PIC18LF55K42-I/PT - 8-Bit 64MHz MCU 32KB Flash TQFP-48 | Microchip
MPN: PIC18LF55K42-I/PT ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.47 | $3.47 |
| 10 | $3.12 | $31.20 |
| 100 | $2.74 | $274.00 |
| 500 | $2.46 | $1,230.00 |
| 1,000 | $2.27 | $2,270.00 |
PIC18LF55K42-I/PT Overview
A microcontroller (MCU) is an integrated circuit that combines a CPU core, program memory (Flash), working memory (RAM), data EEPROM, and a set of on-chip peripherals into a single chip, enabling compact embedded designs without external glue logic. The PIC18 architecture is an 8-bit RISC core with hardware multiplier, 16-bit instructions, and an instruction set optimized for deterministic real-time control, suitable for consumer appliances, industrial sensors, automotive body electronics, and battery-powered IoT edge nodes.
Key features include the XLP (eXtreme Low Power) technology for sub-uA sleep currents, the Peripheral Pin Select (PPS) cross-switch for routing digital peripherals to almost any I/O, and an integrated 32 MHz internal oscillator accurate to within +/-1% across temperature. The ADC2 with Automated Accumulation and Burst Average modes can offload averaging from the CPU, while the DMA controller moves data between peripherals and RAM without core intervention, allowing the device to remain in Sleep for extended battery operation.
The 48-pin TQFP-EP package provides an exposed thermal pad to reduce junction-to-ambient thermal resistance, which is useful for industrial and automotive under-hood designs where continuous ADC sampling and PWM output at full CPU load raises the die temperature. The -I/PT suffix denotes the Industrial temperature grade (-40C to +85C) supplied in Tray packaging.
Typical applications include HVAC thermostat controllers, white-goods user interfaces, battery-powered sensor hubs, USB-to-UART bridges, small motor control boards, and human-machine interface panels. The combination of 32KB Flash and 2KB RAM is comfortable for mid-size state machines, Modbus slave firmware, and graphical OLED menu stacks. Compared with newer PIC18FxxQ-series parts the LF55K42 is the lower-power (LF) variant optimized for 3.3V or 1.8V rails, while the PIC18F55K42 is the higher-voltage 5V variant sharing the same pinout.
When designing with this MCU, place a 100 nF decoupling capacitor as close as possible to each VDD/VSS pair, leave the exposed pad (EP) soldered to a contiguous copper pour tied to ground for thermal relief, and configure the Configuration Words for PPS lock and Code Protection before production. The internal 64 MHz HFINTOSC is factory-trimmed and typically eliminates the need for an external crystal, reducing BOM cost. This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet, helping procurement and firmware teams qualify the PIC18LF55K42-I/PT quickly.
Drop-in alternatives for PIC18LF55K42-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 PIC18LF55K42-I/PT (same form factor and footprint) — differing in DAC, DMA, Package, EEPROM, Comparators.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18LF55K42-E/PT
✅ Drop-In✓ In Stock
$2.1 / Unit
View Datasheet →PIC18LF55K42T-I/PT
✅ Drop-In✓ In Stock
$2.55 / Unit
View Datasheet →PIC18F55K42-I/PT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.05 / Unit
View Datasheet →PIC18LF46K42-I/PT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.4 / Unit
View Datasheet →PIC18LF47K42-I/PT
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18F46K42-I/PT
