PIC18F2321-E/ML - 8-bit MCU, 8KB Flash, 25MHz | Microchip
MPN: PIC18F2321-E/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.18 | $5.18 |
| 10 | $4.86 | $48.60 |
| 100 | $4.32 | $432.00 |
| 500 | $3.92 | $1,960.00 |
| 1,000 | $3.55 | $3,550.00 |
PIC18F2321-E/ML Overview
A microcontroller (MCU) is a single-chip computer containing a CPU core, program memory, RAM, and integrated peripherals such as ADCs, timers, and communication interfaces. PIC18 microcontrollers sit in the mid-range 8-bit hierarchy (PIC10/12/16/18 family -> 8-bit MCU -> microcontroller -> embedded IC) and use a 16-bit instruction set with an 8-bit data path, balancing code efficiency against simplicity. The PIC18F2321 specifically is part of the PIC18F2x21/4x21/4x31 family that scales from 28 to 44 pins with shared peripherals and pinout-compatible memory maps.
Key features of the PIC18F2321-E/ML include nanoWatt technology with multiple low-power modes (Sleep, Idle, and RTCC alarm wake-up), an internal oscillator block, self-programmability for in-field firmware updates, ICD (In-Circuit Debug) support, and a synchronous serial port configurable as SPI (3-wire) or I2C (2-wire). The 10-bit ADC provides 10 channels of conversion with selectable acquisition time, and two analog comparators with configurable reference allow mixed-signal designs without external components.
Architecturally, the PIC18F2321 uses an enhanced Harvard architecture with separate program and data buses, supporting linear memory addressing up to 2 MB. Its instruction set is C-compiler-friendly, and the device supports 75 instructions plus a hardware multiplier for 8x8 unsigned multiply in one cycle. Wide operating voltage (2.0V to 5.5V typical; the -E suffix denotes the extended -40C to +125C temperature grade) and robust ESD protection suit industrial environments.
Typical applications include industrial control nodes, sensor signal conditioning with on-chip ADC, low-power battery-powered remote sensors, automotive body and HVAC controllers, and consumer appliance control boards. Designers favor this part for its combination of legacy code compatibility, ample analog integration, and broad tool support (MPLAB X, XC8 compiler, PICkit programmers).
When designing with this MCU, ensure decoupling on VDD/AVDD/VSS with 100nF ceramics at each pin pair, plus a 10uF bulk capacitor on the main supply rail. Configure unused I/O as outputs low and disable unused peripherals via firmware to minimize current draw in Sleep mode.
This page synthesizes distributor pricing, parametric comparison with drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone - including nanoWatt mode trade-offs and pin-compatible migration paths within the PIC18F2xxx family.
Drop-in alternatives for PIC18F2321-E/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-E/ML (same form factor and footprint) — differing in Package, Operating Temperature, ADC, Maximum CPU Speed, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F2321-I/ML
✅ Drop-In✓ In Stock
$3.17 / Unit
View Datasheet →PIC18F2421-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2221-E/ML
✅ Drop-In✓ In Stock
$2.98 / Unit
View Datasheet →PIC18F2221T-I/ML
✅ Drop-In✓ In Stock
$2.62 / Unit
View Datasheet →PIC18F2320T-I/SO
✅ Drop-In✓ In Stock
$4.1 / Unit
View Datasheet →PIC18F1320-E/ML
✅ Drop-In✓ In Stock
$1.45 / Unit
View Datasheet →PIC18F2321-E/ML Maximum Ratings & Electrical Characteristics
| Core | PIC18 (8-bit RISC) |
| Program Memory (Flash) | 8 KB (4K x 16) |
| RAM | 512 bytes |
| EEPROM | 256 bytes |
| Maximum CPU Speed | 25 MHz (40 MIPS at 10 MHz, 4-clock) |
| Operating Voltage (VDD) | 2.0 V to 5.5 V |
| I/O Pins | 25 |
| ADC | 10-bit, 10 channels |
| Analog Comparators | 2 |
| CCP / ECCP Modules | 2 CCP |
| Package | 28-pin QFN-EP (6x6 mm), ML suffix |
| Operating Temperature | -40C to +125C (-E extended grade) |
| Internal Oscillator | Yes (8 MHz, software-selectable) |
| Self-Programming | Yes (Flash ICSP) |
| In-Circuit Debug | Yes (ICD) |
| Serial Interfaces | 1x MSSP (SPI/I2C), 1x EUSART |
| Low-Power Modes | nanoWatt (Run, Idle, Sleep, RTCC wake) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
PIC18F2321-E/ML Pin Configuration
| Pin 1 | RA0/AN0 — Digital I/O / Analog input channel 0 |
| Pin 2 | RA1/AN1 — Digital I/O / Analog input channel 1 |
| Pin 3 | RA2/AN2/VREF- — Digital I/O / Analog input channel 2 / ADC negative reference |
| Pin 4 | RA3/AN3/VREF+ — Digital I/O / Analog input channel 3 / ADC positive reference |
| Pin 5 | RA4/T0CKI/C1OUT — Digital I/O / Timer0 clock input / Comparator 1 output |
| Pin 6 | RA5/AN4/SS/C2OUT — Digital I/O / Analog input channel 4 / SPI slave select / Comparator 2 output |
