PIC18LF4539-I/PT - 8-Bit 40MHz 24KB Flash MCU TQFP-44 | Microchip
MPN: PIC18LF4539-I/PT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.54 | $7.54 |
| 10 | $6.79 | $67.90 |
| 100 | $5.83 | $583.00 |
| 500 | $5.12 | $2,560.00 |
| 1,000 | $4.1 | $4,100.00 |
PIC18LF4539-I/PT Overview
A microcontroller (MCU) is a single-chip computer containing a CPU core, program memory, data memory, peripherals, and I/O ports. The PIC18 family is Microchip's enhanced 8-bit RISC architecture, featuring a 16-bit instruction word, hardware multiplier, linear program memory up to 2 MB, and prioritised interrupt controller. PIC18 parts sit above baseline PIC16 devices in the taxonomy (PIC microcontroller -> 8-bit MCU -> microcontroller -> embedded computing IC), and are commonly used as the main system controller in cost-sensitive embedded products where a 32-bit Cortex-M0/M0+ would be overkill.
Key features of the PIC18LF4539 include 32 bidirectional digital I/O pins, an integrated 12-bit ADC (A/D) converter, multiple timers, a USART, MSSP (SPI / I2C), and a dual-channel capture/compare/PWM module. The internal oscillator block supports 31 kHz to 8 MHz operation with PLL up to 40 MHz. Enhanced Flash with self-programmability supports in-application updates. The PIC18LF variant in particular targets low-voltage / battery-powered systems, retaining full performance at 2.0 V.
Architecturally, the PIC18LF4539 uses an advanced Harvard RISC core with 16-bit instructions and 8-bit data path, plus a hardware multiplier for fast signed/unsigned operations. The enhanced Flash controller supports single-cycle accesses and ICSP (In-Circuit Serial Programming), allowing firmware updates without removing the part from the PCB. The device also integrates nanoWatt technology modes that drop supply current to the microamp range during sleep, making it suitable for battery-powered sensor nodes.
Typical applications include industrial automation and control, low-power remote sensor nodes, USB peripherals (USB-capable variant), motor control, white-goods appliance controllers, instrumentation front-ends, and general-purpose embedded control in 3.3 V systems. For designs moving to newer silicon, the PIC18F46K22, PIC18F46J50, and PIC18F47J53 in the same TQFP-44 footprint offer modern peripherals (XLP, CTMU, RTCC) at lower cost and broader availability.
When designing with this part, observe the 2.0 V minimum supply for full 40 MHz operation only with the 'LF' suffix; verify brown-out reset and watchdog timing for your application, and choose external vs. internal oscillator based on timing accuracy needs. The 44-pin TQFP provides an upgrade path to modern PIC18 K-series and J-series parts in the same footprint.
This page synthesises distributor pricing, parametric drops-in same-package alternatives, and practical design notes that are not present in the manufacturer datasheet, giving engineers a single source for sourcing and substitution decisions on the PIC18LF4539-I/PT.
Drop-in alternatives for PIC18LF4539-I/PT — 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/PT (same form factor and footprint) — differing in Core Architecture, Package, Operating Temperature, ADC, I/O Pins.
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Request AlternativesPIC18LF4539-I/PT Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC RISC 8-bit |
| Family | PIC18F |
| Program Memory Size | 24 KB (12K x 16) Flash |
| RAM Size | 1408 bytes |
| EEPROM Size | 256 bytes |
| Maximum CPU Speed | 40 MHz (10 MIPS) |
| Supply Voltage Range | 2.0 V to 5.5 V |
| I/O Pins | 32 (some sources report 33-34) |
| Operating Temperature | -40C to +85C (Industrial) |
| Package | 44-TQFP (PT) 10x10 mm |
| ADC | 10/12-bit A/D converter |
| Timers | Multiple 8-bit and 16-bit timers |
| Communication | USART, MSSP (SPI / I2C) |
| Mounting Style | Surface Mount |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC18LF4539-I/PT Pin Configuration
| Pin 1 | RB2 — Digital I/O port B bit 2 / INT2 |
| Pin 2 | RB3 — Digital I/O port B bit 3 / CCP2 |
| Pin 3 | RB4 — Digital I/O port B bit 4 |
| Pin 4 | RB5 — Digital I/O port B bit 5 / PGM |
| Pin 5 | RB6 — Digital I/O port B bit 6 / PGC (ICSP clock) |
| Pin 6 | RB7 — Digital I/O port B bit 7 / PGD (ICSP data) |
