The PIC18 family is Microchip's high-performance 8-bit tier, sitting above the PIC16 baseline and PIC12/14 mid-range parts in computational throughput, and below the 16-bit PIC24/dsPIC families in arithmetic horsepower. Within the broader taxonomy, an 8-bit MCU belongs to microcontrollers -> embedded processors -> semiconductors. Compared with 32-bit ARM Cortex-M0 parts, 8-bit PIC MCUs offer lower unit cost, simpler toolchains, and deterministic interrupt latency, at the expense of raw compute and addressable memory. They remain the preferred choice for cost-sensitive, low-power, and peripheral-rich applications such as appliance control, sensor hubs, and human-interface panels.
The PIC18F4320 delivers up to 10 MIPS at 40 MHz from a 4.0-5.5V supply and includes enhanced peripherals such as a 10-bit ADC with up to 13 input channels, dual analog comparators with programmable reference, two CCP modules for PWM or capture/compare, an addressable USART, an MSSP configurable as SPI master/slave or I2C, and nanoWatt power-management features. It supports self-programming via ICSP and includes an ICD (In-Circuit Debug) interface, enabling in-field firmware updates and on-board debug without a special bondout package.
Typical applications for this device include industrial control panels, sensor signal conditioning, low-cost motor control via PWM, HVAC damper/valve actuators, appliance user-interface boards, and USB-to-UART bridges when paired with an external USB transceiver. The 36 I/O pins provide ample headroom for keypads, LEDs, character LCDs, and multiple sensor inputs in a single-chip design.
When designing with the PIC18F4320, verify that the 5V-tolerant I/O budget matches your sensor interface, and use the internal 8 MHz oscillator for cost-down designs that can tolerate +/-2% frequency accuracy. This page synthesizes distributor stock, drop-in PIC18 family alternatives, and application guidance not aggregated in any single manufacturer document.
Drop-in alternatives for PIC18F4320-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 PIC18F4320-I/PT (same form factor and footprint) — differing in Package, Core, Operating Temperature, ADC, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F4320T-I/PT
✅ Drop-In✓ In Stock
$3.1 / Unit
View Datasheet →PIC18F4320-E/PT
✅ Drop-In✓ In Stock
$4.2 / Unit
View Datasheet →PIC18LF4320-I/PT
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4520-I/PT
✅ Drop-In✓ In Stock
$4.05 / Unit
View Datasheet →PIC18F4320-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4620-I/PT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$5.45 / Unit
View Datasheet →PIC18F4580-I/PT
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18F4320-I/PT Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 (8-bit) |
| Program Memory (Flash) | 8 KB (4K x 16) |
| Data SRAM | 512 bytes |
| Data EEPROM | 256 bytes |
| Maximum CPU Frequency | 40 MHz (10 MIPS) |
| Supply Voltage (VDD) | 4.0 V to 5.5 V |
| I/O Pins | 36 |
| ADC | 10-bit, up to 13 channels |
| Analog Comparators | 2 |
| CCP/PWM Modules | 2 |
| Serial Interfaces | MSSP (SPI / I2C), USART (AUSART) |
| Timers | 4 (Timer0/1/2/3) |
| Operating Temperature | -40C to +85C (Industrial) |
| Package | 44-pin TQFP (10x10 mm) |
| Mounting Type | Surface Mount |
| Programming/Debug | ICSP + ICD |
| RoHS Status | Compliant |
PIC18F4320-I/PT Pin Configuration
| Pin 1 | RA2/AN2/VREF-/CVREF — PORTA bit 2 / Analog input 2 / DAC negative reference / comparator VREF output |
| Pin 2 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input 3 / DAC positive reference |
| Pin 3 | RA4/T0CKI/C1OUT — PORTA bit 4 / Timer0 clock input / Comparator 1 output |
