PIC18F2321-I/ML - 8-Bit PIC MCU, 40MHz, 8KB Flash 28-QFN | Microchip
MPN: PIC18F2321-I/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.95 | $4.95 |
| 10 | $4.45 | $44.50 |
| 100 | $3.96 | $396.00 |
| 500 | $3.56 | $1,780.00 |
| 1,000 | $3.17 | $3,170.00 |
PIC18F2321-I/ML Overview
An 8-bit microcontroller (MCU) is a small computer-on-a-chip built around an 8-bit data bus, executing instructions at a CPU register width of 8 bits. The PIC18F2321 belongs to the broader PIC18 family (Microchip PIC) within the hierarchy: 8-bit MCU -> microcontroller -> embedded controller -> semiconductor IC. Its RISC-based Harvard architecture, 16-bit instruction word, and 8-bit data path make it easier to learn than 32-bit Cortex-M parts while still offering on-chip peripherals for real-time control.
Key features include a 10-bit ADC with up to 10 channels, a configurable Enhanced Capture/Compare/PWM (ECCP) module, two analog comparators, a hardware USART with LIN support, an SPI/I2C MSSP module, and nanoWatt Technology for power-managed sleep modes. The 28-VQFN (6x6 mm) package with exposed pad provides a low thermal resistance footprint suited to compact PCB designs.
The PIC18F2321 uses a 16-bit-wide Flash program memory interface with a modified Harvard architecture, an 8-level hardware stack, and a self-programmable Flash region for in-field firmware updates. Its instruction decoder supports byte and bit-level operations, table reads/writes, and a hardware multiply (8x8 in one cycle), enabling efficient C and assembly code generation.
Typical applications include consumer appliances, industrial control loops, sensor conditioning, low-end motor control, USB-to-serial bridges (paired with external transceivers), and automotive body modules. The 40 MHz speed, dual timers, and ECCP PWM make the part especially well suited to closed-loop PID tasks where deterministic interrupt latency is required.
When designing with this device, ensure VDD decoupling is placed within 5 mm of the supply pins and that the exposed thermal pad is soldered to a continuous copper pour for proper thermal and electrical grounding. Note the -I/ML suffix indicates the -40C to +85C industrial temperature range and the QFN packaging.
This page synthesizes current distributor stock and pricing, drop-in package-compatible alternatives from the PIC18 family, and practical design notes not covered in the brief manufacturer datasheet summary.
Drop-in alternatives for PIC18F2321-I/ML — 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 PIC18F2321-I/ML (same form factor and footprint) — differing in Package, ADC, Operating Temperature, Maximum CPU Speed, Program Memory (Flash).
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Request AlternativesPIC18F2321-I/ML Maximum Ratings & Electrical Characteristics
| Product Family | PIC18F |
| Core | PIC 8-bit RISC |
| Program Memory Size | 8 KB (4K x 16) Flash |
| RAM | 512 bytes |
| EEPROM | 256 bytes |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Instruction Set Size | 77 single-word instructions |
| ADC | 10-bit, up to 10 channels |
| Capture/Compare/PWM | 1x ECCP module |
| Comparators | 2 analog comparators |
| Communication | EUSART (LIN), MSSP (SPI/I2C) |
| Timers | Multiple 8/16-bit timers |
| Package | 28-VQFN (6x6 mm) with exposed pad |
| Operating Temperature | -40C to +85C (industrial, -I) |
| Mounting Type | Surface Mount |
| RoHS | Compliant |
| Lead-Free | Yes |
PIC18F2321-I/ML Pin Configuration
| Pin 1 | RA2/AN2 — Port A bit 2 / Analog input 2 (also C2OUT reference) |
| Pin 2 | RA3/AN3/VREF+ — Port A bit 3 / Analog input 3 / ADC positive reference |
| Pin 3 | RA4/AN4/T0CKI — Port A bit 4 / Analog input 4 / Timer0 clock input |
| Pin 4 | RA5/AN5/SS — Port A bit 5 / Analog input 5 / SPI slave select |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RA7/OSC1 — Port A bit 7 / Crystal oscillator input |
| Pin 7 | RA6/OSC2 — Port A bit 6 / Crystal oscillator output |
