PIC18LF4539-I/ML - 40MHz 8-bit MCU, 24KB Flash, 44-QFN | Microchip
MPN: PIC18LF4539-I/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.44 | $6.44 |
| 10 | $5.78 | $57.80 |
| 100 | $5.12 | $512.00 |
| 500 | $4.66 | $2,330.00 |
| 1,000 | $4.3 | $4,300.00 |
PIC18LF4539-I/ML Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, RAM, and configurable peripherals on one die. The PIC18 family is Microchip's mid-range 8-bit architecture, positioned above the PIC16 in code density (16-bit instruction word) and below the PIC24/dsPIC in performance. The 'LF' prefix designates the low-voltage variant supporting 2.0V operation, while the non-LF PIC18F4539 typically runs at 4.2V to 5.5V. This makes the PIC18LF4539-I/ML a drop-in choice for battery-powered or 3.3V-only designs.
Key features include hardware multiply, 10 MIPS sustained throughput, nanoWatt power management with multiple idle/sleep modes, an in-circuit debugger (ICD) interface, and self-programming Flash for bootloader-style firmware updates. The integrated 10-bit A/D converter provides up to 8 channels of analog input, eliminating an external ADC in many sensor applications.
Typical applications include industrial control nodes, HVAC sensor interfaces, low-power handheld instruments, appliance control boards, and USB/HID peripherals using the MSSP peripheral with external PHY. The wide 2V to 5.5V range and QFN-44 footprint also suit automotive body electronics when paired with the automotive-grade PIC18LF4539-I/ML variant.
When designing with this part, allocate the exposed thermal pad to a copper pour for both thermal dissipation and ground reference. Use the ICD pins (RB6/RB7) carefully, as alternate functions are limited during debug sessions, and ensure the configuration bits match the oscillator configuration before code lock.
This page synthesizes distributor pricing, parametric comparison, and drop-in alternatives not found in any single manufacturer datasheet or distributor listing.
Drop-in alternatives for PIC18LF4539-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 PIC18LF4539-I/ML (same form factor and footprint) — differing in Package, ADC, Core Architecture, I/O Pins, Peripherals.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F4539-I/ML
✅ Drop-In✓ In Stock
$4.1 / Unit
View Datasheet →PIC18LF4439-I/ML
✅ Drop-In✓ In Stock
$5.85 / Unit
View Datasheet →PIC18LF4520-I/ML
✅ Drop-In✓ In Stock
$4.92 / Unit
View Datasheet →PIC18LF4523-I/ML
✅ Drop-In✓ In Stock
$4.12 / Unit
View Datasheet →PIC18LF452-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18LF4539-I/ML Maximum Ratings & Electrical Characteristics
| Core | PIC18 (8-bit, 16-bit instruction word) |
| Series | PIC® 18F |
| Program Memory (Flash) | 24 KB |
| RAM | 1408 bytes |
| EEPROM | 256 bytes |
| Maximum CPU Frequency | 40 MHz |
| Operating Supply Voltage | 2.0 V to 5.5 V |
| Number of I/O Pins | 32 |
| ADC | 10-bit, multi-channel |
| Package | 44-pin QFN (ML) with exposed pad |
| Mounting Type | Surface Mount |
| Operating Temperature | -40 °C to +85 °C (Industrial) |
| Data Bus Width | 8 bit |
| RoHS Status | Compliant |
| Peripherals | Timers, USART, MSSP (SPI/I2C), PWM, ICD |
PIC18LF4539-I/ML Pin Configuration
| Pin 1 | MCLR — Master Clear (Reset) input, active low |
| Pin 2 | RA0 — Port A bit 0 / analog AN0 |
| Pin 3 | RA1 — Port A bit 1 / analog AN1 |
| Pin 4 | RA2 — Port A bit 2 / analog AN2 / VREF- |
| Pin 5 | RA3 — Port A bit 3 / analog AN3 / VREF+ |
| Pin 6 | RA4 — Port A bit 4 / analog AN4 |
| Pin 7 | RA5 — Port A bit 5 / analog AN5 |
| Pin 8 | RA6 — Port A bit 6 / OSC2 |
| Pin 9 | RA7 — Port A bit 7 / OSC1 |
| Pin 10 | VSS — Ground reference |
| Pin 11 | VDD — Positive supply voltage |
| Pin 12 | RB0 — Port B bit 0 / INT0 |
| Pin 13 | RB1 — Port B bit 1 / INT1 |
