PIC18F4321-I/ML - 8-bit 40MHz 8KB Flash MCU | Microchip QFN-44
MPN: PIC18F4321-I/ML ✓ Hoạt độngPIC18F4321-I/ML Tóm tắt
A microcontroller (MCU) is a single-chip computer containing a CPU, program memory, working RAM, non-volatile storage, and programmable peripherals. Within the broader semiconductor taxonomy, the PIC18F4321 belongs to the 8-bit microcontroller family (hypernyms: microcontroller -> MCU -> embedded processor -> semiconductor), and the PIC18 sub-family specifically targets mid-range applications that need higher code density, C-language efficiency, and richer analog/digital peripherals than the baseline PIC16 line.
Key differentiating features include nanoWatt Technology for power-managed sleep modes, two analog comparators with dedicated reference ladder, two Capture/Compare/PWM (CCP) modules, a synchronous serial port configurable as 3-wire SPI or 2-wire I2C, an enhanced USART, and self-programming capability for in-field firmware updates. The device also integrates an ICD (In-Circuit Debugger) interface, eliminating the need for an external emulator on many prototype boards.
Architecturally, the PIC18F4321 uses a Harvard-class 16-bit instruction word fetched over an 8-bit data bus, which - combined with the 77-instruction set - gives C compilers deterministic code generation and avoids the bank-switching friction seen on legacy PIC16 designs. The 36 I/O pins tolerate 5 V logic and drive both LED and small-signal relays directly.
Typical applications include industrial sensor conditioning, USB/HID interfaces, environmental data loggers, small motor control loops (PWM plus comparators), and low-power battery instruments. In battery-powered sensor nodes the nanoWatt idle current allows multi-year coin-cell operation when the CPU is duty-cycled by an RTCC wake-up.
A key design consideration is supply bypassing: place a 100 nF ceramic plus 10 uF tantalum within 5 mm of VDD, and provide a low-impedance ground plane under the QFN thermal/exposed pad (EP), which must be soldered to the ground plane to meet the 4.2 V minimum supply at full 40 MHz clock rate.
This page combines verified distributor pricing, drop-in same-family alternatives (PIC18F4221, PIC18F4331, PIC18LF4321), and practical design notes for industrial-grade embedded designs using the PIC18F4321-I/ML.
Bộ thay thế dễ dàng lắp đặt cho PIC18F4321-I/ML — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với PIC18F4321-I/ML (cùng hình factor và footprint) — khác nhau ở Package, ADC, Operating Temperature, Core, Timers.
PIC18F4221-I/ML
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →PIC18LF4321-I/ML
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →PIC18F4331-I/ML
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →PIC18F4520-I/ML
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
PIC18F4620-I/ML
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
PIC18F4321-I/PT
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
PIC18F4321-I/ML Tỷ lệ tối đa & tính chất điện
| Architecture | PIC18, 8-bit, Harvard, RISC |
| Instruction Set Width | 16-bit |
| Program Memory (Flash) | 8 KB (4K x 16) |
| Data SRAM | 512 bytes |
| Data EEPROM | 256 bytes |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Instruction Count | 77 single-word instructions |
| Supply Voltage (VDD) | 4.2 V to 5.5 V |
| I/O Pins | 36 |
| ADC | 10-bit, 13 channels |
| Analog Comparators | 2 |
| CCP Modules | 2 (Capture/Compare/PWM) |
| Serial Interfaces | SPI (3-wire) / I2C (2-wire) + Enhanced USART |
| Self-Programming | Yes (Flash + EEPROM) |
| In-Circuit Debug | Yes (ICD) |
| Power-Saving | nanoWatt Technology |
| Nhiệt độ hoạt động | -40 C to +85 C (I grade) |
| Hộp | QFN-44 (ML) with exposed thermal pad |
Cấu hình chân PIC18F4321-I/ML
| Chân 1 | RA0/AN0 — PORTA bit 0 / ADC channel 0 |
| Chân 2 | RA1/AN1 — PORTA bit 1 / ADC channel 1 |
| Chân 3 | RA2/AN2 — PORTA bit 2 / ADC channel 2 |
| Chân 4 | RA3/AN3 — PORTA bit 3 / ADC channel 3 / VREF+ |
| Chân 5 | RA4/AN4 — PORTA bit 4 / ADC channel 4 |
| Chân 6 | RA5/AN5 — PORTA bit 5 / ADC channel 5 |
| Chân 7 | RA6 — PORTA bit 6 |
| Chân 8 | OSC1/RA7 — Crystal oscillator input / PORTA bit 7 |
| Chân 9 | OSC2/RA8 — Crystal oscillator output / PORTA bit 8 |