| Pin 7 | RA6/OSC2/CLKO — Digital I/O / Oscillator output / Clock output |
| Pin 8 | RA7/OSC1/CLKI — Digital I/O / Oscillator input / Clock input |
| Pin 9 | VSS — Ground reference |
| Pin 10 | VDD — Positive supply voltage |
| Pin 11 | RC0/T1OSO/T1CKI — Digital I/O / Timer1 oscillator output / Timer1 clock input |
| Pin 12 | RC1/T1OSI/CCP2 — Digital I/O / Timer1 oscillator input / CCP2 module |
| Pin 13 | RC2/CCP1 — Digital I/O / CCP1 module (PWM/capture/compare) |
| Pin 14 | RC3/SCK/SCL — Digital I/O / SPI clock / I2C clock |
| Pin 15 | RC4/SDI/SDA — Digital I/O / SPI data in / I2C data |
| Pin 16 | RC5/SDO — Digital I/O / SPI data out |
| Pin 17 | RC6/TX/CK — Digital I/O / EUSART TX / EUSART clock |
| Pin 18 | RC7/RX/DT — Digital I/O / EUSART RX / EUSART data |
| Pin 19 | RD0 — Digital I/O port D |
| Pin 20 | RD1 — Digital I/O port D |
| Pin 21 | RD2 — Digital I/O port D |
| Pin 22 | RD3 — Digital I/O port D |
| Pin 23 | RD4 — Digital I/O port D |
| Pin 24 | RD5 — Digital I/O port D |
| Pin 25 | RD6 — Digital I/O port D |
| Pin 26 | RD7 — Digital I/O port D |
| Pin 27 | VSS — Ground reference |
| Pin 28 | VDD — Positive supply voltage |
| Pin EP | EP — Exposed thermal pad - must be soldered to ground pour for thermal dissipation |
Typical Applications
PIC18F2321-E/ML is suitable for 6 applications: Industrial Sensor Node with ADC, Low-Power Battery Sensor / IoT Edge Node, Automotive Body and HVAC Controller, Consumer Appliance Control Board, Motor Control / PWM Driver Front-End, Handheld Test & Measurement Instrument.
Industrial Sensor Node with ADC
The PIC18F2321-E/ML is well-suited for industrial sensor-conditioning nodes that digitize analog signals on 4-20 mA loops, thermistor bridges, or strain gauges. Its 10-channel 10-bit ADC with 25 I/O pins is sufficient to multiplex multiple sensor inputs while the nanoWatt Sleep mode draws only microamp-level quiescent current between conversions. The wide 2.0-5.5V VDD range accepts 3.3V or 5V rail directly. Placed near sensor connectors with 100nF ceramic decoupling at each VDD/AVDD pin, the MCU reads via ADC and reports through MSSP-based SPI or I2C to a host controller. Unlike a 32-bit ARM Cortex-M0 alternative, the PIC18F2321 keeps BOM cost under $4 in 1k volume, and the -40C to +125C E-grade temperature rating supports outdoor or under-cabinet installations.
Recommended
Low-Power Battery Sensor / IoT Edge Node
The PIC18F2321-E/ML's nanoWatt technology makes it a strong fit for battery-powered edge sensors that sleep most of the time and wake on the RTCC alarm or external interrupt. With Sleep current measured in sub-microamp range, a single CR2032 cell can power a multi-year deployment. The internal 8MHz oscillator eliminates the external crystal and its quiescent draw, while the 10-bit ADC acquires sensor data on demand before the MCU returns to Sleep. EUSART or MSSP-based SPI/I2C connects to a sub-GHz radio module or BLE companion IC. Compared to an ESP32-class Wi-Fi MCU drawing 80mA active, the PIC18F2321 keeps average system current in the tens of microamps, justifying its $5 unit cost with extended battery life.
Recommended
Automotive Body and HVAC Controller
The PIC18F2321-E/ML's -40C to +125C extended temperature grade and 5V native operation suit automotive body controllers, HVAC actuators, and seat control modules where reliability under hood and cabin thermal stress is required. The two CCP modules generate PWM for DC motor or LED driver stages, while the two analog comparators handle overcurrent detection without an external op-amp. 25 I/O pins accommodate multi-channel switch scanning, LIN slave bus via EUSART, and 10-bit ADC for thermistor temperature feedback. Place the MCU adjacent to the power driver ICs to minimize PWM-induced ground bounce, and tie the QFN exposed pad to a 1 sq inch copper pour for thermal relief. The -E grade directly meets AEC-Q100 environments with proper PCB layout.
Recommended
Consumer Appliance Control Board
The PIC18F2321-E/ML serves cost-sensitive consumer appliances such as washing-machine user-interface boards, microwave keypad controllers, and dishwasher timers where 8KB of Flash is ample for the user-interface state machine. The 25 I/O drive 7-segment LEDs, triac zero-cross drivers, and buzzer outputs, while the 10-bit ADC reads temperature or humidity sensors directly. Self-programmability via Flash ICSP lets manufacturers ship firmware updates without physical replacement. Compared to a CPLD or discrete logic alternative, the PIC18F2321 at $3.55 (qty 1000) replaces 3-5 logic ICs, lowering assembly cost and PCB area. The -E grade handles laundry-room temperature cycles without thermal derating.
