PIC18LF2321T-I/SS - 8KB Flash 8-bit MCU 40MHz 28-SSOP | Microchip
MPN: PIC18LF2321T-I/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.18 | $3.18 |
| 10 | $2.86 | $28.60 |
| 100 | $2.55 | $255.00 |
| 500 | $2.3 | $1,150.00 |
| 1,000 | $2.05 | $2,050.00 |
PIC18LF2321T-I/SS Overview
The PIC18LF family belongs to the broader category of 8-bit RISC microcontrollers, which are used as the primary control element in countless embedded products. The LF prefix designates the low-Vdd variant, supporting operation from 2.0 V to 5.5 V, versus the standard PIC18F family which operates from 4.2 V to 5.5 V. The 28-SSOP footprint is one of the most widely used SMD MCU packages, enabling compact board designs and a wide migration path to other PIC18F/LF devices in the same family.
Key features include 25 digital I/O pins with interrupt-on-change support, an internal oscillator block (31 kHz to 8 MHz selectable, with PLL up to 40 MHz), 10-bit ADC with up to 9 channels, two 8-bit timers plus three 16-bit timers, two PWM modules, an enhanced USART, and nanoWatt technology for sub-microamp sleep currents. The integrated ICSP (In-Circuit Serial Programming) and ICD (In-Circuit Debug) interfaces enable easy in-field programming and debug without removing the device from the board.
Architecturally, the device uses Microchip's enhanced PIC18 Harvard RISC core with a 16-bit instruction word and an 8-bit data path. The Flash program memory is self-programmable under software control, supporting bootloader designs and field firmware upgrades without external programmers. The wide operating voltage range combined with nanoWatt power management makes the part suitable for both battery-powered and line-powered applications.
Typical applications include industrial sensor interface boards, low-voltage LCD/keypad user interfaces, small appliance controllers, USB-to-UART bridges (when paired with a USB transceiver), home automation nodes, and battery-powered data loggers. The combination of Flash, EEPROM, and nanoWatt sleep modes makes this part especially attractive for designs that require field-upgradeable firmware and very low standby power.
When designing with this device, ensure the supply decoupling network follows Microchip's recommended 100 nF ceramic in parallel with a bulk capacitor near VDD/VSS, and respect the 2.0 V minimum VDD for LF-variant operation. For automotive or extended-temperature environments, use the PIC18F2321 (F variant) instead.
This page synthesizes distributor pricing, drop-in alternatives within the same 28-SSOP footprint, and practical design notes not aggregated in the manufacturer datasheet.
Drop-in alternatives for PIC18LF2321T-I/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 PIC18LF2321T-I/SS (same form factor and footprint) — differing in Package, Timers, ADC, Program Memory (Flash), Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18LF2321-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F2321T-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF2221T-I/ML
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.84 / Unit
View Datasheet →PIC18LF2320T-I/SO
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$3.75 / Unit
View Datasheet →PIC18F2321T-I/ML
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.96 / Unit
View Datasheet →PIC18LF13K50T-I/SS
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18LF14K22T-I/SS
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.67 / Unit
View Datasheet →PIC18LF2321T-I/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18 (8-bit RISC, Harvard) |
| Program Memory (Flash) | 8 KB (4K x 16 words) |
| RAM | 512 bytes |
| EEPROM | 256 bytes |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Operating Voltage (LF) | 2.0 V to 5.5 V |
| Digital I/O Pins | 25 |
| ADC | 10-bit, up to 9 channels |
| Timers | 2 x 8-bit + 3 x 16-bit |
| PWM Modules | 2 (10-bit) |
| Communication | 1 x EUSART, 1 x MSSP (SPI / I2C) |
| Package | 28-SSOP (209 mil) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial, I grade) |
| Instruction Set | 77 single-word instructions |
| ICSP / ICD | Yes (In-Circuit Serial Programming / Debug) |
| Power-Saving Modes | nanoWatt (multiple idle/sleep modes) |
| RoHS Status | Compliant |
PIC18LF2321T-I/SS Pin Configuration
| Pin 1 | MCLR/VPP/RE3 — Master Clear (reset) input / programming voltage / digital input |
