PIC18F4320-I/P - 8-Bit 40MHz 8KB Flash MCU 40-PDIP | Microchip
MPN: PIC18F4320-I/P ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.3 | $6.30 |
| 10 | $5.75 | $57.50 |
| 100 | $5.2 | $520.00 |
| 500 | $4.6 | $2,300.00 |
| 1,000 | $4.05 | $4,050.00 |
PIC18F4320-I/P Overview
What is a PIC microcontroller? A Microcontroller Unit (MCU) is a single-chip computer that integrates a CPU core, program memory, working RAM, non-volatile storage, and a rich set of peripherals (ADC, timers, communications, comparators). PIC microcontrollers from Microchip use a Harvard RISC architecture that separates program and data buses, allowing simultaneous fetch and execute of instructions and producing deterministic interrupt latency that is widely favored in real-time control. The PIC18 series extends PIC16 code with 16-bit instructions, linear memory, and C-compiler friendly extensions that simplify firmware development using MPLAB XC8 and the free MPLAB IDE toolchain.
Key features include 256 bytes of EEPROM, self-programming capability for in-application firmware updates, an ICD (In-Circuit Debugger) interface, two CCP modules for capture/compare/PWM, a 10-bit Analog-to-Digital Converter with up to 13 input channels, two analog comparators, and a Master Synchronous Serial Port configurable as 3-wire SPI or 2-wire I2C. The nanoWatt Technology power-management suite provides multiple idle and sleep modes that drop run currents below typical values for battery-friendly designs. With 36 digital I/O on the 40-pin variant, the PIC18F4320-I/P delivers a higher pin density than the 28-pin members of the family while sharing the same PIC18 core, peripheral set, and toolchain.
Architecturally the device uses an enhanced 8-bit CPU with 77 single-word instructions, hardware multiplier, and prioritized interrupts with shadow registers. Memory is organized as a 16-bit-wide program Flash accessed through a 21-bit PC, plus 16-bit-wide file-register SRAM. Brown-out Reset, Watchdog Timer with its own on-chip RC oscillator, and a wide operating-voltage range protect against supply glitches and code runaway in unattended installations.
Typical applications include industrial automation and process control nodes, sensor signal conditioning with the 10-bit ADC, motor control using CCP PWM outputs, automotive body and interior subsystems on 12 V buses (down-regulated), low-power remote sensor platforms, educational and hobbyist development boards, and USB/serial bridge firmware for legacy serial peripherals. The through-hole 40-pin PDIP is also widely used in breadboard prototyping and educational labs where SOIC/QFN parts are inconvenient.
A key design consideration is that the PIC18F4320 family is mature and the -I/P variant is preferred over the -E/P extended-temperature variant for industrial-cost applications; for newer designs with more memory or peripherals, Microchip recommends the PIC18F46K22, PIC18F46K40, or PIC18F46Q10 families, which are software-compatible and pin-compatible in many cases while consuming less power and adding PPS (Peripheral Pin Select).
This page synthesizes distributor pricing, drop-in PIC18F-family alternatives, and practical design notes drawn from Microchip datasheet DS39582B and the PIC18F4320 product page.
Drop-in alternatives for PIC18F4320-I/P — 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/P (same form factor and footprint) — differing in Package, Operating Temperature, ADC, Timers, Program Memory (Flash).