| Pin 4 | RA5/AN4/SS/LVDIN — PORTA bit 5 / Analog input 4 / SPI slave select / LVD input |
| Pin 5 | OSC1/CLKI/RA7 — Crystal oscillator input / external clock input / PORTA bit 7 |
| Pin 6 | OSC2/CLKO/RA6 — Crystal oscillator output / clock output / PORTA bit 6 |
| Pin 7 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 8 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 PWM output |
| Pin 9 | RC2/CCP1 — PORTC bit 2 / CCP1 PWM output |
| Pin 10 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 11 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 12 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 13 | RC6/TX/CK — PORTC bit 6 / AUSART TX / AUSART clock |
| Pin 14 | RC7/RX/DT — PORTC bit 7 / AUSART RX / AUSART data |
| Pin 15 | VSS — Ground reference |
| Pin 16 | VDD — Positive supply (4.0-5.5V) |
| Pin 17 | RB0/AN12/INT0 — PORTB bit 0 / Analog input 12 / External interrupt 0 |
| Pin 18 | RB1/AN10/INT1 — PORTB bit 1 / Analog input 10 / External interrupt 1 |
| Pin 19 | RB2/AN8/INT2 — PORTB bit 2 / Analog input 8 / External interrupt 2 |
| Pin 20 | RB3/AN9/CCP2 — PORTB bit 3 / Analog input 9 / CCP2 alt |
| Pin 21 | RB4/AN11/KBI0 — PORTB bit 4 / Analog input 11 / Keyboard interrupt 0 |
| Pin 22 | RB5/KBI1/PGM — PORTB bit 5 / Keyboard interrupt 1 / LVP programming |
| Pin 23 | RB6/KBI2/PGC — PORTB bit 6 / Keyboard interrupt 2 / ICSP clock |
| Pin 24 | RB7/KBI3/PGD — PORTB bit 7 / Keyboard interrupt 3 / ICSP data |
| Pin 25 | VSS — Ground reference |
| Pin 26 | VDD — Positive supply (4.0-5.5V) |
| Pin 27 | RD0/PSP0 — PORTD bit 0 / Parallel slave port bit 0 |
| Pin 28 | RD1/PSP1 — PORTD bit 1 / Parallel slave port bit 1 |
| Pin 29 | RD2/PSP2 — PORTD bit 2 / Parallel slave port bit 2 |
| Pin 30 | RD3/PSP3 — PORTD bit 3 / Parallel slave port bit 3 |
| Pin 31 | RD4/PSP4 — PORTD bit 4 / Parallel slave port bit 4 |
| Pin 32 | RD5/PSP5 — PORTD bit 5 / Parallel slave port bit 5 |
| Pin 33 | RD6/PSP6/TX2 — PORTD bit 6 / Parallel slave port bit 6 / AUSART2 TX |
| Pin 34 | RD7/PSP7/RX2 — PORTD bit 7 / Parallel slave port bit 7 / AUSART2 RX |
| Pin 35 | VSS — Ground reference |
| Pin 36 | VDD — Positive supply (4.0-5.5V) |
| Pin 37 | RE0/RD/AN5 — PORTE bit 0 / Parallel slave port read / Analog input 5 |
| Pin 38 | RE1/WR/AN6 — PORTE bit 1 / Parallel slave port write / Analog input 6 |
| Pin 39 | RE2/CS/AN7 — PORTE bit 2 / Parallel slave port chip select / Analog input 7 |
| Pin 40 | AVSS — Analog ground |
| Pin 41 | AVDD — Analog positive supply |
| Pin 42 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 43 | RA1/AN1 — PORTA bit 1 / Analog input 1 |
| Pin 44 | VPP/MCLR/RE3 — Programming voltage / master clear reset / PORTE bit 3 |
Typical Applications
PIC18F4320-I/PT is suitable for 6 applications: Industrial Sensor Interface Board, HVAC Damper and Valve Actuator, Appliance User Interface Controller, USB-to-UART Bridge (paired), Low-Cost PWM Motor Speed Controller, Home Automation Sensor Hub.
Industrial Sensor Interface Board
The PIC18F4320-I/PT fits industrial sensor interface boards because its 13-channel 10-bit ADC and 2 analog comparators cover multiple analog inputs while the 36 digital I/O lines handle status LEDs, keypads, and isolated digital sensors on a single chip. Operating from 4.0-5.5V with industrial -40C to +85C temperature range, it drives 24V industrial logic via external level shifters while keeping firmware execution deterministic at 10 MIPS. The MSSP/SPI port reads digital sensors, and the AUSART links to an RS-485 transceiver for backhaul to a PLC. Designers save BOM cost by replacing an external ADC and comparator chip pair with on-chip equivalents while retaining ICSP debug for field service.
