PIC18F2321-E/SS - 8-bit 25MHz MCU, 8KB Flash, 28-SSOP | Microchip
MPN: PIC18F2321-E/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.38 | $5.38 |
| 10 | $4.92 | $49.20 |
| 100 | $4.31 | $431.00 |
| 500 | $3.78 | $1,890.00 |
| 1,000 | $3.3 | $3,300.00 |
PIC18F2321-E/SS Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, memory, and peripherals on one die. The PIC18 family uses Microchip's enhanced Harvard RISC architecture with 77 single-word instructions, placing these parts in the hierarchy: microcontroller -> embedded MCU -> 8-bit MCU -> PIC18 family -> CMOS Flash MCU. The 'F' suffix indicates Flash program memory (vs. older ROM/EPROM), while the PIC18 line is the entry tier above PIC16, offering linear memory access, prioritized interrupts, and a 16-bit instruction word that improves code density.
Key features of the PIC18F2321-E/SS include a 10-bit Analog-to-Digital Converter (ADC) with up to 10 input channels, two analog comparators, two Capture/Compare/PWM (CCP) modules, a master Synchronous Serial Port (SSP) configurable as SPI or I2C, and nanoWatt power management for low-power operation. The 'E' suffix indicates the Extended temperature grade of -40C to +125C, while the '/SS' suffix denotes the 28-pin Shrink Small Outline Package (SSOP) suited for compact designs.
The architecture uses an 8-bit data path with a 16-bit instruction word, separate program and data buses (Harvard), a hardware multiplier (8x8 single-cycle), and a 32-level hardware stack. nanoWatt Technology provides multiple idle/sleep modes with on-the-fly oscillator switching to balance compute throughput against quiescent draw. The 10-bit ADC with successive approximation delivers conversion in ~16 instruction cycles and can be used for sensor monitoring in industrial control loops.
Typical applications include industrial sensor signal conditioning, motor control peripherals, HVAC actuator interfaces, automotive body electronics (extended temperature grade), low-cost consumer devices, and battery-powered sensor nodes. The combination of CCP, ADC, comparators, and SSP makes the PIC18F2321 a versatile general-purpose controller for embedded designs where deterministic response and small footprint are priorities.
When designing with this part, ensure decoupling capacitors (0.1 uF ceramic plus bulk) are placed close to VDD/VSS pairs, configure the configuration bits correctly for the chosen oscillator mode, and use the In-Circuit Serial Programming (ICSP) interface for firmware development. The MCLR pin reset behavior and brown-out reset thresholds must be set in configuration words to match the system's noise environment.
This page synthesizes distributor pricing, drop-in same-package alternatives, application guidance, and design notes that go beyond what is in the Microchip datasheet alone. Last verified against distributor and manufacturer data on 2026-09-26.
Drop-in alternatives for PIC18F2321-E/SS — 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/SS (same form factor and footprint) — differing in Operating Temperature, Package, Program Memory (Flash), Timers.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F2321-I/SS
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC18F2420-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2320-I/SS
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18F2321T-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2221-I/SS
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18F2420-E/SS
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18F2321-E/SS Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit Microcontroller (MCU) |
| Family | PIC18F |
| Architecture | Enhanced Harvard RISC, 16-bit instruction word |
| Instruction Set Size | 77 instructions (single-word) |
| Program Memory (Flash) | 8 KB (4K x 16) |
| Data RAM | 512 bytes |
| Data EEPROM | 256 bytes |
| Maximum Clock Frequency | 40 MHz |
| Instruction Execution Speed | 10 MIPS (100 ns per instruction) |
| Supply Voltage (VDD) | 4.2 V to 5.5 V |
| Operating Temperature | -40 C to +125 C (Extended grade) |
| Digital I/O Pins | 25 |
| ADC | 10-bit, up to 10 input channels |
| Comparators | 2 analog comparators |
| CCP Modules | 2 (Capture/Compare/PWM) |
| Serial Interfaces | 1x SSP (SPI or I2C), USART |
| Timers | 4 (TMR0-TMR3) |
| Package | 28-pin SSOP |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
PIC18F2321-E/SS Pin Configuration
| Pin 1 | MCLR/VPP/RE3 — Master Clear reset (active low) / programming voltage / digital input RE3 |
| Pin 2 | RA0/AN0 — PORTA bit 0 / analog input AN0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / analog input AN1 |
| Pin 4 | RA2/AN2/VREF- — PORTA bit 2 / analog input AN2 / ADC negative reference |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / analog input AN3 / ADC positive reference |
| Pin 6 | RA4/T0CKI/C1OUT — PORTA bit 4 / Timer0 clock input / comparator 1 output |
| Pin 7 | RA5/AN4/SS/C2OUT — PORTA bit 5 / analog input AN4 / SSP slave select / comparator 2 output |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKI/RA7 — Oscillator crystal input / external clock input / PORTA bit 7 |