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F4520-I/P
✅ Drop-In✓ In Stock
$5.35 / Unit
View Datasheet →PIC18F4420-I/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F4620-I/P
✅ Drop-In✓ In Stock
$5.08 / Unit
View Datasheet →PIC18F46K22-I/P
✅ Drop-In✓ In Stock
$2.61 / Unit
View Datasheet →PIC18F46K40-I/P
✅ Drop-In✓ In Stock
$2.4 / Unit
View Datasheet →PIC18F4220-I/P
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$4.78 / Unit
View Datasheet →PIC18F4320-I/P Maximum Ratings & Electrical Characteristics
| Core | PIC18 (8-bit RISC, Harvard) |
| CPU Instruction Set | 77 single-word instructions |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Program Memory (Flash) | 8 KB (4K x 16) |
| Data SRAM | 512 bytes |
| Data EEPROM | 256 bytes |
| Operating Voltage Range | 2.0 V to 5.5 V |
| Digital I/O Pins | 36 |
| A/D Converter | 10-bit, up to 13 channels |
| Comparators | 2 analog comparators |
| CCP / PWM Modules | 2 CCP |
| Communication | MSSP (SPI/I2C), USART |
| Timers | 4 (Timer0/1/2/3) |
| Self-Programming | Yes |
| In-Circuit Debug | ICD |
| Brown-out Reset / WDT | Yes / Yes |
| Operating Temperature | -40 C to +85 C (Industrial, I suffix) |
| Package | 40-pin PDIP (0.600 in / 15.24 mm) |
| Mounting Type | Through-Hole |
| MSL Level | 1 (not moisture-sensitive for PDIP) |
| RoHS Status | Compliant |
PIC18F4320-I/P Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (Reset) input or programming voltage |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input 1 |
| Pin 4 | RA2/AN2/VREF- — PORTA bit 2 / Analog input 2 / ADC VREF- |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input 3 / ADC VREF+ |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / Analog input 4 / SPI Slave Select |
| Pin 8 | OSC1/CLKI — Oscillator crystal input / external clock in |
| Pin 9 | OSC2/CLKO — Oscillator crystal output / clock out |
| Pin 10 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock |
| Pin 11 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator in / CCP2 |
| Pin 12 | RC2/CCP1 — PORTC bit 2 / CCP1 (PWM output) |
| Pin 13 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 14 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 15 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 16 | RC6/TX/CK — PORTC bit 6 / USART TX / USART clock |
| Pin 17 | RC7/RX/DT — PORTC bit 7 / USART RX / USART data |
| Pin 18 | VSS — Ground |
| Pin 19 | VDD — Positive supply (+2.0 V to +5.5 V) |
| Pin 20 | RB0/INT0 — PORTB bit 0 / External interrupt 0 |
| Pin 21 | RB1/INT1 — PORTB bit 1 / External interrupt 1 |
| Pin 22 | RB2/INT2 — PORTB bit 2 / External interrupt 2 |
| Pin 23 | RB3/CCP2 — PORTB bit 3 / CCP2 (alternate) |
| Pin 24 | RB4 — PORTB bit 4 (interrupt-on-change) |
| Pin 25 | RB5 — PORTB bit 5 (interrupt-on-change) |
| Pin 26 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 27 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 28 | RE0/RD/AN5 — PORTE bit 0 / parallel slave read / Analog input 5 |
| Pin 29 | RE1/WR/AN6 — PORTE bit 1 / parallel slave write / Analog input 6 |
| Pin 30 | RE2/CS/AN7 — PORTE bit 2 / parallel slave chip select / Analog input 7 |
| Pin 31 | VDD — Positive supply (second VDD pin) |
| Pin 32 | VSS — Ground (second VSS pin) |
| Pin 33 | RA6 — PORTA bit 6 |
| Pin 34 | RA7 — PORTA bit 7 |
| Pin 35 | RC0 — PORTC bit 0 (second function) |
| Pin 36 | RC1 — PORTC bit 1 (second function) |
| Pin 37 | RC2 — PORTC bit 2 (second function) |
| Pin 38 | RC3 — PORTC bit 3 (second function) |
| Pin 39 | RC4 — PORTC bit 4 (second function) |
| Pin 40 | RC5 — PORTC bit 5 (second function) |
Typical Applications
PIC18F4320-I/P is suitable for 6 applications: Industrial Process Control Nodes, Sensor Signal Conditioning with 10-bit ADC, Motor Control with CCP PWM, Battery-Backed Remote Sensor Platforms, Educational and Hobbyist Development Boards, USB/Serial Bridge Firmware.
