PIC18F45K20-I/ML - 8-bit 64MHz MCU 32KB Flash 44-QFN | Microchip
MPN: PIC18F45K20-I/ML ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.1 | $31.00 |
| 100 | $2.78 | $278.00 |
| 500 | $2.45 | $1,225.00 |
| 1,000 | $2.2 | $2,200.00 |
| 3,000 | $1.95 | $5,850.00 |
PIC18F45K20-I/ML Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program and data memory, peripherals, and I/O. The PIC18 family uses an enhanced 8-bit RISC Harvard architecture with hardware multiplier and 16-bit wide instructions, sitting between 16-bit PIC24 parts and 8-bit PIC16/12 parts in the Microchip portfolio. XLP (nanoWatt eXtreme Low Power) is Microchip's branding for ultra-low sleep current (<100 nA typical) suitable for battery-powered edge devices. The K-series in particular targets migration from legacy PIC18F4xK20 designs by offering more memory and analog channels.
Key specifications include 1.8-3.6V core operation with 4.2-5.5V extended Vdd range (with internal 1.2V FVR reference), 32 KB self-programmable Flash, 1.5 KB SRAM, 256 B EEPROM, 36 digital I/O, and four timer modules. The 10-bit ADC supports 14 channels with auto-acquisition and is operable during Sleep for low-power sensing. Two analog comparators with independent input multiplexing and programmable reference enable mixed-voltage designs without external op-amps.
The device uses a high-performance 8-bit RISC core with a hardware multiply and a 16-level hardware stack. Internal PLL multiplies the 16 MHz HFINTOSC up to 64 MHz, eliminating external crystals in cost-sensitive designs. The 1.2V fixed voltage reference (FVR) channel provides a stable on-chip reference for the ADC and comparators, while charge time measurement unit (CTMU) support enables capacitive touch and time-of-flight measurement.
Typical applications include low-power remote sensor nodes, HVAC and thermostat controllers, consumer white goods, battery chargers, USB-to-UART bridges (combined with external PHY), home automation gateways, and small industrial control boards where sleep current, on-chip analog, and 5V tolerance are critical. The 25 mA sink/source also supports direct LED driving without external transistors.
When designing with this MCU, observe Vdd/Vss decoupling guidance (100 nF + bulk), and review errata for any silicon revisions in the JEDEC-qualified QFN-44 footprint. For new designs, consider PIC18F45K22 for additional memory and peripherals, or PIC18F46K20 for 64 KB Flash in the same package.
This page synthesizes distributor pricing, parametric drop-in alternatives, and practical design notes that go beyond what the manufacturer datasheet alone provides.
Drop-in alternatives for PIC18F45K20-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 PIC18F45K20-I/ML (same form factor and footprint) — differing in Core Architecture, ADC, Package, MSL Level, RAM.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18F45K22-I/ML
✅ Drop-In✓ In Stock
$2.65 / Unit
View Datasheet →PIC18F46K20-I/ML
✅ Drop-In✓ In Stock
$3.52 / Unit
View Datasheet →PIC18F44K20-I/ML
✅ Drop-In📋 Reference alternative (not in catalog)
PIC18F43K20-I/ML
✅ Drop-In✓ In Stock
$2.46 / Unit
View Datasheet →PIC18F45J11-I/ML
✅ Drop-In✓ In Stock
$3.25 / Unit
View Datasheet →PIC18F45K20-I/ML Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (Harvard) |
| Core Size | 8-bit |
| Program Memory | 32 KB Flash (16K x 16 words) |
| RAM | 1536 bytes |
| EEPROM | 256 bytes |