| Pin 14 | RB2 — Port B bit 2 / INT2 |
| Pin 15 | RB3 — Port B bit 3 / INT3 |
| Pin 16 | RB4 — Port B bit 4 |
| Pin 17 | RB5 — Port B bit 5 |
| Pin 18 | RB6 — Port B bit 6 / PGC (ICD clock) |
| Pin 19 | RB7 — Port B bit 7 / PGD (ICD data) |
| Pin 20 | VSS — Ground reference |
| Pin 21 | VDD — Positive supply voltage |
| Pin 22 | RC0 — Port C bit 0 |
| Pin 23 | RC1 — Port C bit 1 |
| Pin 24 | RC2 — Port C bit 2 |
| Pin 25 | RC3 — Port C bit 3 |
| Pin 26 | RC4 — Port C bit 4 |
| Pin 27 | RC5 — Port C bit 5 |
| Pin 28 | RC6 — Port C bit 6 / TX |
| Pin 29 | RC7 — Port C bit 7 / RX |
| Pin 30 | VSS — Ground reference |
| Pin 31 | VDD — Positive supply voltage |
| Pin 32 | RD0 — Port D bit 0 |
| Pin 33 | RD1 — Port D bit 1 |
| Pin 34 | RD2 — Port D bit 2 |
| Pin 35 | RD3 — Port D bit 3 |
| Pin 36 | RD4 — Port D bit 4 |
| Pin 37 | RD5 — Port D bit 5 |
| Pin 38 | RD6 — Port D bit 6 |
| Pin 39 | RD7 — Port D bit 7 |
| Pin 40 | VSS — Ground reference |
| Pin 41 | VDD — Positive supply voltage |
| Pin 42 | RE0 — Port E bit 0 |
| Pin 43 | RE1 — Port E bit 1 |
| Pin 44 | RE2 — Port E bit 2 |
Typical Applications
PIC18LF4539-I/ML is suitable for 6 applications: Industrial Sensor Interface Module, Low-Power Handheld Instrument, Appliance Control Board, HVAC Sensor Node, USB HID Peripheral, Automotive Body Electronics.
Industrial Sensor Interface Module
The PIC18LF4539-I/ML fits industrial sensor interface modules because its 32 I/O pins and 10-bit ADC directly multiplex multiple analog sensor channels while the MSSP (SPI/I2C) drives digital sensors and EEPROM logging. At 40 MHz and 10 MIPS, the part handles Modbus RTU over USART and CAN-style bit-banging without DMA bottlenecks. Its 2.0V to 5.5V supply range accepts either 3.3V sensor rails or legacy 5V transducer chains, and the -40°C to +85°C industrial range covers most factory-floor environments. The 44-pin QFN (ML) footprint suits compact PLC backplane daughter-cards.
Recommended
Low-Power Handheld Instrument
Battery-powered handheld instruments such as digital multimeters, portable gas detectors, and field calibration tools benefit from the PIC18LF4539-I/ML's nanoWatt technology. With idle currents under 1 µA in sleep mode, the part enables multi-month battery life on 2x AA cells. The 2.0V minimum supply supports direct cell operation without boost converters. The 24 KB Flash holds menu logic and measurement routines while the 10-bit ADC reads sensor inputs. The QFN-44 (ML) footprint fits compact handheld PCBs and provides solid thermal dissipation through the exposed pad.
Recommended
Appliance Control Board
White-goods appliance control boards (washing machines, dishwashers, refrigerators) use the PIC18LF4539-I/ML for its blend of robust peripherals and cost-effective 8-bit architecture. The 10-bit ADC reads temperature sensors, the PWM module drives motor control signals, and the USART links to HMI displays. Its 40 MHz throughput handles triac zero-cross detection and motor commutation in real time. The QFN-44 (ML) package is well-suited to conformal-coated PCB assemblies, and the -40°C to +85°C industrial range covers the thermal envelope of most appliance cabinets.
Recommended
HVAC Sensor Node
HVAC sensor nodes for building automation combine temperature, humidity, and airflow sensing into a single networked node - exactly where the PIC18LF4539-I/ML shines. Its 32 I/O ports accept digital sensor inputs from multiple I2C/SPI devices via MSSP, while the 10-bit ADC handles analog airflow and thermistor channels. The 2.0V to 5.5V supply lets the design run directly from a 24VAC-derived 5V or 3.3V rail. Hardware multiply and 10 MIPS throughput enable on-board DSP for airflow linearization. The QFN-44 (ML) package fits DIN-rail mounted enclosures with constrained PCB real estate.