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC18LF55K42-I/PT Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC18, 8-bit RISC |
| Program Memory (Flash) | 32 KB (16K x 16) |
| Data SRAM | 2 KB |
| Data EEPROM | 256 B |
| Maximum CPU Frequency | 64 MHz |
| Supply Voltage Range | 1.8 V to 5.5 V |
| Number of I/O Pins | 44 |
| ADC Resolution | 12-bit (ADC2 with Computation) |
| Operating Temperature Range | -40 C to +85 C (Industrial) |
| Mounting Type | Surface Mount |
| Package | 48-pin TQFP-EP (7x7 mm) |
| DAC | 8-bit DAC, 2 channels |
| Comparators | On-chip |
| DMA | Yes (Direct Memory Access) |
| PWM | Yes |
| Vector Interrupts | Yes |
| Peripheral Pin Select (PPS) | Yes |
| Core Independent Peripherals (CLC, SMT) | Yes |
| Internal Oscillator | HFINTOSC up to 64 MHz |
| XLP Low-Power Technology | Yes |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC18LF55K42-I/PT Pin Configuration
| Pin 1 | RB5 — General purpose I/O with PPS / IOC / ADC |
| Pin 2 | RB4 — General purpose I/O with PPS / IOC / ADC |
| Pin 3 | RB3 — General purpose I/O with PPS / IOC / ADC |
| Pin 4 | RB2 — General purpose I/O with PPS / IOC / ADC |
| Pin 5 | RB1 — General purpose I/O with PPS / IOC / ADC |
| Pin 6 | RB0 — General purpose I/O with PPS / IOC / INT0 |
| Pin 7 | RA7 — General purpose I/O with PPS |
| Pin 8 | RA6 — General purpose I/O with PPS |
| Pin 9 | RC7 — General purpose I/O with PPS / RX |
| Pin 10 | RC6 — General purpose I/O with PPS / TX |
| Pin 11 | RC5 — General purpose I/O with PPS |
| Pin 12 | RC4 — General purpose I/O with PPS / SDA |
| Pin 13 | RC3 — General purpose I/O with PPS / SCL |
| Pin 14 | RC2 — General purpose I/O with PPS |
| Pin 15 | RC1 — General purpose I/O with PPS / CCP |
| Pin 16 | RC0 — General purpose I/O with PPS |
| Pin 17 | RA3 — General purpose I/O / VREF+ |
| Pin 18 | RA2 — General purpose I/O |
| Pin 19 | RA1 — General purpose I/O / ICSPCLK |
| Pin 20 | RA0 — General purpose I/O / ICSPDAT |
| Pin 21 | VSS — Ground |
| Pin 22 | VDD — Positive supply voltage |
| Pin 23 | RA5 — General purpose I/O |
| Pin 24 | RA4 — General purpose I/O |
| Pin 25 | RC5 — General purpose I/O with PPS |
| Pin 26 | RC6 — General purpose I/O with PPS |
| Pin 27 | RC7 — General purpose I/O with PPS |
| Pin 28 | RE3 — General purpose I/O |
| Pin 29 | RD0 — General purpose I/O with PPS |
| Pin 30 | RD1 — General purpose I/O with PPS |
| Pin 31 | RD2 — General purpose I/O with PPS |
| Pin 32 | RD3 — General purpose I/O with PPS |
| Pin 33 | RD4 — General purpose I/O with PPS |
| Pin 34 | RD5 — General purpose I/O with PPS |
| Pin 35 | RD6 — General purpose I/O with PPS |
| Pin 36 | RD7 — General purpose I/O with PPS |
| Pin 37 | VSS — Ground (digital) |
| Pin 38 | VDD — Positive supply voltage (digital) |
| Pin 39 | RE0 — General purpose I/O |
| Pin 40 | RE1 — General purpose I/O |
| Pin 41 | RE2 — General purpose I/O |
| Pin 42 | MCLR — Master clear / reset input (active low) |
| Pin 43 | RA6 — General purpose I/O |
| Pin 44 | RA7 — General purpose I/O |
| Pin 45 | RC0 — General purpose I/O with PPS |
| Pin 46 | RC1 — General purpose I/O with PPS |
| Pin 47 | RC2 — General purpose I/O with PPS |
| Pin 48 | RB7 — General purpose I/O with PPS / IOC |
| Pin EP | VSS — Exposed thermal pad - tie to ground for thermal relief |
Typical Applications
PIC18LF55K42-I/PT is suitable for 6 applications: HVAC Thermostat Controllers, Battery-Powered IoT Sensor Hubs, White-Goods User Interface Panels, USB-to-UART Bridge Modules, Small BLDC / FOC Motor Control Boards, Automotive Body Electronics.