| 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/TOCKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / analog input 4 / SPI slave select |
| Pin 8 | VSS — Ground |
| Pin 9 | OSC1/RA7 — Crystal oscillator input / PORTA bit 7 |
| Pin 10 | OSC2/RA6 — Crystal oscillator output / PORTA bit 6 |
| Pin 11 | RC0/T1OSO/T13CKI — PORTC bit 0 / Timer1 oscillator output / Timer1/Timer3 clock input |
| Pin 12 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 PWM output |
| Pin 13 | RC2/CCP1 — PORTC bit 2 / CCP1 PWM output |
| 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 / EUSART TX / clock |
| Pin 18 | RC7/RX/DT — PORTC bit 7 / EUSART RX / data |
| Pin 19 | VSS — Ground |
| Pin 20 | VDD — Positive supply voltage |
| Pin 21 | RB0/INT0/AN12 — PORTB bit 0 / external interrupt 0 / analog input 12 |
| Pin 22 | RB1/INT1/AN10 — PORTB bit 1 / external interrupt 1 / analog input 10 |
| Pin 23 | RB2/INT2/AN8 — PORTB bit 2 / external interrupt 2 / analog input 8 |
| Pin 24 | RB3/AN9/CCP2 — PORTB bit 3 / analog input 9 / CCP2 alt |
| Pin 25 | RB4/KBI0/AN11 — PORTB bit 4 / interrupt-on-change bit 0 / analog input 11 |
| Pin 26 | RB5/KBI1/PGM — PORTB bit 5 / interrupt-on-change bit 1 / LVP programming |
| Pin 27 | RB6/KBI2/PGC — PORTB bit 6 / interrupt-on-change bit 2 / ICSP clock |
| Pin 28 | RB7/KBI3/PGD — PORTB bit 7 / interrupt-on-change bit 3 / ICSP data |
Typical Applications
PIC18LF2321T-I/SS is suitable for 6 applications: Industrial Sensor Interface Board, Battery-Powered Data Logger, Home Automation Control Node, Small Appliance Controller (Coffee Machine, Mixer), LCD/Keypad User Interface Module, RS-232 / RS-485 Field Sensor Bridge.
Industrial Sensor Interface Board
The PIC18LF2321T-I/SS is well suited for industrial 4 mA to 20 mA sensor transmitters and PLC analog input modules thanks to its 10-bit ADC with up to 9 channels and 2.0 V to 5.5 V wide supply tolerance. Placed as the main controller, the device samples analog inputs, performs linearization in firmware, and drives an isolated UART back to the PLC. The 40 MHz core provides 10 MIPS, easily handling multi-channel acquisition plus MODBUS ASCII/RTU framing at 115200 baud. Compared with discrete op-amp + ADC solutions, the integrated MCU shrinks BOM by 60 percent while the 28-SSOP footprint eases conformal-coating layout.
Recommended
Battery-Powered Data Logger
For remote battery-powered sensor data loggers, the PIC18LF2321T-I/SS delivers sub-1 uA sleep current via nanoWatt technology, allowing multi-year operation on a single 3 V CR2032 coin cell. The internal 256-byte EEPROM provides non-volatile storage for configuration and calibration constants, while the 8 KB Flash hosts the application and a small bootloader. The 10-bit ADC reads temperature, humidity, or load-cell sensors at user-defined intervals; between samples, the device sleeps. Compared with discrete RTC + microcontroller designs, integrating RTC-like timing into nanoWatt sleep modes eliminates the external RTC and reduces BOM cost and standby current.
Recommended
Home Automation Control Node
In Zigbee/Matter/LoRa home automation gateway nodes, the PIC18LF2321T-I/SS serves as a low-cost secondary controller for sensor aggregation and relay control. With 25 GPIO pins, the device can directly drive multi-channel SSR outputs, scan keypad inputs, and talk to a host SoC via EUSART. The wide 2.0 V to 5.5 V supply tolerance allows direct battery or USB bus operation. The ICSP interface enables field firmware upgrades without removing the module. Compared with bigger ARM Cortex-M0 solutions, the PIC18's smaller code footprint and simpler toolchain speed up development for cost-sensitive consumer devices.
Recommended
Small Appliance Controller (Coffee Machine, Mixer)
The PIC18LF2321T-I/SS is a workhorse controller in small kitchen appliances such as coffee machines, stand mixers, and induction cooktops. Its 2 PWM channels directly drive TRIAC-based heater control, while the ADC reads NTC thermistors for closed-loop temperature regulation. The 256-byte EEPROM stores user presets (cup size, brew strength) across power cycles. Industrial-grade -40 C to +85 C operation tolerates the harsh thermal environment inside an appliance chassis. Compared with mechanical timers and discrete analog controllers, the integrated MCU adds programmable profiles and self-diagnostics without raising unit cost.