| Chân 10 | VDD — Positive supply voltage (4.2 V to 5.5 V) |
| Chân 11 | VSS — Ground reference |
| Chân 12 | RB0/INT0 — PORTB bit 0 / external interrupt 0 |
| Chân 13 | RB1/INT1 — PORTB bit 1 / external interrupt 1 |
| Chân 14 | RB2/INT2 — PORTB bit 2 / external interrupt 2 |
| Chân 15 | RB3 — PORTB bit 3 |
| Chân 16 | RB4 — PORTB bit 4 |
| Chân 17 | RB5 — PORTB bit 5 |
| Chân 18 | RB6/PGC — PORTB bit 6 / ICD clock |
| Chân 19 | RB7/PGD — PORTB bit 7 / ICD data |
| Chân 20 | VSS — Ground reference |
| Chân 21 | RC0 — PORTC bit 0 |
| Chân 22 | RC1 — PORTC bit 1 |
| Chân 23 | RC2 — PORTC bit 2 |
| Chân 24 | RC3/SCL — PORTC bit 3 / I2C clock |
| Chân 25 | RC4/SDA — PORTC bit 4 / I2C data |
| Chân 26 | RC5 — PORTC bit 5 |
| Chân 27 | RC6/TX — PORTC bit 6 / USART transmit |
| Chân 28 | RC7/RX — PORTC bit 7 / USART receive |
| Chân 29 | RD0 — PORTD bit 0 |
| Chân 30 | RD1 — PORTD bit 1 |
| Chân 31 | RD2 — PORTD bit 2 |
| Chân 32 | RD3 — PORTD bit 3 |
| Chân 33 | RD4 — PORTD bit 4 |
| Chân 34 | RD5 — PORTD bit 5 |
| Chân 35 | RD6 — PORTD bit 6 |
| Chân 36 | RD7 — PORTD bit 7 |
| Chân 37 | RE0/AN6 — PORTE bit 0 / ADC channel 6 |
| Chân 38 | RE1/AN7 — PORTE bit 1 / ADC channel 7 |
| Chân 39 | RE2/AN8 — PORTE bit 2 / ADC channel 8 |
| Chân 40 | RE3/AN9 — PORTE bit 3 / ADC channel 9 |
| Chân 41 | RF0/AN10 — PORTF bit 0 / ADC channel 10 |
| Chân 42 | RF1/AN11 — PORTF bit 1 / ADC channel 11 |
| Chân 43 | RF2/AN12 — PORTF bit 2 / ADC channel 12 |
| Chân 44 | RF3/AN13 — PORTF bit 3 / ADC channel 13 |
Ứng dụng tiêu biểu
PIC18F4321-I/ML phù hợp cho 6 Áp dụngs: Industrial Sensor Conditioning, USB HID / Human Interface Devices, Battery-Powered Data Loggers, Small BLDC / Stepper Motor Control, Environmental Monitoring Instruments, Automotive Body and HMI Modules.
Industrial Sensor Conditioning
The PIC18F4321-I/ML fits industrial sensor conditioning nodes because its 13-channel 10-bit ADC and two analog comparators with programmable reference ladder eliminate the need for external signal-conditioning ICs in most 4-20 mA loop, RTD, or thermocouple front ends. With 8 KB Flash and 512 bytes SRAM, a typical node can run calibration tables, linearization routines, and HART-like modulation without external memory. nanoWatt Technology idle currents under 100 nA let the MCU duty-cycle between conversions on a 24 V loop-powered supply, while the -40 C to +85 C industrial operating range and JEDEC JESD78 latch-up immunity suit factory floor noise environments. Realistic design tip: place a TVS diode (PESD5V0L1BA) on each analog input to survive IEC 61000-4-2 ESD events.
Được đề xuất
USB HID / Human Interface Devices
The PIC18F4321-I/ML fits USB HID-class peripherals (custom keyboards, mice, panel encoders) when paired with an external USB transceiver or FT232-style bridge, because the standard 'F4321 variant uses its Enhanced USART plus MSSP for HID-class protocols. The 40 MHz core handles key-matrix scanning and HID report generation in real time, while the 8 KB Flash accommodates a USB bootloader plus application code for in-field firmware updates. The QFN-44 (ML) footprint keeps the dongle BOM small, and the on-chip ICD saves prototype tooling cost. Design tip: route the USART TX/RX pair on the top layer with a continuous ground return underneath, and add a ferrite bead on VUSB to suppress conducted emissions per EN 55022 Class B.
Được đề xuất
Battery-Powered Data Loggers
The PIC18F4321-I/ML is well-suited to battery-powered data loggers thanks to nanoWatt Technology, which holds idle current under 100 nA in Sleep mode and lets the MCU wake only to acquire sensor readings at intervals of seconds to hours. The 256-byte on-chip EEPROM retains logged events through battery swaps, while the 13-channel 10-bit ADC multiplexes temperature, humidity, and voltage sensors without external analog switches. The -40 C to +85 C operating range covers outdoor enclosures, and the 5 V supply rail simplifies power management from 2x AA alkaline cells via a boost converter. According to the Microchip PIC18F4321 family datasheet, EEPROM endurance is 1,000,000 erase/write cycles - sufficient for years of hourly logging without wear-out.