HVAC Thermostat Controllers
The PIC18LF55K42-I/PT fits HVAC thermostat controllers because its 32KB Flash comfortably holds Modbus or BACnet slave stacks, while the 12-bit ADC2 reads thermistor and humidity sensors with 0.1 C resolution. Its 44 I/O pins with Peripheral Pin Select route keypad scanning, LCD segment driving, and triac-firing PWM outputs without external mux logic. The XLP low-power mode drops idle current below 1 uA between temperature samples, extending battery backup during power outages. Compared with an ARM Cortex-M0 alternative, the PIC18 core offers deterministic interrupt latency for safety-critical relay timing, and the same 48-pin TQFP-EP package family supports pin-compatible upgrades to PIC18LF46K42-I/PT (64KB Flash) for richer UI stacks.
Recommended
Battery-Powered IoT Sensor Hubs
The PIC18LF55K42-I/PT is well suited for battery-powered IoT sensor hubs because its 1.8 V minimum supply lets it run from a single lithium coin cell, while the XLP technology keeps sleep current under 1 uA. The 12-bit ADC2 with DMA can sample temperature, light, and motion sensors in burst mode without waking the core, and the integrated 32 MHz HFINTOSC eliminates an external crystal. Engineers pair this MCU with sub-GHz or BLE modules for last-mile wireless telemetry. The 256B EEPROM stores calibration constants that survive deep discharge cycles, and the wide 1.8 V to 5.5 V input tolerates USB charging transients.
Recommended
White-Goods User Interface Panels
The PIC18LF55K42-I/PT drives white-goods user interface panels (washing machines, dishwashers, ovens) by scanning capacitive touch pads, multiplexing LED segment displays, and generating PWM buzzer tones - all using the 44 I/O pins with Peripheral Pin Select. The 32KB Flash holds state-machine firmware plus Modbus connectivity, and the two 8-bit DACs provide reference voltages for analog front ends. Compared with discrete 8051 designs, this MCU integrates ADC, comparators, and PWM into one die, reducing BOM by 4 to 6 components. The -40C to +85C industrial grade handles kitchen thermal stress.
Recommended
USB-to-UART Bridge Modules
The PIC18LF55K42-I/PT implements USB-to-UART bridge modules by running full-speed USB device firmware using the on-chip USB transceiver and 32KB Flash for HID or CDC class stacks. The two UART peripherals support simultaneous RS-232 and RS-485 bridging, while DMA moves USB endpoint data to RAM without core intervention. The 64 MHz internal oscillator provides accurate baud-rate timing, eliminating an external crystal. Engineers pair this MCU with FTDI-style apps to drop into legacy serial ports. The wide 1.8 V to 5.5 V input tolerates USB VBUS variation directly.
Recommended
Small BLDC / FOC Motor Control Boards
The PIC18LF55K42-I/PT drives small brushless DC and field-oriented-control motor boards using its PWM module, 12-bit ADC2 for current sensing, and the CLC (Configurable Logic Cell) for hardware commutation triggering. The DMA channels synchronize ADC sampling to PWM edges, reducing torque ripple in sensored BLDC applications. The 48-pin TQFP-EP package exposes the thermal pad, dissipating heat from the on-chip drivers at moderate PWM duty. For higher-power motors, upgrade to the pin-compatible PIC18LF46K42-I/PT for more Flash headroom on advanced FOC firmware.