| Maximum CPU Speed | 64 MHz (16 MIPS) |
| Operating Voltage (Vdd) | 1.8 V to 3.6 V (4.2 V to 5.5 V extended) |
| I/O Pins | 36 |
| ADC | 10-bit, 14 channels |
| Analog Comparators | 2 (rail-to-rail) |
| Timers | 4 (Timer0/1/2/3) |
| CCP Modules | 2 (Capture/Compare/PWM) |
| Serial Interfaces | EUSART, MSSP (SPI / I2C) |
| Internal Oscillator | 16 MHz HFINTOSC with PLL to 64 MHz |
| Fixed Voltage Reference | 1.2 V on-chip FVR |
| I/O Sink/Source | 25 mA / 25 mA |
| Package | 44-pin QFN (8x8 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial) |
| RoHS Status | Compliant |
| MSL Level | 3 (168 hours) |
PIC18F45K20-I/ML Pin Configuration
| Pin 1 | AVDD — Analog supply voltage |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input 1 |
| Pin 4 | RA2/AN2/VREF- — PORTA bit 2 / Analog input 2 / ADC VREF- |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input 3 / ADC VREF+ |
| Pin 6 | RA4 — PORTA bit 4 |
| Pin 7 | RA5/AN4 — PORTA bit 5 / Analog input 4 |
| Pin 8 | AVSS — Analog ground |
| Pin 9 | OSC1/CLKI/RA7 — Crystal input / External clock / PORTA bit 7 |
| Pin 10 | OSC2/CLKO/RA6 — Crystal output / Clock output / PORTA bit 6 |
| Pin 11 | VDD — Digital supply voltage |
| Pin 12 | VSS — Digital ground |
| Pin 13 | RB0/INT0/FLT0 — PORTB bit 0 / External interrupt 0 / PWM fault |
| Pin 14 | RB1/INT1 — PORTB bit 1 / External interrupt 1 |
| Pin 15 | RB2/INT2 — PORTB bit 2 / External interrupt 2 |
| Pin 16 | RB3/CCP2 — PORTB bit 3 / Capture/Compare/PWM 2 |
| Pin 17 | RB4 — PORTB bit 4 |
| Pin 18 | RB5/CCP1 — PORTB bit 5 / Capture/Compare/PWM 1 |
| Pin 19 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 20 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 21 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 22 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 |
| Pin 23 | RC2/CCP1 — PORTC bit 2 / CCP1 |
| Pin 24 | RC3/SCK/SCL — PORTC bit 3 / MSSP SPI clock / I2C clock |
| Pin 25 | RC4/SDI/SDA — PORTC bit 4 / MSSP SPI data in / I2C data |
| Pin 26 | RC5/SDO — PORTC bit 5 / MSSP SPI data out |
| Pin 27 | RC6/TX/CK — PORTC bit 6 / EUSART TX / EUSART clock |
| Pin 28 | RC7/RX/DT — PORTC bit 7 / EUSART RX / EUSART data |
| Pin 29 | RE0/RD/AN5 — PORTE bit 0 / Parallel slave read / Analog input 5 |
| Pin 30 | RE1/WR/AN6 — PORTE bit 1 / Parallel slave write / Analog input 6 |
| Pin 31 | RE2/CS/AN7 — PORTE bit 2 / Parallel slave chip select / Analog input 7 |
| Pin 32 | VDD — Digital supply voltage |
| Pin 33 | VSS — Digital ground |
| Pin 34 | RF0/AN8 — PORTF bit 0 / Analog input 8 |
| Pin 35 | RF1/AN9/C2OUT — PORTF bit 1 / Analog input 9 / Comparator 2 output |
| Pin 36 | RF2/AN10/C1OUT — PORTF bit 2 / Analog input 10 / Comparator 1 output |
| Pin 37 | RF3/AN11 — PORTF bit 3 / Analog input 11 |
| Pin 38 | RF4/AN12 — PORTF bit 4 / Analog input 12 |
| Pin 39 | RF5/AN13 — PORTF bit 5 / Analog input 13 |
| Pin 40 | RF6 — PORTF bit 6 |
| Pin 41 | RF7 — PORTF bit 7 |
| Pin 42 | VDD — Digital supply voltage |
| Pin 43 | VSS — Digital ground |
| Pin 44 | MCLR/VPP/RE3 — Master clear reset / Programming voltage / PORTE bit 3 |
Typical Applications
PIC18F45K20-I/ML is suitable for 7 applications: Battery-Powered Remote Sensor Nodes, HVAC and Thermostat Controllers, USB-to-UART Bridge Devices, Consumer White Goods Control Boards, Home Automation Gateways, LED Lighting and Display Controllers, Small Industrial Control and Monitoring.