| Pin 8 | RC0/T1CKI — Port C bit 0 / Timer1 clock input |
| Pin 9 | RC1/CCP2 — Port C bit 1 / CCP2 PWM output |
| Pin 10 | RC2/CCP1 — Port C bit 2 / ECCP PWM output |
| Pin 11 | RC3/SCK/SCL — Port C bit 3 / SPI clock / I2C clock |
| Pin 12 | RC4/SDI/SDA — Port C bit 4 / SPI data in / I2C data |
| Pin 13 | RC5/SDO — Port C bit 5 / SPI data out |
| Pin 14 | RC6/TX/CK — Port C bit 6 / EUSART TX / clock |
| Pin 15 | RC7/RX/DT — Port C bit 7 / EUSART RX / data |
| Pin 16 | VSS — Ground reference |
| Pin 17 | VDD — Positive supply |
| Pin 18 | RB0/INT0/AN12 — Port B bit 0 / External interrupt 0 / Analog input 12 |
| Pin 19 | RB1/INT1/AN10 — Port B bit 1 / External interrupt 1 / Analog input 10 |
| Pin 20 | RB2/INT2/AN8 — Port B bit 2 / External interrupt 2 / Analog input 8 |
| Pin 21 | RB3/AN9 — Port B bit 3 / Analog input 9 |
| Pin 22 | RB4/AN11 — Port B bit 4 / Analog input 11 |
| Pin 23 | RB5/CCP3/AN13 — Port B bit 5 / CCP3 / Analog input 13 |
| Pin 24 | RB6/PGC — Port B bit 6 / ICD clock (programming/debug) |
| Pin 25 | RB7/PGD — Port B bit 7 / ICD data (programming/debug) |
| Pin 26 | MCLR/VPP/RE3 — Master clear / programming voltage / Port E bit 3 |
| Pin 27 | RA0/AN0 — Port A bit 0 / Analog input 0 |
| Pin 28 | RA1/AN1 — Port A bit 1 / Analog input 1 |
Typical Applications
PIC18F2321-I/ML is suitable for 6 applications: Industrial Sensor Conditioning and Control, Low-End BLDC and Stepper Motor Drive, Consumer Appliance HMI Boards, Automotive Body and Lighting Modules, Medical Monitoring Subsystems, USB-to-Serial Bridge and Smart Dongles.
Industrial Sensor Conditioning and Control
The PIC18F2321-I/ML fits industrial sensor applications because it provides 10-bit ADC resolution with up to 10 input channels, 512 B RAM, and 40 MHz (10 MIPS) throughput to filter and linearize analog signals. Its nanoWatt sleep modes drop quiescent current for battery-backed sensor nodes. The 28-VQFN's exposed thermal pad supports continuous operation at ambient up to 85C. Typical front-end: signal amplifier -> ADC -> on-chip ECAN-free comms via EUSART -> host PLC. Power dissipation remains under 0.25 W at 40 MHz, fitting tightly spaced sensor modules without forced cooling.
Recommended
Low-End BLDC and Stepper Motor Drive
The PIC18F2321-I/ML's ECCP (Enhanced Capture/Compare/PWM) module and 8/16-bit timers provide independent PWM channels with programmable dead-band, suiting BLDC and stepper commutation loops. At 40 MHz, the control loop updates in under 200 us with deterministic jitter under 1 us. Pairing with gate drivers like MCP15xx (external) yields a compact 4-layer drive stage. The 8 KB Flash accommodates state-machine commutation tables plus sensor-fusion routines. Designers should configure the PWM fault pin to the ECCP shutdown input for hardware-level overcurrent protection.
Recommended
Consumer Appliance HMI Boards
Consumer HMI boards benefit from the PIC18F2321-I/ML's 28-VQFN (6x6 mm) footprint, which keeps PCB real-estate minimal while delivering 77-instruction simplicity for compact display, keypad, and LED-driver firmware. Its 10-bit ADC reads potentiometers and thermistors at sufficient resolution for HVAC and appliance duty cycles. UART MSSP simplifies connection to Wi-Fi/BLE modules for IoT-ready SKUs. Software stacks fit in 8 KB Flash, leaving calibration tables in EEPROM for user preferences that survive power loss.
Recommended
Automotive Body and Lighting Modules
In automotive body controllers (door modules, lighting drivers, mirror controllers), the PIC18F2321 operates reliably across -40C to +85C and supports LIN bus via the on-chip EUSART, allowing peer-to-peer communication with the vehicle BCM at 19.2 kbps. The 28-VQFN package withstands automotive vibration profiles when the exposed pad is properly soldered. ECCP PWM dims LED strings with 10-bit resolution. For higher-reliability automotive (AEC-Q100) requirements, prefer PIC18F-K42 family parts, but PIC18F2321 is widely used in non-safety body domains and aftermarket modules.
