PIC18LF27K40-I/SS - 128KB Flash 8-bit MCU, XLP | Microchip
MPN: PIC18LF27K40-I/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.2 | $4.20 |
| 10 | $3.75 | $37.50 |
| 100 | $3.3 | $330.00 |
| 500 | $2.9 | $1,450.00 |
| 1,000 | $2.55 | $2,550.00 |
PIC18LF27K40-I/SS Overview
The term MCU stands for Microcontroller Unit, a single-chip computer containing a CPU core, memory, and programmable input/output peripherals. The PIC18 family sits within Microchip's 8-bit microcontroller portfolio, which favors deterministic instruction execution, low power consumption, and ease of use. Within this family, the LF prefix denotes a wide-voltage variant supporting 1.8 V to 3.6 V operation, while the absence of F (PIC18F27K40) marks a 2.0 V to 5.5 V range. Both belong to the broader K40 sub-family designed for Xtreme Low Power (XLP) applications.
Key features of the PIC18LF27K40-I/SS include a 10-bit ADC with Computation (ADCC) supporting automated Capacitive Voltage Divider (CVD) techniques for touch sensing, a 5-bit DAC, two comparators, a Complementary Waveform Generator (CWG), PWM modules, CCP modules, a Windowed Watchdog Timer (WWDT), CRC/SCAN memory scanners, and a Zero-Cross Detect (ZCD) peripheral. The integrated Core Independent Peripherals allow deterministic hardware-driven tasks without CPU intervention, reducing firmware complexity and power consumption. Two I2C, two SPI, and two UART interfaces support common wired communication needs.
The device's 64 MHz internal oscillator combined with XLP nanWatt technology achieves typical sleep currents below 50 nA, making it suitable for battery-powered sensors that must operate for years on a single cell. With 128 KB of Flash, the PIC18LF27K40 can host over-the-air update bootloaders, USB stacks (CDC/HID), or display-rich user interfaces while leaving headroom for application logic. CIP peripherals such as the CWG enable hardware-driven motor control, while the ADCC simplifies touch and sensor acquisition without CPU wakeup.
Typical applications include consumer and industrial IoT sensor nodes, capacitive touch user interfaces, battery-powered remote controls, home automation controllers, low-power metering, and small motor/pump drivers. Designers appreciate the LF voltage range when powering directly from a single lithium coin cell.
When designing with the PIC18LF27K40-I/SS, ensure that supply voltage stays within the LF window of 1.8 V to 3.6 V; for 5 V rails, choose the PIC18F27K40-I/SS instead. Decouple VDD with a 100 nF ceramic capacitor placed within 5 mm of the pin. Configure unused I/O as digital outputs low to minimize transient current. According to the Microchip datasheet, programming and debugging rely on the standard ICSP interface via PGC/PGD.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC18LF27K40-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 PIC18LF27K40-I/SS (same form factor and footprint) — differing in ADC, Comparators, Package, Operating Temperature, EEPROM.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F27K40-I/SS
✅ Drop-In✓ In Stock
$1.99 / Unit
View Datasheet →PIC18LF26K40-I/SS
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC18F26K40-I/SS
✅ Drop-In✓ In Stock
$1.32 / Unit
View Datasheet →PIC18LF27K40-I/SS Maximum Ratings & Electrical Characteristics
| Family | PIC18 PIC XLP 18K |
| Core Architecture | 8-bit PIC enhanced RISC |
| Program Memory (Flash) | 128 KB |
| SRAM | 4 KB |
| EEPROM | 256 B |
| Maximum CPU Speed | 64 MHz |
| Operating Voltage Range | 1.8 V to 3.6 V |
| ADC | 10-bit ADCC with CVD |
| DAC | 5-bit |
| Comparators | 2 |
| PWM Channels | Multiple (CCP/CWG) |
| Communication Interfaces | 2x I2C, 2x SPI, 2x UART |
| Package | 28-pin SSOP |
| Operating Temperature | -40C to +85C (Industrial) |
| XLP Sleep Current | <50 nA typical |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Watchdog | Windowed WDT (WWDT) |
| Memory Scan | CRC/SCAN |