Recommended
HVAC Damper and Valve Actuator
The PIC18F4320-I/PT is a strong fit for HVAC damper and valve actuator designs thanks to its 2 CCP/PWM channels, which drive triac-controlled AC loads or DC motor H-bridges with hardware PWM. The 40 MHz core sustains closed-loop PID at the 1-2 kHz update rates typical of proportional actuators, while the 512-byte SRAM buffers sensor telemetry without overrunning the main loop. The 256-byte EEPROM stores calibration constants for valve stroke endpoints, surviving brownouts. The industrial -40C to +85C rating covers plenum and rooftop environments, and the 44-pin TQFP package offers enough I/O for end-stop sensors, current sense, and a Modbus/RS-485 link to the building automation system.
Recommended
Appliance User Interface Controller
In dishwasher, washing machine, and oven user-interface boards the PIC18F4320-I/PT drives multiplexed 7-segment displays, scans a 4x4 keypad matrix, and PWM-controls buzzer tones - all from one chip. Its 36 I/O lines handle the matrix, display segments, indicator LEDs, and relay drivers without external mux ICs, reducing BOM. The nanoWatt sleep modes drop quiescent current below 100 nA in standby, satisfying ENERGY STAR appliance standby requirements. ICSP and ICD debug speed development of the touchscreen replacement modules, and the 5V native operation lets the design switch relays directly without level translators.
Recommended
USB-to-UART Bridge (paired)
Although the PIC18F4320-I/PT lacks native USB, designers frequently pair it with an external USB-to-UART bridge such as the MCP2200 or MCP2221A to expose legacy UART peripherals over USB for firmware-update or diagnostic consoles. The AUSART on the PIC18F4320 speaks 3.3V TTL at standard baud rates up to 115.2 kbps, and the bridge handles enumeration and CDC-ACM on the host side. This keeps the firmware image small (only 8 KB) and avoids migrating to a USB-equipped MCU when USB is a one-off diagnostic interface rather than a primary product function.
Recommended
Low-Cost PWM Motor Speed Controller
The PIC18F4320-I/PT drives brushed DC and small BLDC motors through its two CCP/PWM modules with up to 10-bit PWM resolution at 40 kHz, sufficient for 24V brushed motors under 3 A. The 2 analog comparators provide hardware overcurrent and back-EMF detection with sub-microsecond latency, bypassing software sampling jitter. Its industrial temperature rating supports under-hood and workshop environments, while ICSP allows in-the-field firmware tuning of ramp profiles. With the 8 KB Flash, developers can store multiple acceleration profiles and select them at boot via external DIP switches.
Recommended
Home Automation Sensor Hub
The PIC18F4320-I/PT serves as the central MCU in a home-automation sensor hub that aggregates Zigbee or ThreadXLAN buckets via UART-attached radio modules, scans temperature/humidity/motion sensors, and forwards telemetry over Wi-Fi through an external ESP32 co-processor. Its 36 I/O lines multiplex I2C sensor buses via analog switches and read digital contact closures for door/window sensors. The 5V native I/O drives HVAC relay outputs without external drivers, while the 256-byte EEPROM stores network credentials and the last-known-good configuration. The industrial temperature grade supports basement and attic installations.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F4320-I/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4320T-I/PT | PIC18F4320-E/PT | PIC18LF4320-I/PT | PIC18F4520-I/PT | PIC18F4320-I/ML | PIC18F4620-I/PT | PIC18F4580-I/PT |
|---|---|---|---|---|---|---|---|---|
| Package | 44-pin TQFP (PT) 10x10 mm | 44-pin TQFP (PT) - same | 44-pin TQFP (PT) - same | 44-pin TQFP (PT) - same | 44-pin TQFP (PT) - same | 44-pin QFN (ML) | 44-pin TQFP (PT) - same | 44-pin TQFP (PT) - same |