Industrial Process Control Nodes
The PIC18F4320-I/P fits industrial process-control nodes because its 36 digital I/O on the 40-pin PDIP allow direct wiring of limit-switch inputs, relay-driver outputs, and panel-indicator LEDs without external multiplexers. The 13-channel 10-bit ADC delivers ~4.88 mV LSB at 5 V full-scale, sufficient for 4-20 mA loop sense resistors scaled by 250 ohm shunts and thermistor/PT1000 temperature bridges. Its industrial -40C to +85C temperature range and 2.0-5.5 V supply permit direct operation from 24 V industrial rails down-regulated to 5 V. The CCP modules generate PWM for proportional valve control, and the nanoWatt sleep modes let battery-backed nodes sleep below 1 uA between supervisor scans.
Recommended
Sensor Signal Conditioning with 10-bit ADC
The PIC18F4320-I/P's 13-channel 10-bit ADC makes it well suited for multi-sensor data-acquisition front ends where each channel digitizes a different transducer (temperature, light, strain, potentiometer). At 5 V VDD the 10-bit resolution yields ~4.88 mV per LSB, adequate for bridge sensors after op-amp gain and for thermistor voltage dividers across 0-70C spans. Acquisition-time and conversion-clock registers (ADCON2) are user-programmable, so designers can trade conversion speed for noise immunity via longer acquisition. The MSSP peripheral streams converted samples over SPI to a host MCU, while the USART offers RS-232/RS-485 wired link as a lower-cost alternative.
Recommended
Motor Control with CCP PWM
The PIC18F4320-I/P drives brushed DC and small stepper motors using its two CCP modules, which generate 10-bit PWM with programmable frequency, duty cycle, and dead-band control via the PWM steering mode. At 40 MHz the PWM resolution reaches ~10 bits at 39 kHz carrier, suitable for sub-100 W brushed-H-bridge drives and unipolar stepper coils. The 36 I/O include dedicated PWM output pins, direction-control GPIOs, and analog feedback channels for current sensing via the on-chip comparators. Hardware fault inputs trip the PWM output within a single instruction cycle, providing safe shutdown without software latency.
Recommended
Battery-Backed Remote Sensor Platforms
The PIC18F4320-I/P suits battery-backed remote sensors thanks to its nanoWatt Technology suite: Idle, Sleep, and the ultra-low-power Timer1 oscillator mode drop quiescent quiescent current to sub-1 uA while still waking on interrupt or WDT. Operating from 2.0 V to 5.5 V, it runs directly from two alkaline cells (3 V nominal) or a single Li-ion cell (3.7 V), with the internal brown-out reset protecting against battery end-of-life. The 10-bit ADC with internal 1.2 V bandgap reference enables direct battery-voltage monitoring without external divider components in low-power modes. Self-programming Flash lets the same node receive OTA firmware updates over SPI/UART.
Recommended
Educational and Hobbyist Development Boards
The PIC18F4320-I/P is widely used in educational labs and hobbyist projects because its 40-pin PDIP through-hole form factor drops directly into breadboards and 0.600 inch DIP sockets - a key advantage over QFN/SOIC packages that require reflow or breakout boards. The on-chip ICD interface allows students to single-step and inspect registers using Microchip's free MPLAB X IDE and PICkit 3/5 programmers, with no external debug-header circuitry required. The 77-instruction PIC18 instruction set, C-friendly architecture, and abundant free XC8 compiler resources make the part a staple of undergraduate embedded-systems curricula. Self-programming lets students bootload bootloader code from the same ICSP pins.