| Zero-Cross Detect | Yes |
PIC18LF27K40-I/SS Pin Configuration
| Pin 1 | RA2/AN2 — Port A bit 2 / Analog input 2 |
| Pin 2 | RA3/AN3 — Port A bit 3 / Analog input 3 |
| Pin 3 | RA4/AN4 — Port A bit 4 / Analog input 4 |
| Pin 4 | RA5/AN5 — Port A bit 5 / Analog input 5 |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RA7 — Port A bit 7 |
| Pin 7 | RA6 — Port A bit 6 |
| Pin 8 | RC0 — Port C bit 0 |
| Pin 9 | RC1 — Port C bit 1 |
| Pin 10 | RC2 — Port C bit 2 |
| Pin 11 | RC3 — Port C bit 3 |
| Pin 12 | RC4 — Port C bit 4 |
| Pin 13 | VDD — Positive supply voltage (1.8V-3.6V) |
| Pin 14 | VSS — Ground reference |
| Pin 15 | RC5 — Port C bit 5 |
| Pin 16 | RC6 — Port C bit 6 |
| Pin 17 | RC7 — Port C bit 7 |
| Pin 18 | RB0 — Port B bit 0 / Interrupt-on-change |
| Pin 19 | RB1 — Port B bit 1 / Interrupt-on-change |
| Pin 20 | RB2 — Port B bit 2 / Interrupt-on-change |
| Pin 21 | RB3 — Port B bit 3 / Interrupt-on-change |
| Pin 22 | RB4 — Port B bit 4 / Interrupt-on-change |
| Pin 23 | RB5 — Port B bit 5 / Interrupt-on-change |
| Pin 24 | RB6/PGC — Port B bit 6 / ICSP clock |
| Pin 25 | RB7/PGD — Port B bit 7 / ICSP data |
| Pin 26 | RE3/MCLR — Reset / Master Clear input |
| Pin 27 | RA0/AN0 — Port A bit 0 / Analog input 0 |
| Pin 28 | RA1/AN1 — Port A bit 1 / Analog input 1 |
Typical Applications
PIC18LF27K40-I/SS is suitable for 6 applications: Battery-Powered IoT Sensor Node, Capacitive Touch User Interface, Home Automation Controller, Remote Control / Wireless Key FOB, Small Motor / Pump Driver, Low-Power Data Logger.
Battery-Powered IoT Sensor Node
The PIC18LF27K40-I/SS is well suited to wireless sensor nodes running on a single 3 V lithium coin cell because its LF voltage range of 1.8 V to 3.6 V matches coin-cell chemistries without a boost converter and its XLP nanWatt technology achieves typical sleep currents below 50 nA. The 10-bit ADCC with Capacitive Voltage Divider automates touch and sensor acquisition without waking the CPU, while the 128 KB Flash supports over-the-air update bootloaders and lightweight network stacks such as LoRaWAN or Zigbee MAC layers. At 64 MHz the device executes sensor-fusion logic in real time while keeping power budget small.
Recommended
Capacitive Touch User Interface
The PIC18LF27K40-I/SS drives capacitive touch keypads, sliders, and proximity widgets because the 10-bit ADCC with built-in CVD support automates charge-transfer measurement on multiple channels in parallel and triggers wake-up interrupts only on valid touches. The Core Independent Peripherals let you scan 16+ electrodes without CPU intervention, slashing firmware complexity and average current. The 4 KB SRAM holds debounce state and gesture logic, while 128 KB Flash hosts the touch library and any UI animations on a connected display.
Recommended
Home Automation Controller
In wall switches, fan controllers, and HVAC sub-controllers the PIC18LF27K40-I/SS acts as the local intelligence because 128 KB Flash easily supports Modbus, BACnet, or proprietary RF protocols and the two UART/SPI/I2C blocks allow simultaneous connectivity to sensors and external radios. The 5-bit DAC, two comparators, and PWM outputs simplify phase-angle or zero-cross control of TRIAC-based AC loads, while WWDT protects against firmware lockups in unattended deployments. The LF voltage range is satisfied by 3.3 V power rails from mains-derived AC-DC modules.
Recommended
Remote Control / Wireless Key FOB
The PIC18LF27K40-I/SS is ideal for handheld key fobs and remote controls because its sub-50 nA sleep current, integrated ADCC, and 1.8 V supply operation let the device run years on a single CR2032 cell. The peripheral set supports direct keypad matrix scanning plus PWM for indicator LEDs and 5-bit DAC for piezo transducer tones. 128 KB Flash is overkill for the application but allows end-of-line customisations, multi-protocol support (RF4CE, BLE-LE Coded PHY), and OTA firmware updates.