Recommended
Motor Control / PWM Driver Front-End
The PIC18F2321-E/ML's two CCP modules generate complementary or independent PWM outputs up to 25MHz timer clock, sufficient for brushed DC motor speed control, fan speed regulation, or LED dimming. The 10-bit ADC samples back-EMF or current-sense shunt resistors in real time, while the analog comparators provide hardware overcurrent protection independent of firmware latency. Up to 25 I/O drive gate-driver enable pins and status LEDs. For cost-sensitive BLDC or stepper control, this MCU replaces a dedicated motor-control IC in low-power applications; designers migrating to higher-power systems can step up to the dsPIC33 family with field-oriented control libraries.
Recommended
Handheld Test & Measurement Instrument
The PIC18F2321-E/ML fits portable DMMs, signal-tracer probes, and bench-top sensor calibrators that need a low-cost MCU with on-chip ADC and self-programmable Flash for field firmware updates. The MSSP provides SPI for an LCD driver IC, while the EUSART drives an isolated USB-to-UART bridge. nanoWatt Sleep modes keep battery drain low during standby; the internal 8MHz oscillator eliminates a crystal that would otherwise consume quiescent current. Compare to an STM32G0 alternative costing 2-3x more - the PIC18F2321-E/ML at $5 unit price is a deliberate cost-down choice for high-volume handheld instruments where 8KB Flash is sufficient for the measurement firmware.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F2321-E/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F2321-I/ML | PIC18F2421-I/ML | PIC18F2221-E/ML | PIC18F2221T-I/ML | PIC18F1320-E/ML |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-QFN-EP (6x6 mm) | 28-QFN-EP (6x6 mm) - same | 28-QFN-EP (6x6 mm) - same | 28-QFN-EP (6x6 mm) - same | 28-QFN-EP (6x6 mm) - same | 28-QFN-EP (6x6 mm) - same |
| Flash Memory | 8 KB | 8 KB | 16 KB | 4 KB | 4 KB | 8 KB |
| RAM | 512 bytes | 512 bytes | 768 bytes | 256 bytes | 256 bytes | 256 bytes |
| EEPROM | 256 bytes | 256 bytes | 256 bytes | 256 bytes | 256 bytes | 256 bytes |
| Operating Temperature | -40C to +125C (E grade) | -40C to +85C (I grade) | -40C to +85C (I grade) | -40C to +125C (E grade) | -40C to +85C (I grade) | -40C to +125C (E grade) |
Key Differentiators
- Extended -40C to +125C temperature grade (vs PIC18F2321-I/ML)
- 8KB Flash / 512B RAM balanced density (vs PIC18F2221-E/ML)
- Compact 28-QFN-EP (6x6 mm) footprint (vs PIC18F4550-I/P)
Design Notes
Place a 100nF ceramic decoupling capacitor as close as physically possible to each VDD/AVDD pin pair, plus a single 10uF bulk tantalum or ceramic capacitor on the main supply rail within 1 inch of the MCU. The PIC18F2321 has separate VDD/VSS pins on opposite sides of the QFN package; route both pairs to the ground/power planes with wide traces. The exposed thermal pad must be soldered to a copper ground pour to provide the chip's main thermal dissipation path.
The QFN-EP package dissipates heat through the exposed pad to the PCB copper pour. For continuous operation near 10 MIPS at 5V with all peripherals active, design for at least 100 sq mm of ground copper connected to the EP. Without proper EP soldering, junction temperature can exceed 125C at high ambient even within rated load. Use a star-ground topology tying the EP pour back to the main ground plane via a single low-inductance via cluster.
Configure all unused I/O pins as outputs driving low, and disable unused peripherals via firmware (PMD registers) to minimize quiescent current drain - a common PIC18 design pitfall is leaving unused pins floating, which can inject noise and draw tens of microamps per pin. When migrating firmware from PIC18F2221 to PIC18F2321, verify the Flash/RAM partition; code compiled for 4KB will link but the larger 8KB image wastes Flash if not intentional.
Keep analog inputs (RA0-RA5) physically separated from switching digital lines and PWM outputs (CCP1, CCP2 on RC2/RC1) on the PCB to reduce ADC crosstalk. Route the analog reference (VREF+/VREF-) pins with short, guarded traces if used; otherwise tie VREF+ to VDD and VREF- to VSS. Place the analog ground (AGND) tie point directly under the MCU EP rather than routing it as a separate trace.
Compliance Information
RoHS and lead-free compliance per Microchip product page. AEC-Q100 qualification is not separately listed for PIC18F2321-E/ML standard part; the -E temperature grade supports automotive environments but does not by itself confer AEC-Q100 status. Confirm AEC-Q100 status with Microchip documentation for automotive PPAP submissions.