| Pin 7 | VSS — Ground reference |
| Pin 8 | VDD — Positive supply (2.0 V to 5.5 V) |
| Pin 9 | RA0 — Digital I/O / analogue AN0 |
| Pin 10 | RA1 — Digital I/O / analogue AN1 |
| Pin 11 | RA2 — Digital I/O / analogue AN2 / VREF- |
| Pin 12 | RA3 — Digital I/O / analogue AN3 / VREF+ |
| Pin 13 | RA4 — Digital I/O / T0CKI (Timer0 clock) |
| Pin 14 | RA5 — Digital I/O / analogue AN4 / SS |
| Pin 15 | RE0 — Digital I/O port E bit 0 / RD |
| Pin 16 | RE1 — Digital I/O port E bit 1 / WR |
| Pin 17 | RE2 — Digital I/O port E bit 2 / CS |
| Pin 18 | VDD — Positive supply |
| Pin 19 | VSS — Ground |
| Pin 20 | OSC1 — Oscillator input / CLKIN |
| Pin 21 | OSC2 — Oscillator output / CLKOUT |
| Pin 22 | RC0 — Digital I/O port C bit 0 / T1OSO |
| Pin 23 | RC1 — Digital I/O port C bit 1 / T1OSI / CCP2 |
| Pin 24 | RC2 — Digital I/O port C bit 2 / CCP1 |
| Pin 25 | RC3 — Digital I/O port C bit 3 / SCL |
| Pin 26 | RC4 — Digital I/O port C bit 4 / SDI |
| Pin 27 | RC5 — Digital I/O port C bit 5 / SDO |
| Pin 28 | RC6 — Digital I/O port C bit 6 / TX |
| Pin 29 | RC7 — Digital I/O port C bit 7 / RX |
| Pin 30 | RB0 — Digital I/O port B bit 0 / INT0 |
| Pin 31 | RB1 — Digital I/O port B bit 1 / INT1 |
| Pin 32 | MCLR — Master clear reset (active-low) |
| Pin 33 | RD0 — Digital I/O port D bit 0 / PSP0 |
| Pin 34 | RD1 — Digital I/O port D bit 1 / PSP1 |
| Pin 35 | RD2 — Digital I/O port D bit 2 / PSP2 |
| Pin 36 | RD3 — Digital I/O port D bit 3 / PSP3 |
| Pin 37 | RD4 — Digital I/O port D bit 4 / PSP4 |
| Pin 38 | RD5 — Digital I/O port D bit 5 / PSP5 |
| Pin 39 | RD6 — Digital I/O port D bit 6 / PSP6 |
| Pin 40 | RD7 — Digital I/O port D bit 7 / PSP7 |
| Pin 41 | VSS — Ground |
| Pin 42 | AVSS — Analogue ground |
| Pin 43 | AVDD — Analogue positive supply |
| Pin 44 | NC — Not connected (per datasheet) |
Typical Applications
PIC18LF4539-I/PT is suitable for 6 applications: Industrial Automation Controllers, Low-Power Remote Sensor Nodes, White-Goods Appliance Control, Instrumentation Front-End Controllers, General-Purpose 3.3 V Embedded Control, Educational / Development Platforms.
Industrial Automation Controllers
The PIC18LF4539-I/PT suits industrial PLC and automation I/O modules thanks to its 2.0 V to 5.5 V operating range, 32 digital I/O pins, and 24 KB Flash supporting ladder-logic or state-machine firmware. Its USART and MSSP (SPI / I2C) interfaces connect to sensor buses and HMI displays, while the 10/12-bit ADC reads analogue process variables such as temperature or pressure. Industrial-grade -40C to +85C operation and nanoWatt sleep modes also allow battery-backed remote terminal units. For new designs, the PIC18F46K22-I/PT in the same TQFP-44 footprint offers more memory and on-chip peripherals; the PIC18LF4539-I/PT remains a strong fit for legacy firmware migration and field-replacement of installed equipment.
Recommended
Low-Power Remote Sensor Nodes
The PIC18LF4539-I/PT's nanoWatt Technology sleep modes (down to microamp-range Iq) and 2.0 V minimum supply make it viable for battery-powered wireless sensor nodes transmitting periodic readings over SPI or UART. With internal RC oscillator and idle/peripheral sleep modes, average current can be held under 100 uA in 1 percent duty-cycle wake cycles. The 24 KB Flash hosts sensor fusion and protocol stacks, while the 10/12-bit ADC digitises analogue sensors directly. For new ultra-low-power nodes, the PIC18LF46K22-I/PT (XLP, nanoamp-range sleep) in the same TQFP-44 package is preferred, but the LF4539 remains serviceable for existing designs and field-repairs.
Recommended
White-Goods Appliance Control
The PIC18LF4539-I/PT is well-suited to white-goods appliance controllers (washing machines, dishwashers, microwave ovens, refrigerators) because of its 5 V tolerance, 32 I/O pins for keypad/LED/relay drive, and CCP/PWM modules for motor and triac control. The 24 KB Flash supports UI state machines and safety logic, while USART links to inverter boards and diagnostic ports. nanoWatt modes drop standby current when the appliance is idle. The PIC18F46K22-I/PT in the same TQFP-44 footprint is recommended for new designs (more Flash, RTCC for scheduling, lower cost). The LF4539 is widely used in installed white-goods generations and remains in service for repairs.