| Pin 10 | OSC2/CLKO/RA6 — Oscillator crystal output / clock output / PORTA bit 6 |
| Pin 11 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 12 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 output |
| Pin 13 | RC2/CCP1 — PORTC bit 2 / CCP1 PWM/capture/compare |
| Pin 14 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 15 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 16 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 17 | RC6/TX/CK — PORTC bit 6 / USART transmit / USART clock |
| Pin 18 | RC7/RX/DT — PORTC bit 7 / USART receive / USART data |
| Pin 19 | VSS — Ground reference (second pair) |
| Pin 20 | VDD — Positive supply (4.2V to 5.5V) |
| Pin 21 | RB0/INT0/FLT0/AN12 — PORTB bit 0 / external interrupt 0 / PWM fault input / analog input AN12 |
| Pin 22 | RB1/INT1/AN10 — PORTB bit 1 / external interrupt 1 / analog input AN10 |
| Pin 23 | RB2/INT2/AN8 — PORTB bit 2 / external interrupt 2 / analog input AN8 |
| Pin 24 | RB3/AN9/CCP2 — PORTB bit 3 / analog input AN9 / CCP2 alt |
| Pin 25 | RB4/KBI0/AN11 — PORTB bit 4 / interrupt-on-change KBI0 / analog input AN11 |
| Pin 26 | RB5/KBI1/AN13 — PORTB bit 5 / interrupt-on-change KBI1 / analog input AN13 |
| Pin 27 | RB6/KBI2/PGC — PORTB bit 6 / interrupt-on-change KBI2 / ICSP clock |
| Pin 28 | RB7/KBI3/PGD — PORTB bit 7 / interrupt-on-change KBI3 / ICSP data |
Typical Applications
PIC18F2321-E/SS is suitable for 6 applications: Industrial Sensor Signal Conditioning, Motor Control Peripherals, HVAC Actuator Interfaces, Low-Cost Consumer Devices, Battery-Powered Sensor Nodes, Automotive Body Electronics.
Industrial Sensor Signal Conditioning
The PIC18F2321-E/SS is well-suited to industrial sensor front-end conditioning thanks to its 10-bit ADC with up to 10 input channels and 2 analog comparators on the same die. Each ADC conversion completes in approximately 16 instruction cycles, and the 8 KB of Flash comfortably holds calibration tables for thermocouple or RTD linearization routines. The Extended -40C to +125C temperature grade allows deployment near motors or in unconditioned enclosures without derating. The SSP module can be configured as SPI or I2C to read out digital sensor chains alongside the analog inputs. In a typical 4-20 mA loop interface, the MCU reads a shunt voltage via the ADC, applies digital filtering in firmware, and drives an isolated 4-20 mA DAC, all on a single 5V rail with deterministic 100 ns instruction timing. The 25 MIPS throughput is sufficient for FIR filtering of low-frequency sensor noise without DMA, simplifying firmware structure.
Recommended
Motor Control Peripherals
For small brushed DC or unipolar stepper motor peripherals, the PIC18F2321-E/SS provides two CCP modules that generate PWM up to 10-bit resolution at the 10 MIPS instruction rate, sufficient for H-bridge gate drivers and velocity profiling. The Enhanced Harvard architecture with hardware 8x8 multiplier handles PI control loops in firmware at typical motor PWM frequencies of 1-20 kHz. With 512 bytes of RAM, the part can hold a control state machine plus PWM duty tables without paging. Back-EMF feedback can be sampled by the 10-bit ADC and compared against setpoints via the on-chip comparators, freeing the CPU for higher-level task scheduling. The 28-SSOP package is small enough for integration into a motor housing PCB, and the Extended temperature grade supports under-hood or motor-bearing-adjacent environments.
Recommended
HVAC Actuator Interfaces
The PIC18F2321-E/SS is a strong fit for HVAC damper and valve actuators where Extended temperature operation and deterministic response are required. The 25 MIPS performance supports simultaneous handling of multiple PWM channels for damper positioning, plus SPI/I2C communication with a building automation bus. The 256 bytes of EEPROM are useful for retaining calibration values (stroke endpoints, zero offsets) across power cycles without external storage. The 10-bit ADC reads position-feedback potentiometers directly, and the analog comparators implement window-watchdog supervision on the actuator shaft encoder. nanoWatt Technology allows the MCU to enter sleep mode between actuator moves, extending battery life in wireless or retrofit installations. The 28-SSOP footprint is mechanically compatible with surface-mount actuator PCBs used in modern HVAC equipment.
Recommended
Low-Cost Consumer Devices
The PIC18F2321-E/SS fits cost-sensitive consumer products such as coffee makers, rice cookers, small kitchen appliances, or toys that need basic user-interface and control features at a low BOM cost. The 10 MIPS instruction rate supports capacitive-touch button scanning, LED matrix driving via multiplexing, and basic PID temperature control without external peripherals. The integrated 10-bit ADC reads NTC thermistors for over-temperature protection, and the CCP modules generate PWM for heating-element control. With 8 KB of Flash the part can store a multi-language UI menu and a small sound-effect library for user feedback. The 28-SSOP is small enough for crowded appliance control boards, and Microchip's nanoWatt sleep modes cut standby power below typical energy-star thresholds.