Recommended
Small Motor / Pump Driver
The PIC18LF27K40-I/SS can directly orchestrate small DC, stepper, or BLDC motors via its CWG, PWM, and CCP modules because the Complementary Waveform Generator produces hardware-timed switching with programmable dead-band and the ZCD peripheral synchronises PWM output to AC mains zero crossings for TRIAC drivers. The 10-bit ADC reads motor current and back-EMF while the WWDT ensures recovery from fault conditions. Designers can keep firmware in 128 KB Flash including PID and current-loop control code.
Recommended
Low-Power Data Logger
Logger designs for temperature, vibration, or asset tracking rely on the PIC18LF27K40-I/SS because the 4 KB SRAM buffers burst sensor samples while the 256-byte EEPROM and external Flash store history across power cycles. The ADCC's averaging modes reduce noise to enable precise temperature logging without external filtering. XLP sleep currents extend coin-cell life through years of unattended deployment, and 64 MHz compute allows on-the-fly compression or FFT analysis when needed.
Recommended
Recommended Products Summary
Engineering reference data for PIC18LF27K40-I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F27K40-I/SS | PIC18LF26K40-I/SS | PIC18F26K40-I/SS | PIC18LF27K40-I/SO |
|---|---|---|---|---|---|
| Package | 28-SSOP | 28-SSOP | 28-SSOP | 28-SSOP | 28-SOIC (different footprint) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Flash Memory | 128 KB | 128 KB | 64 KB | 64 KB | 128 KB |
| SRAM | 4 KB | 4 KB | 2 KB | 2 KB | 4 KB |
| Operating Voltage | 1.8 V to 3.6 V | 2.0 V to 5.5 V | 1.8 V to 3.6 V | 2.0 V to 5.5 V | 1.8 V to 3.6 V |
| CPU Speed | 64 MHz | 64 MHz | 64 MHz | 64 MHz | 64 MHz |
| EEPROM | 256 B | 256 B | 256 B | 256 B | 256 B |
| ADC | 10-bit ADCC + CVD | 10-bit ADCC + CVD | 10-bit ADCC + CVD | 10-bit ADCC + CVD | 10-bit ADCC + CVD |
Key Differentiators
- Highest memory tier in PIC18 K40 family (vs PIC18LF26K40-I/SS)
- Low-voltage LF operation down to 1.8 V (vs PIC18F27K40-I/SS)
- Wide-SSOP footprint with same peripheral count (vs PIC18LF26K83-I/SS)
Design Notes
The PIC18LF27K40-I/SS operates from 1.8 V to 3.6 V on VDD (pin 13). Place a 100 nF X7R ceramic bypass capacitor within 5 mm of the VDD pin and a 10 uF bulk capacitor on the supply rail. Use an MCP1700 LDO if a clean 3.3 V rail is needed from a higher-voltage source. Estimated: with typical 5 mA active current at 64 MHz and sleep below 50 nA, a CR2032 cell (220 mAh) lasts roughly 6 months of 1% duty cycle.
The 28-pin SSOP package has a 0.65 mm pin pitch requiring careful PCB land pattern design. Route the ICSP clock (PGC, pin 24) and data (PGD, pin 25) traces as short as possible to programming header noise sources. Keep the analog AV inputs (RA0-RA5) away from PWM switching outputs (RC0-RC7) to avoid digital-noise coupling into ADCC measurements. The ADCC reference voltage pin requires its own 100 nF bypass for accurate conversions.
Do not apply supply voltage above 3.6 V to the LF variant - this damages the Flash and EEPROM cells. Configure unused I/O pins as digital outputs driven low to minimize transient current. When migrating from PIC18F27K40 firmware, ensure that voltage-related configuration bits are updated; otherwise brown-out detection may fire prematurely. The MCLR reset pin requires a 10 kohm pull-up to VDD for reliable operation; floating MCLR triggers spurious resets.
The ADCC's CVD measurement is sensitive to high-frequency noise on the touch electrodes. Add a 100 ohm series resistor close to the IO driving each electrode to dampen resonance, and shield long traces by surrounding them with a grounded copper ring. According to Microchip AN1478, the recommended sampling rate for CVD is 50 kHz to balance speed and accuracy. Use the device's internal fixed-voltage reference for ratiometric conversion to maximise noise rejection.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified; choose the PIC18F27K40-E/SS extended temperature variant or PIC18LF27K40-E/SS for industrial-grade 125C support.