Recommended
USB/Serial Bridge Firmware
The PIC18F4320-I/P can host legacy serial-bridge firmware converting between RS-232/RS-485 UART traffic and TTL SPI/I2C peripherals, using its MSSP (SPI/I2C) module plus USART. The 8 KB Flash fits common bridge command sets, and the 36 I/O provide enough pins to expose multiple chip-select lines and status LEDs. At 40 MHz the USART sustains 115200 baud reliably with low interrupt overhead. Industrial temperature range and 5.5 V tolerance simplify connection to legacy 5 V equipment in factory-floor retrofits where modern USB-native MCUs are not acceptable.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F4320-I/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4520-I/P | PIC18F4420-I/P | PIC18F4620-I/P | PIC18F46K22-I/P | PIC18F46K40-I/P | PIC18F4220-I/P |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 40-pin PDIP | 40-pin PDIP - same | 40-pin PDIP - same | 40-pin PDIP - same | 40-pin PDIP - same | 40-pin PDIP - same | 40-pin PDIP - same |
| Program Flash | 8 KB | 32 KB | 16 KB | 64 KB | 64 KB | 64 KB | 4 KB |
| Data SRAM | 512 bytes | 1.5 KB | 768 bytes | 3.96 KB | 3.86 KB | 3.6 KB | 512 bytes |
| EEPROM | 256 bytes | 256 bytes | 256 bytes | 1 KB | 1 KB | 1 KB | 256 bytes |
| Maximum CPU Speed | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 64 MHz / 16 MIPS | 64 MHz / 16 MIPS | 40 MHz / 10 MIPS |
| ADC Channels | 13 channels x 10-bit | 13 channels x 10-bit | 13 channels x 10-bit | 13 channels x 10-bit | 28 channels x 10-bit | 35 channels x 10-bit | 13 channels x 10-bit |
| Operating Voltage | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 2.0 V to 5.5 V |
| PPS (Peripheral Pin Select) | No | No | No | No | Yes | Yes | No |
| Lifecycle Status | Active | Active | Active | Active | Active | Active | Active |
Key Differentiators
- 40-pin PDIP with 36 I/O in the PIC18F4x20 family (vs PIC18F2520-I/SP (28-pin SPDIP))
- Industrial temperature grade at standard pricing (vs PIC18F4320-E/P (extended temperature))
- Mature 10 MIPS PIC18 core with extensive tooling (vs Newer PIC18F46K40-I/P (16 MIPS with PPS))
Design Notes
Estimated: at 40 MHz and 5 V VDD, PIC18F4320 typical run current is approximately 11-15 mA per Microchip datasheet DS39582B. The dual VDD pins (19 and 31) MUST both be connected, and the dual VSS pins (18 and 32) MUST both be connected, to avoid voltage bounce that causes ADC noise and brown-out misfires. Place a 100 nF decoupling cap within 5 mm of each VDD pin and a single 10 uF bulk cap on the supply rail. For sleep-mode designs, configure the WDT postscaler to extend wake intervals while keeping Timer1 running from its 32 kHz crystal for timekeeping below 1 uA.
The 40-pin PDIP footprint gives generous room for hand routing on 2-layer PCBs but engineers frequently mis-route ICSP pins: MCLR/VPP (pin 1) needs a 10 kohm pull-up to VDD plus a programming header tap to VPP, while PGC (pin 26) and PGD (pin 27) must be reserved for the in-circuit debugger and not loaded with significant capacitance (>50 pF total). The 36 I/O are split across PORTA/PORTB/PORTC/PORTE; ensure ADC inputs AN0-AN13 are kept away from switching nodes to avoid digital-coupling noise on ADC readings, per Microchip datasheet DS39582B section 16.0 'Analog-to-Digital Converter'.
Do not assume the PIC18F4320 and PIC18F4321 are pin-compatible - they belong to different family branches and PIC18F4321 introduces PPS register re-mapping. Always verify against the datasheet DS39582B pinout when migrating firmware across PIC18F43xx variants. Do not exceed 5.5 V on any pin including MCLR during in-circuit programming (ICSP high-voltage mode). Finally, do not drive the 36 I/O above source/sink limits (25 mA per pin, 200 mA per port per Microchip datasheet DS39582B), and ensure external pull-ups on I2C lines use 4.7 kohm or smaller values because the MSSP I/O are not true open-drain on this family.
Compliance Information
RoHS compliant per Microchip product page. Industrial temperature grade (-40C to +85C) is standard; -E/P extended variant exists for +125C but is not automotive AEC-Q100 qualified. Halogen-free status not explicitly stated in the verified data - default to 'unknown'.