Recommended
Instrumentation Front-End Controllers
In bench-top and field instrumentation (multimeters, calibrators, dataloggers), the PIC18LF4539-I/PT acts as the main controller because of its 2.0 V to 5.5 V supply, 24 KB Flash for menu/calibration firmware, USART for PC link, and 10/12-bit ADC for direct sensor digitisation. The TQFP-44 footprint provides adequate I/O for LCD, keypad, and relay outputs. With proper PCB layout, the PIC18LF4539-I/PT's noise immunity supports LSB-stable digitisation of low-level signals. New designs benefit from PIC18F46K22-I/PT's larger memory, but the LF4539 is field-proven for measurement electronics.
Recommended
General-Purpose 3.3 V Embedded Control
The PIC18LF4539-I/PT serves as a versatile general-purpose MCU for 3.3 V embedded control boards, where its 2.0 V minimum supply, 40 MHz CPU, USART/SPI/I2C peripherals, and 32 I/O pins cover most hobbyist and OEM prototype needs. It programs via ICSP through the standard PGD/PGC pins without external components, simplifying bring-up. The TQFP-44 10x10 mm package is easy to hand-solder or breadboard. For new designs, PIC18F46K22-I/PT or PIC18F46J50-I/PT in the same package are recommended; the LF4539 remains a fine choice for code-compat designs and educational kits.
Recommended
Educational / Development Platforms
The PIC18LF4539-I/PT is often used on PIC development boards, training kits, and university course material because it integrates enough peripherals (ADC, timers, USART, MSSP) for full curriculum coverage while fitting a breadboard-friendly TQFP-44 footprint. MPLAB X IDE and the XC8 compiler provide free firmware toolchains. The wide 2.0 V to 5.5 V range lets students experiment with 3.3 V and 5 V peripherals without level translation. The PIC18F46K22-I/PT is now preferred for new curricula (more memory, free samples), but the LF4539 continues to ship on many educational platforms.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF4539-I/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18LF4539-I/ML |
|---|---|---|
| Brand | Microchip Technology | Microchip Technology |
| Package | TQFP-44 (PT) 10x10 mm | QFN-44 (ML) 8x8 mm - DIFFERENT footprint |
| Program Memory | 24 KB Flash | 24 KB Flash |
| RAM | 1408 bytes | 1408 bytes |
| Maximum CPU Speed | 40 MHz (10 MIPS) | 40 MHz (10 MIPS) |
| Supply Voltage Range | 2.0 V to 5.5 V | 2.0 V to 5.5 V |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C (Industrial) |
| I/O Pins | 32-34 | 32-34 |
| Lifecycle / Status | Active (Legacy) | Active (Legacy) |
| RoHS Compliance | Compliant | Compliant |
Key Differentiators
- TQFP-44 10x10 mm industrial-grade package with wide 2.0 V to 5.5 V supply (vs PIC18F46J50-I/PT (same TQFP-44 footprint))
- 24 KB Flash with 256 bytes EEPROM in TQFP-44 footprint (vs PIC18LF46K22-I/PT (TQFP-44))
- nanoWatt Technology with 2.0 V to 5.5 V range (vs PIC18F46J50-I/PT (TQFP-44))
Design Notes
The PIC18LF4539-I/PT operates from 2.0 V to 5.5 V; for full 40 MHz operation, VDD must be 4.2 V or above (verify exact threshold in the manufacturer datasheet). Decouple VDD/AVDD with 100 nF ceramic placed within 5 mm of each pin pair, plus a bulk 10 uF tantalum or aluminium-polymer capacitor. The LF variant supports nanoWatt sleep modes that drop Iq into the microamp range when the CPU is halted and peripherals gated off - use these for battery duty-cycling.
TQFP-44 10x10 mm requires 0.8 mm pitch traces; use 0.2 mm trace width with 0.2 mm clearance, and ensure ground pour covers the entire underside for thermal dissipation and EMI control. Place the ICSP header (PGD/PGC/MCLR/VSS/VDD) on a 0.1 inch (2.54 mm) pitch 5-pin connector for in-circuit programming and debug. Avoid routing analogue (RA/AN) traces near switching traces to preserve ADC accuracy.
Do not assume 32 I/O pins are simultaneously available - many pins share analogue inputs (AN), timer clocks (T0CKI/T1OSI), or peripheral outputs (CCP/SPI/UART), so check the pin-function priority table in the manufacturer datasheet before finalising schematic. The MCLR pin must have a 10 kohm pull-up to VDD; omitting it prevents normal startup. Brown-out reset (BOR) and watchdog (WDT) must be configured via configuration bits before code can disable them in firmware.
For 40 MHz operation with the internal oscillator, place the OSC1/OSC2 crystal (if used) within 5 mm of the MCU with short, symmetric traces and a ground guard ring. The internal PLL is sensitive to supply ripple; keep the VDD trace impedance low and avoid sharing decoupling with high-current switching loads. For SPI buses above 5 MHz, add 33 ohm series resistors at the source pins to dampen reflections.
Compliance Information
RoHS and REACH compliance per Microchip product declaration; lead-free TQFP package per JEDEC J-STD-020. Not AEC-Q100 qualified (consumer/industrial grade). For automotive applications, use PIC18F46K22-I/PT (AEC-Q100) instead. Halogen-free status not explicitly stated in web data; refer to Microchip PCN for confirmation.