Recommended
LCD/Keypad User Interface Module
For HMI panels using character LCDs and matrix keypads, the PIC18LF2321T-I/SS provides ample GPIO for an 8-bit data bus plus 4-bit keypad scan with interrupt-on-change wakeup. The MSSP peripheral drives the LCD in 4-bit SPI mode with zero CPU overhead using DMA-style buffering. The 40 MHz clock generates smooth menus and responsive key feedback without flicker. The 8 KB Flash accommodates multi-language UI strings, while the EEPROM saves user settings. Compared with dedicated LCD controller chips, integrating the UI controller into the main MCU reduces board area and total cost.
Recommended
RS-232 / RS-485 Field Sensor Bridge
As a low-cost bridge between legacy RS-232 sensors and modern RS-485 networks, the PIC18LF2321T-I/SS implements both protocols simultaneously via the EUSART and a software bit-banged UART. The wide 2.0 V to 5.5 V supply supports direct interface to both 3.3 V and 5 V transceivers. The 10 MIPS CPU handles protocol conversion at 115200 baud without buffer overruns. Industrial temperature rating allows deployment in factory cabinets. Compared with dedicated protocol-converter ASICs, the PIC18 LF implementation is firmware-upgradeable for new protocol variants.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF2321T-I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18LF2321-I/SS | PIC18F2321T-I/SS | PIC18LF2221T-I/ML | PIC18LF2320T-I/SO |
|---|---|---|---|---|---|
| Package | 28-SSOP (209 mil) | 28-SSOP (209 mil) - same | 28-SSOP (209 mil) - same | 28-QFN (6x6) | 28-SOIC (300 mil) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Operating Voltage | 2.0 V to 5.5 V (LF) | 2.0 V to 5.5 V (LF) | 4.2 V to 5.5 V (F) | 2.0 V to 5.5 V (LF) | 2.0 V to 5.5 V (LF) |
| Flash Memory | 8 KB | 8 KB | 8 KB | 4 KB | 8 KB |
| RAM | 512 B | 512 B | 512 B | 512 B | 512 B |
| EEPROM | 256 B | 256 B | 256 B | 256 B | 256 B |
| CPU Speed | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS | 40 MHz / 10 MIPS |
| I/O Pins | 25 | 25 | 25 | 25 | 25 |
| Variant Suffix | LF (low Vdd), T (T&R) | LF, no T (Tube) | F, T&R | LF, /ML package | LF, /SO package |
| Approx. Unit Price (qty 1) | $3.18 | ~$3.18 | ~$3.45 | ~$3.10 | ~$3.20 |
Key Differentiators
- Lowest operating voltage (2.0 V) in PIC18 family for battery designs (vs PIC18F2321T-I/SS)
- True drop-in same-package replacement with identical silicon (vs PIC18LF2321-I/SS)
- Full nanoWatt power management for sub-uA sleep (vs PIC18LF2221T-I/ML)
- Industrial temperature grade (-40 to +85 C) standard (vs PIC18LC2321T-I/SS (if existed))
Design Notes
Place a 100 nF ceramic decoupling capacitor as close as possible to each VDD/VSS pin pair, with a 10 uF bulk capacitor on the main supply rail. The LF variant operates from 2.0 V to 5.5 V; for designs that may see supply transients above 5.5 V (e.g. 24 V industrial rails), add a TVS diode and LDO upstream. Estimated: at 40 MHz and 5 V supply, active current is approximately 11 mA per the Microchip datasheet typical curve.
The 28-SSOP has 0.65 mm pitch traces - ensure PCB fabrication supports fine-pitch (use 0.2 mm trace/space minimum). Route the ICSP lines (PGC/PGD/MCLR) away from switching power or motor driver traces to avoid programming/debug interference. For high-noise environments, add 4.7 kOhm pull-ups on I2C SDA/SCL and a 100 kOhm pull-down on MCLR to prevent spurious resets.
Do NOT use the LF variant below 2.0 V - the Flash write/erase and ADC accuracy degrade below this threshold. Do NOT drive I/O pins above the absolute maximum of VDD + 0.3 V; even momentary over-voltage can trigger latch-up. Always configure the MCLR pin as a reset input (default) unless using LVP mode, in which case the LVP bit must be cleared before normal operation to prevent accidental entry into programming mode.
At industrial temperature range (-40 C to +85 C), the SSOP package dissipates approximately 250 mW maximum (per JEDEC EIA/JESD51 measurement). In enclosed designs without airflow, derate by 50 percent. For continuous high-current GPIO operation (e.g. 25 mA on multiple pins simultaneously), distribute load across non-adjacent pins to reduce localized die heating.
Compliance Information
RoHS and REACH compliant per Microchip product declarations. Not AEC-Q100 qualified (industrial grade only); for automotive applications use AEC-Q100 qualified PIC18 variants.
