PIC18LF4539T-I/ML - 40MHz 8-Bit MCU, 24KB Flash, 44-QFN | Microchip
MPN: PIC18LF4539T-I/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.93 | $4.93 |
| 10 | $4.55 | $45.50 |
| 100 | $4.05 | $405.00 |
| 500 | $3.62 | $1,810.00 |
| 1,000 | $3.2 | $3,200.00 |
PIC18LF4539T-I/ML Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, non-volatile program memory, working RAM, and a rich set of peripherals (I/O, timers, ADC, communications). Within the broader hierarchy of semiconductor devices, an MCU belongs to the family of microcontrollers, which in turn sits under integrated circuits (ICs) and the wider category of digital logic semiconductors. The PIC18 family is Microchip's mid-range 8-bit architecture offering a balance of code density, deterministic interrupt handling and peripheral integration for embedded-control applications.
Key features of the PIC18LF4539T-I/ML include 32 programmable digital I/O pins, an 8-channel 10-bit Analog-to-Digital Converter (ADC), multiple capture/compare/PWM modules, USART, MSSP (SPI/I2C), and dedicated motor-control peripherals consistent with the '4539 part number family. The integrated motor-control kernel supports single-phase induction motor drive, simplifying variable-speed fan/pump designs. The 44-QFN (8x8) package provides a low-profile, thermally efficient footprint for space-constrained boards, with an exposed thermal pad to dissipate controller dissipation.
Architecturally, the PIC18 core delivers a 16-bit instruction word with an 8-bit data path, 31-level hardware stack, hardware multiplier, and linear program memory addressing up to 2 MB. The 'LF' sub-family denotes a wide-voltage (2.0-5.5V) variant, giving design flexibility for both 3.3V and 5V rails. The device is qualified for industrial temperatures (-40C to +85C per the 'I' suffix).
Typical applications include single-phase induction motor control (fans, pumps, small appliances), industrial instrumentation, white goods and HVAC controls, sensor-signal conditioning, and general-purpose 5V/3.3V embedded systems that benefit from integrated EEPROM storage and PWM channels.
When designing with the PIC18LF4539T-I/ML, observe the 44-QFN PCB land pattern and provide adequate copper thermal relief under the exposed pad; the Flash self-programming model relies on the standard PIC18 ICSP/ICD connection on PGC/PGD for in-circuit debugging.
This page synthesizes real-time distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for PIC18LF4539T-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 PIC18LF4539T-I/ML (same form factor and footprint) — differing in Package, ADC, Operating Temperature, Core Architecture, I/O Pins.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18LF4539-I/ML
✅ Drop-In✓ In Stock
$4.3 / Unit
View Datasheet →PIC18LF4539-I/PT
✅ Drop-In✓ In Stock
$4.1 / Unit
View Datasheet →PIC18F4539-I/ML
✅ Drop-In✓ In Stock
$4.1 / Unit
View Datasheet →PIC18LF4523T-I/ML
✅ Drop-In✓ In Stock
$5.95 / Unit
View Datasheet →PIC18LF4520T-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF4321-I/ML
✅ Drop-In✓ In Stock
$4.43 / Unit
View Datasheet →PIC18LF4539T-I/ML Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit (PIC18) |
| CPU Speed (Max) | 40 MHz |
| Program Memory (Flash) | 24 KB (12K x 16) |
| Data RAM | 1408 bytes |
| EEPROM | 256 bytes |
| Programmable I/O Pins | 32 |
| ADC | 8-channel, 10-bit |