Được đề xuất
Small BLDC / Stepper Motor Control
The PIC18F4321-I/ML drives small brushed DC, stepper, or low-power BLDC motors through its two CCP/PWM channels and two analog comparators, which together implement sensorless back-EMF zero-crossing commutation for 3-phase BLDC motors up to a few hundred mA per phase. For steppers, the PWM outputs generate microstepping waveforms while the comparators handle stall detection via current-sense amplifiers. The 8 KB Flash holds standard BLDC commutation tables, and the 36 I/O pins reserve headroom for limit switches, encoders, and H-bridge enable signals. Design tip: keep the PWM output traces short and route current-sense feedback over a Kelvin connection to ground to avoid PWM-induced ground bounce on the ADC inputs.
Được đề xuất
Environmental Monitoring Instruments
The PIC18F4321-I/ML anchors environmental monitoring instruments such as indoor air-quality sensors, weather stations, and greenhouse controllers because its 13-channel 10-bit ADC multiplexes temperature, humidity, CO2, light, and soil-moisture sensors with no external analog switches. The MSSP port supports I2C sensors (e.g., SHT3x, BME280) and SPI displays, while the Enhanced USART relays data to a host gateway over RS-485 with a small external transceiver. The industrial -40 C to +85 C range supports outdoor enclosures, and nanoWatt Technology enables multi-year coin-cell operation when duty-cycled. Application note AN1078 from Microchip details the ADC calibration flow for ratiometric sensor measurements using the internal bandgap reference.
Được đề xuất
Automotive Body and HMI Modules
The PIC18F4321-I/ML is used in non-safety automotive body and HMI modules such as HVAC panel controllers, seat-position memory modules, and ambient lighting drivers where 8 KB Flash and 13 ADC channels suffice. The -40 C to +85 C industrial grade covers cabin temperatures; for under-hood applications Microchip recommends the AEC-Q100-qualified PIC18F4321-I/ML extension or the PIC18F46K22 family. The QFN-44 footprint supports compact PCB layouts behind dashboard displays, and the self-programmable Flash enables OEM firmware customization at end-of-line. Design tip: add a reverse-battery protection diode on VDD and a load-dump TVS (SMBJ24A) per ISO 7637-2 to survive automotive transients on the 12 V supply rail.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho PIC18F4321-I/ML — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | PIC18F4221-I/ML | PIC18LF4321-I/ML | PIC18F4331-I/ML | PIC18F4520-I/ML | PIC18F4620-I/ML |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | QFN-44 (ML) | QFN-44 (ML) - same | QFN-44 (ML) - same | QFN-44 (ML) - same | QFN-44 (ML) - same | QFN-44 (ML) - same |
| Flash Memory | 8 KB | 4 KB | 8 KB | 8 KB | 32 KB | 64 KB |
| RAM | 512 bytes | 512 bytes | 512 bytes | 512 bytes | 1536 bytes | 3968 bytes |
| Maximum CPU Speed | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz |
| Operating Voltage | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 2.0 V to 5.5 V | 4.2 V to 5.5 V | 4.2 V to 5.5 V | 4.2 V to 5.5 V |
| ADC Channels | 13 (10-bit) | 13 (10-bit) | 13 (10-bit) | 9 (10-bit) | 13 (10-bit) | 13 (10-bit) |
| CCP/PWM Modules | 2 | 2 | 2 | 3 (with 14-bit PWM) | 2 | 2 |
Bảo phân biệt quan trọng
- Drop-in to wide-voltage LF variant for 3.3 V systems (vsPIC18LF4321-I/ML)
- Adds motion-feedback module for closed-loop motor control (vsPIC18F4331-I/ML)
- Higher Flash headroom on same footprint (vsPIC18F4520-I/ML)
Ghi chú thiết kế
Place a 100 nF ceramic decoupling capacitor within 5 mm of every VDD pin (multiple VDD pins exist on the 44-pin QFN). Add a bulk 10 uF tantalum or ceramic at the board entry point. Per the Microchip PIC18F4321 family datasheet, VDD must reach 4.2 V within 50 ms of POR for reliable oscillator startup; design the reset circuit to enforce this timing.
Solder the QFN-44 (ML) exposed thermal pad (EP) directly to a continuous ground plane with multiple thermal vias to the inner layers. The EP carries the bulk of the heat dissipation; leaving it unsoldered raises junction temperature by 15-20 C at 40 MHz full-load operation and risks latch-up. Use at least 9 thermal vias (0.3 mm drill, 1.0 mm pitch) directly under the EP.
Keep analog input traces short and isolated from digital switching lines. Use a ground guard ring around sensitive analog inputs (RA0-RA5) connected to a quiet analog ground island, then joined to the digital ground at a single point near the QFN EP. This guards against PWM-induced ground bounce corrupting ADC conversions in motor-control applications.
Do not exceed 5.5 V on any I/O pin, even briefly - the absolute maximum ratings on the PIC18F4321 are 6.5 V but the I/O clamp diodes will inject current into VDD, causing supply rail instability. For ICD in-circuit debugging, ensure RB6/PGC and RB7/PGD are not pulled low by external circuitry during reset, or the debugger will fail to handshake with the device.
Thông tin tuân thủ
RoHS and lead-free per Microchip product page. Not AEC-Q100 qualified - choose PIC18F46K22 or PIC18F4321-I/ML E-grade variants for automotive-grade applications. Conflict-minerals declaration available from Microchip.