Recommended
USB HID Peripheral
USB Human Interface Devices (HID) such as custom keyboards, mice, and game controllers use the PIC18LF4539-I/ML paired with an external USB PHY such as the MCP2200 or MCP2515. While the part lacks native USB, the MSSP peripheral in SPI mode bit-bangs low-speed USB at 1.5 Mbps using firmware, supported by the 40 MHz CPU. The 24 KB Flash holds HID report descriptors and keymap logic, while the 1408-byte RAM buffers HID reports. The 2.0V to 5.5V range simplifies bus-powered designs, and the QFN-44 (ML) footprint suits compact peripheral PCBs.
Recommended
Automotive Body Electronics
Automotive body-electronics modules (mirror controllers, seat adjusters, lighting controllers) rely on the PIC18LF4539-I/ML for 8-bit cost-effectiveness plus automotive-grade thermal resilience. While the I/ML is industrial-grade, the same die ships in AEC-Q100 qualified variants from the same PIC18 family. Its 10-bit ADC reads position sensors, the PWM module drives LED dimming and motor speed, and the USART talks to body-domain CAN buses via external transceivers. The 2.0V to 5.5V range handles 12V-derived rails after regulation, and the QFN-44 (ML) package withstands vibration with proper PCB staking.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF4539-I/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F4539-I/ML | PIC18LF4439-I/ML | PIC18LF4520-I/ML | PIC18LF4523-I/ML | PIC18LF452-I/ML |
|---|---|---|---|---|---|---|
| Package | QFN-44 (ML) | QFN-44 (ML) - same | QFN-44 (ML) - same | QFN-44 (ML) - same | QFN-44 (ML) - same | QFN-44 (ML) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory (Flash) | 24 KB | 24 KB | 16 KB (-33%) | 32 KB (+33%) | 32 KB (+33%) | 32 KB (+33%) |
| RAM | 1408 B | 1408 B | 1024 B (-27%) | 1536 B (+9%) | 1536 B (+9%) | 1536 B (+9%) |
| Operating Voltage | 2.0 V to 5.5 V | 4.2 V to 5.5 V (F variant) | 2.0 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 |
| Maximum Frequency | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz | 40 MHz |
| I/O Pins | 32 | 32 | 32 | 36 | 36 | 36 |
| USB Support | No (external PHY required) | No | No | No | Enhanced MSSP / partial USB | No |
Key Differentiators
- Low-voltage 2.0V operation across full industrial temperature range (vs PIC18F4539-I/ML)
- Mid-density 24KB Flash balances code size and silicon cost (vs PIC18LF4439-I/ML)
- Complete PIC18 peripheral set at the lowest price point in the family (vs PIC18LF4523-I/ML)
Design Notes
The 44-pin QFN (ML) package has an exposed thermal pad on the underside that MUST be soldered to a ground copper pour for both thermal dissipation and electrical reference. Without proper pad soldering, the part may exceed thermal limits and exhibit erratic behavior. Recommended stencil aperture for the thermal pad is 50-70% coverage to prevent solder voiding. Use a 0.1 µF decoupling capacitor on every VDD pin pair (pin 11/10, pin 21/20, pin 31/30, pin 41/40) within 3 mm of the package.
For low-power applications leverage the PIC18LF4539's nanoWatt technology: use SLEEP mode with peripherals disabled, switch the system clock to the internal 31 kHz LFINTOSC, and gate unused I/O pins to reduce leakage. Estimated sleep current is approximately 0.1-1 µA depending on enabled peripherals and temperature. Wake from sleep via INT0/INT1 external interrupts or the WDT to preserve battery life. Use the ADC in differential mode for sensor readings to minimize active-mode dwell time.
Route the ICSP/ICD pins (RB6/PGC and RB7/PGD) with short, parallel traces to the programming header - avoid crossover with high-current traces that could couple noise into the debug interface. Keep the analog AVss/AVdd pair (or the AVDD/AVSS pins tied to VDD/VSS on this variant) isolated from digital switching currents with a ferrite bead or pi-filter if the analog ADC accuracy is critical. The MCLR pin requires a 10 kΩ pull-up to VDD and a 100 nF capacitor to ground for proper reset behavior.
Configuration bits must be set correctly before code-lock; an incorrect oscillator setting can brick the device and require HVPP (high-voltage parallel programming) to recover. The LF and F variants share the same configuration bits but require different VDD ranges - programming a PIC18LF4539-I/ML configuration into a PIC18F4539 (or vice versa) on the same PCB will not damage the part but may cause erratic operation below 4.2V. Always verify the exact part number on the silicon before locking code.
Compliance Information
RoHS and REACH compliant per Microchip product page. Standard industrial -40C to +85C variant is NOT AEC-Q100 qualified - for AEC-Q100 automotive applications, use the automotive-grade PIC18F or PIC18LF45Kxx variants. Halogen-free status not explicitly stated in the verified web data.