Battery-Powered Remote Sensor Nodes
The PIC18F45K20-I/ML fits battery-powered remote sensor nodes because its nanoWatt XLP technology delivers sub-100 nA sleep current while retaining 32 KB Flash for sensor fusion and protocol stacks. The 64 MHz core supports on-sensor FFT and oversampling, while the 1.2V FVR ensures ADC accuracy across battery discharge. The 14-channel 10-bit ADC handles multi-sensor analog inputs without external multiplexer. In typical 3.3V coin-cell deployments, sleep current dominates total energy, and the K20 architecture maintains RAM retention at <50 nA. Pair with a sub-GHz radio module over SPI for complete node implementation.
Recommended
HVAC and Thermostat Controllers
The PIC18F45K20-I/ML suits HVAC and thermostat controllers because its 36 I/O with 25 mA sink/source drives triac interfaces, relay coils, and seven-segment displays directly without external transistors. The two rail-to-rail analog comparators handle thermistor and humidity sensor signal conditioning, while the 10-bit ADC with 14 channels monitors multiple temperature zones. The industrial temperature grade (-40C to +85C) supports attic and rooftop installations. With internal 64 MHz PLL, no external crystal is required, reducing BOM cost for consumer-priced thermostats.
Recommended
USB-to-UART Bridge Devices
The PIC18F45K20-I/ML works as a USB-to-UART bridge controller when paired with an external USB PHY, because its EUSART module provides hardware UART flow control and its MSSP supports SPI to external devices. The 32 KB Flash fits CDC class drivers and protocol translation firmware, while the 64 MHz core handles full-speed USB packet handling when using a software USB stack. For designs migrating from legacy PIC18F4550 USB parts, the K20 offers similar peripherals with nanoWatt XLP for sleep when USB is idle.
Recommended
Consumer White Goods Control Boards
The PIC18F45K20-I/ML fits washing machine, dishwasher, and refrigerator control boards because its 5V-tolerant extended Vdd range interfaces directly with mains-side signal conditioning. The 36 high-current I/O (25 mA/25 mA) drives LED indicators, buzzer circuits, and relay coils. Industrial temperature grade survives compressor-adjacent thermal stress. The on-chip EUSART and MSSP communicate with motor inverter boards and sensor front-ends, while the 14-channel ADC monitors temperature, pressure, and water-level sensors. The K20's proven long-term availability supports consumer product lifecycles.
Recommended
Home Automation Gateways
The PIC18F45K20-I/ML serves in home automation gateways because its 32 KB Flash stores Zigbee or Z-Wave stack portions while 1536 bytes RAM handles packet buffers and routing tables. The EUSART interfaces with the radio modem over UART, while MSSP provides SPI access to non-volatile memory for routing table persistence. The 64 MHz CPU throughput handles mesh routing without external RTOS. Power-down sleep modes extend battery life in wireless push-button or sensor accessories connected to the gateway.
Recommended
LED Lighting and Display Controllers
The PIC18F45K20-I/ML works as an LED controller because two CCP modules generate hardware PWM for RGB channels and brightness control, while 25 mA source capability drives LED strings directly without MOSFETs in low-power fixtures. The 10-bit ADC reads ambient sensors for daylight harvesting and color-temperature feedback. The industrial temperature grade suits outdoor luminaire environments. Internal 64 MHz clock eliminates external crystal cost in price-sensitive decorative lighting, while the QFN package enables compact driver board designs.
Recommended
Small Industrial Control and Monitoring
The PIC18F45K20-I/ML suits small industrial PLC and sensor interface modules because its industrial temperature grade and 5V tolerance survive plant-floor electrical environments. The EUSART supports RS-485 with external transceiver, while MSSP runs SPI sensors and I/O expanders. The 14-channel ADC reads 4-20 mA loops via external shunt resistors and monitors supply voltage. Programmable comparators implement window-detect alarms for limit-switch inputs. The exposed thermal pad supports continuous operation at full peripheral load.