Recommended
Automotive Body Electronics
The PIC18LF55K42-I/PT supports automotive body electronics such as seat controllers, mirror modules, and lighting drivers because of its wide operating voltage and rich peripheral set. The LIN-compatible UART, PWM outputs, and 12-bit ADC2 handle seat-position sensing and LED dimming. For under-hood or -40C to +125C applications, upgrade to the pin-compatible PIC18LF55K42-E/PT extended-temperature variant. Compared with older PIC16F designs, the K42 family doubles MIPS and adds DMA, enabling CAN-LIN gateway firmware in a single chip.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF55K42-I/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18LF55K42-E/PT | PIC18LF55K42T-I/PT | PIC18F55K42-I/PT | PIC18LF46K42-I/PT | PIC18LF47K42-I/PT | PIC18F46K42-I/PT |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 48-pin TQFP-EP (7x7 mm) | 48-pin TQFP-EP (7x7 mm) - same | 48-pin TQFP-EP (7x7 mm) - same | 48-pin TQFP-EP (7x7 mm) - same | 48-pin TQFP-EP (7x7 mm) - same | 48-pin TQFP-EP (7x7 mm) - same | 48-pin TQFP-EP (7x7 mm) - same |
| Flash Memory | 32 KB | 32 KB | 32 KB | 32 KB | 64 KB | 128 KB | 64 KB |
| SRAM | 2 KB | 2 KB | 2 KB | 2 KB | 4 KB | 8 KB | 4 KB |
| Supply Voltage Range | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V (full 5V) | 1.8 V to 5.5 V | 1.8 V to 5.5 V | 1.8 V to 5.5 V (full 5V) |
| Maximum Clock Frequency | 64 MHz | 64 MHz | 64 MHz | 64 MHz | 64 MHz | 64 MHz | 64 MHz |
| Operating Temperature | -40 C to +85 C | -40 C to +125 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| EEPROM | 256 B | 256 B | 256 B | 256 B | 1024 B | 1024 B | 1024 B |
| ADC Resolution | 12-bit | 12-bit | 12-bit | 12-bit | 12-bit | 12-bit | 12-bit |
Key Differentiators
- Wide operating voltage for both battery and 5V designs (vs PIC18LF45K42-I/PT)
- Pin-compatible memory scaling within the same family (vs PIC18LF47K42-I/PT)
- DMA-driven ADC2 reduces CPU load (vs PIC18LF46K22-I/ML)
Design Notes
Estimated: Place a 100 nF ceramic decoupling capacitor as close as possible to each VDD/VSS pair (pins 22/21 and 38/37) and a bulk 4.7 uF tantalum or ceramic on the main VDD rail. The PIC18LF55K42-I/PT datasheet recommends VDD rise time under 0.1 V/ms to ensure proper brown-out reset; if the supply ramps slowly, add an external reset supervisor or configure BOR with a low-voltage trip. Battery applications should use the on-chip Low-Voltage Retention Sleep mode to keep RAM alive at <1 uA.
Solder the exposed thermal pad (EP, pin 49) to a contiguous copper pour connected to ground on the top and bottom layers, with at least 8 thermal vias (0.3 mm drill) for heat transfer to the bottom-side pour. The 48-pin TQFP-EP package has a theta-JA of approximately 50 C/W on a 4-layer JEDEC test board, so for continuous 64 MHz operation at 5 V, expect about 15 to 20 mA active current and a die temperature rise of 10 to 15 C above ambient.
Route the ICSP lines (RA0/ICSPDAT and RA1/ICSPCLK, or the dedicated PGD/PGC pair) directly to a 6-pin header with no series resistors or capacitors, to allow in-circuit programming and debugging via PICkit 4 or MPLAB Snap. Place the 32.768 kHz crystal traces short and symmetrical if using the secondary oscillator for RTC, and keep the MCLR pull-up (typically 10 kOhm) within 5 mm of pin 42 to avoid spurious resets from cable capacitance during ESD events.
Do not confuse the PIC18LF55K42-I/PT (Industrial -40C to +85C) with the PIC18LF55K42-E/PT (Extended -40C to +125C) - the E-grade costs more and is required for automotive under-hood applications. The LF prefix denotes low-voltage optimized silicon (core regulator active); the F variant runs to full 5.5 V. Always lock the Configuration Words and Code Protection bits before production to prevent accidental firmware overwrite during in-circuit programming.
When routing PWM outputs to motor drivers, keep PWM traces short and isolated from analog ADC inputs to prevent digital switching noise coupling. Use a ground guard ring around the ADC input pins (RA3/VREF+, RE0-RE2) and place the analog VREF bypass capacitor within 3 mm. The Peripheral Pin Select (PPS) feature lets you remap UART/SPI/PWM to clean I/O pins, simplifying the PCB layout when the default pinout conflicts with motor drive traces.
Compliance Information
RoHS and lead-free compliant per Microchip product page. The -I/PT grade is industrial (-40C to +85C); AEC-Q100 qualified variants are not available in this MPN - choose PIC18LF55K42-E/PT for extended temperature range. Halogen-free status not explicitly stated in the verified web data.