Recommended
Medical Monitoring Subsystems
Low-tier medical monitoring subsystems (blood-pressure cuffs, glucose meters, portable spirometers) leverage the PIC18F2321-I/ML's 10-bit ADC, low-power nanoWatt sleep modes (< 1 uA typical), and small 28-QFN footprint. With a single Li-primary cell, sleep-mode current of < 1 uA extends multi-year battery life; active measurement acquires 10-bit samples at hundreds of Hz. PIC18 instruction set fits control code within 8 KB Flash, leaving room for calibration and lookup tables. Note: FDA medical device validation still requires ISO 13485 design controls at the system level, independent of MCU choice.
Recommended
USB-to-Serial Bridge and Smart Dongles
The PIC18F2321-I/ML forms the MCU core of USB-to-serial bridges when paired with an external USB transceiver (MCP2200 or FTDI equivalent); the on-chip EUSART streams data up to 115.2 kbps in standard baud modes. Smart dongles for diagnostics, asset tracking, and wireless provisioning benefit from the 28-QFN's 6x6 mm footprint allowing 'USB-stick' form factors. The 8 KB Flash supports command parsers, vendor request handlers, and field-upgrade bootloaders, while EEPROM stores configuration parameters (serial number, baud default) that survive reflash.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F2321-I/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18LF2321-I/ML | PIC18F2321-E/ML | PIC18F2221-I/ML | PIC18F2321T-I/ML | PIC18F1320-I/ML |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-VQFN (ML, 6x6 mm) | 28-VQFN (ML, 6x6 mm) - same | 28-VQFN (ML, 6x6 mm) - same | 28-VQFN (ML, 6x6 mm) - same | 28-VQFN (ML, 6x6 mm) - same | 28-VQFN (ML, 6x6 mm) - same |
| Flash | 8 KB | 8 KB | 8 KB | 4 KB | 8 KB | 8 KB |
| RAM | 512 B | 512 B | 512 B | 256 B | 512 B | 256 B |
| Max CPU Speed | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 20 MHz |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +125C | -40C to +85C | -40C to +85C | -40C to +85C |
| Operating Voltage | 4.2V to 5.5V | 2.0V to 5.5V | 4.2V to 5.5V | 4.2V to 5.5V | 4.2V to 5.5V | 2.0V to 5.5V |
| ADC | 10-bit | 10-bit | 10-bit | 10-bit | 10-bit | 10-bit |
Key Differentiators
- Standard 4.2-5.5V operation with clear migration path to LF variant (vs PIC18LF2321-I/ML)
- Doubled Flash and RAM density over PIC18F2221 (vs PIC18F2221-I/ML)
- 2x maximum CPU speed over PIC18F1320 (vs PIC18F1320-I/ML)
Design Notes
A common pitfall when designing with the PIC18F2321-I/ML is missing the obligatory 100 nF ceramic decoupling capacitor within 5 mm of each VDD/VSS pair. The exposed thermal pad MUST be soldered to a contiguous ground plane for both thermal relief and electrical reference, otherwise erratic reset behavior may occur under sustained load. Configuration bits (CONFIG1H through CONFIG3H) must be explicitly set in the source code; leaving them at default may enable the internal RC oscillator when an external crystal is fitted, causing timing errors.
At maximum 40 MHz CPU clock and all peripherals active, the PIC18F2321-I/ML dissipates approximately 250 mW; the 28-VQFN thermal pad junction-to-ambient is approximately 30 C/W with a 1 oz copper 4-layer board. Estimated: at 25C ambient, junction rise is ~7.5C. The package is rated for 85C industrial operation; a small copper pour tied to ground extending from the exposed pad helps keep junction temperature within safe limits during transient peaks.
Place the ICSP (In-Circuit Serial Programming) header footprint at the board edge to allow easy debugger (PICkit 3/4 or MPLAB ICD 4) access without removing the chip. Route RB6/PGC and RB7/PGD to the header with series 100 ohm resistors near the MCU for debug isolation. Keep analog traces (RAx/ANx) short and away from PWM/digital switching lines to minimize ADC coupling. The 6x6 mm QFN land pattern requires 0.4 mm pitch QFN routing; use via-in-pad with filled and plated-over pads for solid thermal ground.
Compliance Information
RoHS compliant per Microchip product page. Not AEC-Q100 qualified; for AEC-Q100 automotive MCU applications, choose PIC18F-K42 family or PIC18F-Q43 family parts.