| Brand | Microchip Technology | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same |
| Flash Memory | 8 KB | 8 KB (same) | 8 KB (same) | 8 KB (same) | 32 KB (+300%) | 8 KB (same) | 64 KB (+700%) | 32 KB (+300%) |
| Operating Voltage | 4.0-5.5 V | 4.0-5.5 V (same) | 4.0-5.5 V (same) | 2.0-5.5 V (lower) | 4.0-5.5 V (same) | 4.0-5.5 V (same) | 4.0-5.5 V (same) | 4.0-5.5 V (same) |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C (same) | -40C to +125C (Extended) | -40C to +85C (same) | -40C to +85C (same) | -40C to +85C (same) | -40C to +85C (same) | -40C to +85C (same) |
| ADC Channels | 13 channels | 13 (same) | 13 (same) | 13 (same) | 13 (same) | 13 (same) | 13 (same) | 11 (slightly fewer) |
| CCP/PWM Modules | 2 | 2 (same) | 2 (same) | 2 (same) | 2 (same) | 2 (same) | 2 (same) | 2 (same) |
| On-chip USB | No | No (same) | No (same) | No (same) | No (same) | No (same) | No (same) | No (same) |
| CAN Peripheral | No | No (same) | No (same) | No (same) | No (same) | No (same) | No (same) | Yes (CAN 2.0B) |
Key Differentiators
- 44-pin TQFP provides 36 I/O lines - more than typical 28-pin PIC18F2520 designs (vs PIC18F2520-I/SP)
- 13-channel 10-bit ADC with dual comparators is rare in this Flash tier (vs PIC18F4520-I/PT)
- Parallel Slave Port (PSP) on PORTD/PORTE for legacy bus expansion (vs PIC18F46J50-I/PT)
Design Notes
The PIC18F4320-I/PT requires a clean 5.0 V +/-10% supply on VDD (4.0-5.5V range). Decouple each VDD pin with a 100 nF X7R ceramic placed within 5 mm of the pin, plus a single 10 uF tantalum or aluminum-polymer bulk capacitor at the regulator output. Place the 10 uF bulk before the analog AVDD pin's LC filter (10 ohm + 100 nF) to prevent ADC reference noise. AVSS must connect to VSS at a single point under the MCU to avoid ground loops that inject ADC offset error.
Common PIC18F4320 design pitfalls: (1) Leave MCLR/VPP unbonded or driven by the PICkit ICSP programmer - never tie directly to VDD without a 10 kohm pull-up and diode, otherwise you lose In-Circuit Serial Programming. (2) Do not exceed the 8 MHz internal oscillator accuracy requirement if your timing budget is tight - use an external 20 MHz crystal with 22 pF caps for 40 MHz operation. (3) When using the parallel slave port (PSP), ensure RD7:RD0, RE0:RE2, and the RD/WR/CS strobes are initialized before PSPEN is asserted. (4) The MSSP module must be re-initialized when switching between SPI and I2C modes to avoid bus contention.
For 44-pin TQFP routing, break out all 36 I/O lines to header pads rather than to fine-pitch SMD-only fingers; this keeps prototype rework feasible with 0.1 inch headers. Route the analog AN0-AN12 signals in a guarded group on one PCB layer, with a GND guard ring around the analog traces. Keep crystal traces (OSC1/OSC2) under 10 mm length and surrounded by GND pour; the 40 MHz fundamental overtones couple to high-impedance analog inputs if traces run parallel.
Estimated: The PIC18F4320-I/PT consumes about 22 mA at 40 MHz with all peripherals active and IO sourcing 20 mA. With theta_JA around 50 C/W on a 4-layer JEDEC test board, junction temperature rise is roughly 1.1 C above ambient under typical 5V operation - well within the 85C industrial limit. However, when driving 36 outputs at 20 mA simultaneously (worst-case I/O load), supply current can climb to 100 mA and rise 5 C - derate by reducing I/O drive strength register bits when sourcing multiple LEDs.
Compliance Information
RoHS/REACH compliant per Microchip product page. Not AEC-Q100 qualified - for automotive use consider PIC18F4320-E/PT extended grade or migrate to PIC18F46K22 automotive family.