| Supply Voltage | 2.0 V to 5.5 V |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Package | 44-QFN (8x8 mm) with exposed thermal pad |
| Mounting Type | Surface Mount |
| Motor Control Kernel | Single-Phase Induction Motor (per datasheet family) |
| Peripherals | USART, MSSP (SPI/I2C), CCP/PWM, Timers |
| ICSP/ICD Debug | Yes (PGC/PGD) |
| RoHS Status | Compliant |
PIC18LF4539T-I/ML Pin Configuration
| Pin 1 | MCLR — Master Clear (Reset) input, active-low |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input 1 |
| Pin 4 | RA2/AN2 — PORTA bit 2 / Analog input 2 |
| Pin 5 | RA3/AN3 — PORTA bit 3 / Analog input 3 |
| Pin 6 | RA4 — PORTA bit 4 (digital I/O) |
| Pin 7 | RA5/AN4 — PORTA bit 5 / Analog input 4 |
| Pin 8 | RE0/RD — PORTE bit 0 / Parallel port read control |
| Pin 9 | RE1/WR — PORTE bit 1 / Parallel port write control |
| Pin 10 | RE2/CS — PORTE bit 2 / Parallel port chip-select |
| Pin 11 | VDD — Positive supply (2.0-5.5 V) |
| Pin 12 | VSS — Ground reference |
| Pin 13 | OSC1/CLKIN — Crystal oscillator input / external clock |
| Pin 14 | OSC2/CLKOUT — Crystal oscillator output |
| Pin 15 | RC0/T1OSO — PORTC bit 0 / Timer1 oscillator output |
| Pin 16 | RC1/T1OSI — PORTC bit 1 / Timer1 oscillator input |
| Pin 17 | RC2/CCP1 — PORTC bit 2 / CCP1 PWM output |
| Pin 18 | RC3 — PORTC bit 3 (digital I/O) |
| Pin 19 | RD0 — PORTD bit 0 |
| Pin 20 | RD1 — PORTD bit 1 |
| Pin 21 | RD2 — PORTD bit 2 |
| Pin 22 | RD3 — PORTD bit 3 |
| Pin 23 | RC4/SDI — PORTC bit 4 / SPI data in |
| Pin 24 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 25 | RC6/TX — PORTC bit 6 / USART transmit |
| Pin 26 | RC7/RX — PORTC bit 7 / USART receive |
| Pin 27 | RD4 — PORTD bit 4 |
| Pin 28 | RD5 — PORTD bit 5 |
| Pin 29 | RD6 — PORTD bit 6 |
| Pin 30 | RD7 — PORTD bit 7 |
| Pin 31 | VSS — Ground reference |
| Pin 32 | VDD — Positive supply (2.0-5.5 V) |
| Pin 33 | RB0/INT0 — PORTB bit 0 / External interrupt 0 |
| Pin 34 | RB1/INT1 — PORTB bit 1 / External interrupt 1 |
| Pin 35 | RB2 — PORTB bit 2 |
| Pin 36 | RB3 — PORTB bit 3 |
| Pin 37 | RB4 — PORTB bit 4 |
| Pin 38 | RB5 — PORTB bit 5 |
| Pin 39 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 40 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 41 | RA6 — PORTA bit 6 |
| Pin 42 | RA7 — PORTA bit 7 |
| Pin 43 | VSS — Ground reference (analog) |
| Pin 44 | AVDD — Analog positive supply |
| Pin EP | EP — Exposed thermal pad - connect to VSS/ground plane |
Typical Applications
PIC18LF4539T-I/ML is suitable for 6 applications: Single-Phase Induction Motor Control, White Goods and HVAC Control Boards, Industrial Instrumentation and Sensor Hubs, Battery-Operated Portable Devices, LED Lighting and Display Drivers, General-Purpose 5V/3.3V Embedded Control.
Single-Phase Induction Motor Control
The PIC18LF4539T-I/ML is designed into single-phase induction motor drives such as small fans, pumps and appliance blowers. Its 40 MHz PIC18 core delivers 10 MIPS of deterministic throughput to execute vectored commutation and closed-loop speed control within the integrated motor-control kernel, while the 8-channel 10-bit ADC samples back-EMF and current-sense signals. The 2.0-5.5 V wide supply lets the MCU share a 3.3 V or 5 V rail with the gate-driver stage, simplifying the BOM. The 44-QFN (8x8) exposed-pad package keeps the thermal path short, suiting enclosed appliance designs where board area is constrained and PCB copper serves as the heatsink.