Recommended
Battery-Powered Sensor Nodes
The PIC18F2321-E/SS is suitable for wireless sensor nodes and battery-powered telemetry devices due to its nanoWatt Technology and flexible sleep modes. The MCU can wake from sleep on a Timer1 overflow or external interrupt, take an ADC reading, transmit it over the SSP (configured as SPI to a radio module), and return to sleep, achieving average currents in the microamp range. The 25 MIPS instruction rate lets the part handle simple encryption or sensor-fusion math between transmissions, while the 8 KB Flash is enough for application code plus a small bootloader for OTA updates. The Extended temperature grade allows outdoor deployment in weather stations or agricultural sensors. The 28-SSOP package suits compact sensor-module PCBs where every square millimeter counts.
Recommended
Automotive Body Electronics
The PIC18F2321-E/SS Extended temperature grade supports automotive body-electronics applications such as seat-position controllers, mirror adjusters, ambient lighting, and HVAC blend-door actuators. While not AEC-Q100 qualified, the part's -40C to +125C operating range meets the thermal demands of non-safety body modules. The 10-bit ADC reads position-feedback pots, the CCP modules drive small motors via half-bridge drivers, and the SSP/I2C connects to body-control networks. The 256-byte EEPROM retains last-position memory across battery disconnects. The 28-SSOP package is a common automotive surface-mount form factor. For designs that require formal AEC-Q100 qualification, Microchip recommends migrating to PIC18F-K42 or PIC18F-Q41 family parts in equivalent packages.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F2321-E/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F2321-I/SS | PIC18F2420-I/SS | PIC18F2320-I/SS | PIC18F2221-I/SS |
|---|---|---|---|---|---|
| Package | 28-SSOP | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory (Flash) | 8 KB | 8 KB | 16 KB | 8 KB | 4 KB |
| Data RAM | 512 B | 512 B | 768 B | 512 B | 256 B |
| EEPROM | 256 B | 256 B | 256 B | 256 B | 256 B |
| ADC | 10-bit, 10 channels | 10-bit, 10 channels | 10-bit, 10 channels | No ADC | 10-bit, 10 channels |
| Operating Temperature | -40C to +125C (Extended) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) |
| Supply Voltage | 4.2 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 | 4.2 V to 5.5 V |
Key Differentiators
- Extended -40C to +125C temperature grade vs industrial -40C to +85C (vs PIC18F2321-I/SS)
- Migration path to 16 KB Flash in same footprint (vs PIC18F2420-I/SS)
- ADC-equipped 28-pin PIC18 with 8 KB Flash (vs PIC18F2320-I/SS)
Design Notes
Place a 0.1 uF ceramic decoupling capacitor as close as physically possible to each VDD/VSS pin pair (pins 11/12 and 19/20 on 28-SSOP). Add a bulk 10 uF tantalum or aluminum capacitor near the IC. Use a star-ground topology if the design mixes analog and digital grounds, with the AGND tied to DGND only at the MCU. The AVDD pin (if present) should be filtered with a ferrite bead from VDD. The MCU will draw approximately 5-15 mA active at 25 MIPS depending on peripheral use.
Configuration bits (CONFIG1H through CONFIG4H) must be set before code runs; an unconfigured device can fail to oscillate, have wrong watchdog behavior, or disable the MCLR reset. Brown-Out Reset voltage should be set above the minimum VDD (4.2V) to prevent code execution at marginal voltages. The ICSP pins (RB6/PGC, RB7/PGD) must not be loaded with heavy capacitance that prevents in-circuit programming; 50 pF maximum is recommended on these pins.
Estimated: at maximum activity (active 25 MIPS, all peripherals on), the PIC18F2321 in 28-SSOP draws approximately 22 mA from 5V, or 110 mW dissipation. With theta_JA of approximately 90 C/W on a 1 oz copper SSOP land pattern, the junction rise is ~10 C above ambient - well within the 125C limit. At -40C cold-start, oscillator stabilization time must be allowed before code execution; use the OST or configuration-bit FOSC settings to ensure proper start-up.
Keep the oscillator traces (OSC1/OSC2) short and symmetric, and surround them with a ground pour to minimize EMI pickup. If using a high-speed external oscillator (HS mode above 4 MHz), place a series resistor on OSC2 to dampen reflections. Trace the ICSP connector to the edge of the PCB so the debugger can attach without removing the board from its enclosure. The MCLR pin should have a 10 kohm pull-up to VDD and a 100 nF cap to ground for noise immunity, with the cap physically close to the pin.
Compliance Information
RoHS compliant per Microchip product page. The PIC18F2321-E/SS is the Extended temperature grade but is NOT AEC-Q100 qualified; for AEC-Q100 designs, choose PIC18F-K42 or PIC18F-Q41 family parts. Lead-free and Pb-free terminations are standard. Halogen-free status not explicitly stated in distributor data.