Recommended
Recommended Products Summary
Engineering reference data for PIC18F45K20-I/ML — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18F45K22-I/ML | PIC18F46K20-I/ML | PIC18F44K20-I/ML | PIC18F43K20-I/ML | PIC18F45J11-I/ML |
|---|---|---|---|---|---|---|
| Brand | 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 |
| Program Memory | 32 KB Flash | 32 KB Flash | 64 KB Flash | 16 KB Flash | 8 KB Flash | 32 KB Flash |
| RAM | 1536 bytes | 1536 bytes | 1536 bytes | 768 bytes | 512 bytes | 1536 bytes |
| Maximum CPU Speed | 64 MHz / 16 MIPS | 64 MHz / 16 MIPS | 64 MHz / 16 MIPS | 64 MHz / 16 MIPS | 64 MHz / 16 MIPS | 48 MHz / 12 MIPS |
| Operating Voltage | 1.8-3.6V (4.2-5.5V extended) | 1.8-3.6V (5.5V extended) | 1.8-3.6V (4.2-5.5V extended) | 1.8-3.6V (4.2-5.5V extended) | 1.8-3.6V (4.2-5.5V extended) | 2.0-3.6V (3.3V only) |
| I/O Pins | 36 | 36 | 36 | 36 | 25 | 34 |
| ADC Channels | 14 x 10-bit | 19 x 10-bit | 14 x 10-bit | 14 x 10-bit | 11 x 10-bit | 13 x 10-bit |
| 5V Tolerant | Yes (extended Vdd) | Yes | Yes | Yes | Yes | No (3.3V only) |
Key Differentiators
- Highest ADC channel count in K20 family at industrial temp grade (vs PIC18F43K20-I/ML)
- 5V tolerance for legacy 5V system migration (vs PIC18F45J11-I/ML)
- Balanced Flash and RAM for moderate firmware size (vs PIC18F46K20-I/ML)
- Established long-term availability for consumer product lifecycles (vs PIC18F45K22-I/ML)
Design Notes
Place a 100 nF decoupling capacitor as close as possible to every Vdd/Vss pin pair (pins 11/12, 32/33, 42/43) and an additional 10 uF bulk capacitor on the main supply rail. For AVDD (pin 1) and AVSS (pin 8), use a separate 100 nF ceramic plus a ferrite bead from digital Vdd to reduce ADC noise. The exposed thermal pad must be soldered to a continuous ground plane for both thermal dissipation and electrical reference. Estimated: at full 64 MHz operation with all peripherals active, ICC is approximately 10 mA; derate accordingly for battery budgets.
Route the analog inputs (PORTA, PORTF) away from switching signals such as PWM outputs on CCP1/CCP2 and oscillator pins. Use a guarded ground plane with separate analog and digital ground regions joined only at the MCU AVSS pin. Keep ADC traces short and matched in length where possible. The MCLR pin (44) requires a 10 kohm pull-up to Vdd; do not leave it floating or the MCU may randomly enter programming mode. Add a 100 nF cap from MCLR to Vdd for brown-out noise immunity.
Do not assume default oscillator configuration; the K20 powers up with internal 16 MHz HFINTOSC but PLL must be enabled in OSCCON for 64 MHz operation. Avoid the 5V-tolerant analog input misconception: while Vdd can extend to 5.5V, analog input voltages must remain within the specified AVSS-AVDD range. When migrating PIC18F4550 firmware, note the K20 has no native USB peripheral - external PHY or migrate to PIC18F45K50 family for USB. Always check current silicon errata from Microchip before locking firmware; revisions affect ADC and PWM behavior.
Although the K20 is a CMOS microcontroller with modest power dissipation, the 44-QFN exposed pad provides critical thermal relief. Estimated: at 64 MHz full-activity with all peripherals on, the device dissipates approximately 50 mA x 3.3V = 165 mW. With proper ground plane soldering, junction-to-ambient thermal resistance is approximately 30 C/W, resulting in a 5C temperature rise at full load. For QFN-44, follow IPC-7351 land pattern with 0.5 mm pitch pads and ensure the center pad has at least 50% solder fillet coverage for reliable thermal performance.
Compliance Information
RoHS and REACH compliant per Microchip product page and Heisener distributor listing. Halogen-free per Microchip environmental compliance documentation. Not AEC-Q100 qualified - this is a commercial/industrial-grade MCU; automotive designs should consider PIC18F46K22-I/ML or PIC18F25K22-I/SO variants.