Recommended
White Goods and HVAC Control Boards
Washing machines, dishwashers, range hoods and HVAC blowers benefit from the PIC18LF4539T-I/ML's industrial -40C to +85C temperature range and on-chip EEPROM for storing calibration and fault logs. The 32 programmable I/O pins interface directly to user keypads, LED indicators, triac drivers and NTC temperature sensors, while the CCP/PWM modules generate zero-crossing-timed phase-angle control for AC loads. Its 24 KB Flash holds the full control state machine plus a small RTOS or cooperative scheduler. The wide-voltage LF supply tolerates rectified 5 V rails common in appliance SMPS designs.
Recommended
Industrial Instrumentation and Sensor Hubs
The PIC18LF4539T-I/ML serves as a low-cost sensor-conditioning hub in industrial controllers, handling 4-20 mA loops, thermistor bridges and digital sensors via SPI or I2C (MSSP). Its 8-channel 10-bit ADC supports multiple analog inputs simultaneously, while 32 I/O pins drive status LEDs, relay drivers and keypad scanning. The 24 KB Flash accommodates Modbus RTU or proprietary fieldbus stacks. The wide 2.0-5.5 V supply lets the same board run from 24 V industrial rails with a small linear post-regulator. The 44-QFN (8x8) footprint suits DIN-rail mounted backplanes where vertical clearance is limited.
Recommended
Battery-Operated Portable Devices
The PIC18LF4539T-I/ML 'LF' variant's 2.0 V minimum supply enables direct operation from two alkaline cells or a single Li-ion cell across its full discharge curve. Its low-power Sleep mode (typically under 1 uA with peripherals disabled, per PIC18F family datasheets) extends runtime in handheld instruments, portable monitors and remote sensor pods. The 256-byte EEPROM preserves calibration constants across battery swaps. With 24 KB Flash, designers embed small protocol stacks or data-logging firmware without external memory. The 44-QFN (8x8) package keeps the PCB below 25 mm square for compact wearables and handheld enclosures.
Recommended
LED Lighting and Display Drivers
Lighting controllers and signage panels leverage the PIC18LF4539T-I/ML's CCP/PWM channels for multi-channel dimming and color-mixing. At 40 MHz the PIC18 core generates smooth 8-bit or 10-bit PWM at high update rates with minimal CPU overhead, freeing cycles for DMX-512 or DALI protocol parsing. The wide-voltage LF supply (2.0-5.5 V) supports 3.3 V logic-level LED drivers and 5 V analog dimming interfaces. The 24 KB Flash stores lighting presets and chase-pattern macros, while 256-byte EEPROM retains user configuration across power cycles. The 44-QFN footprint fits slim LED bar PCBs.
Recommended
General-Purpose 5V/3.3V Embedded Control
Beyond motor control, the PIC18LF4539T-I/ML is a versatile general-purpose MCU for products that need 32 I/O, 24 KB Flash and an 8-channel ADC. The wide-voltage supply eases migration between 5 V legacy systems and newer 3.3 V designs without changing the firmware, and the integrated EEPROM avoids an external memory chip. The USART and MSSP peripherals support legacy RS-232, SPI peripherals and I2C sensors. The 44-QFN (8x8) industrial-grade package suits products that must survive harsh factory-floor environments with limited board area.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF4539T-I/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18LF4539-I/ML | PIC18LF4539-I/PT | PIC18F4539-I/ML | PIC18LF4523T-I/ML | PIC18LF4520T-I/ML | PIC18LF4321-I/ML |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-QFN (8x8 mm) | 44-QFN (8x8 mm) - same | 44-QFN (8x8 mm) - same | 44-QFN (8x8 mm) - same | 44-QFN (8x8 mm) - same | 44-QFN (8x8 mm) - same | 44-QFN (8x8 mm) - same |
| Core | PIC18 8-bit | PIC18 8-bit | PIC18 8-bit | PIC18 8-bit | PIC18 8-bit | PIC18 8-bit | PIC18 8-bit |
| Max CPU Speed | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz |
| Flash Program Memory | 24 KB | 24 KB | 24 KB | 24 KB | 32 KB | 32 KB | 8 KB |
| RAM | 1408 B | 1408 B | 1408 B | 1408 B | 1536 B | 1536 B | 512 B |
| EEPROM | 256 B | 256 B | 256 B | 256 B | 256 B | 256 B | 256 B |
| Programmable I/O Pins | 32 | 32 | 32 | 32 | 36 | 36 | 34 |
| ADC | 8-ch, 10-bit | 8-ch, 10-bit | 8-ch, 10-bit | 8-ch, 10-bit | 12-ch, 10-bit | 13-ch, 10-bit | 8-ch, 10-bit |
| Supply Voltage | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 4.2 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V |
| Motor Control Kernel | Yes (single-phase induction) | Yes (single-phase induction) | Yes (single-phase induction) | Yes (single-phase induction) | No (general purpose) | No (general purpose) | No (general purpose) |
Key Differentiators
- Integrated single-phase induction motor-control kernel (vs PIC18LF4520T-I/ML)
- Wide-voltage 2.0-5.5 V supply range for battery designs (vs PIC18F4539-I/ML)
- 24 KB Flash matches typical motor-control firmware size without external memory (vs PIC18LF4321-I/ML)
- Industrial -40 C to +85 C temperature range for harsh environments (vs PIC18LF4439T-I/ML (different pin map))
Design Notes
The 44-QFN (8x8) package exposes a center thermal pad that MUST be soldered to a ground-copper pour with multiple thermal vias to keep junction temperature within the -40 C to +85 C industrial range. Estimated: at full 40 MHz CPU activity with all peripherals enabled and VDD=5 V, the PIC18LF4539T-I/ML consumes approximately 25 mA (125 mW). On a 1 sq-in. copper area the device stays well below the 85 C ambient ceiling; without the exposed-pad solder joint the junction can exceed ratings in enclosed appliances. Always stencil the EP with solder paste per JEDEC QFN profile recommendations.
Place a 100 nF decoupling capacitor as close as possible to each VDD/VSS pin pair (the device has three VDD/VSS pairs plus a separate AVDD). Add a bulk 10 uF tantalum or ceramic cap on the main VDD rail. The MCLR pin requires a 10 kohm pull-up to VDD; if ICD is used, route PGC (RB6) and PGD (RB7) with short, parallel traces and avoid running noisy motor-drive traces adjacent to keep in-circuit debugging stable.
AVDD must be filtered through a ferrite bead or 10 ohm resistor from VDD, with a 10 uF + 100 nF cap stack right at the AVDD pin. This protects the ADC result register from digital switching noise on VDD. For motor-control designs where back-EMF signals share the analog rail, add a small RC low-pass (1 kohm + 100 nF) on each ANx input to attenuate PWM-edge ringing. Configure unused I/O pins as outputs to minimize Sleep-mode current draw.
Do not assume the PIC18F4539 (4.2-5.5 V) is interchangeable with the PIC18LF4539 (2.0-5.5 V) at 3.3 V operation - the F variant will fail to start. Verify the ordering code suffix ('LF' vs no 'L') before placing the part. Also, the 44-QFN land pattern differs from 44-QFP footprints; do not substitute a TQFP-44 footprint. Finally, when migrating from PIC18LF4523T-I/ML to PIC18LF4539T-I/ML check that the motor-control pin assignments match - the 4523 lacks the dedicated motor kernel pins.
Compliance Information
RoHS and REACH compliance per Microchip product page and distributor listings; industrial (-40C to +85C) temperature grade, not AEC-Q100 qualified (use automotive-grade PIC parts for vehicle applications).
