PIC18F27K40-E/SS Komplettleitfaden: 8-Bit Microchip MCU Spezifikationen, Pinout, Alternativen & Beschaffung (2026)

Quick Answers: What is the PIC18F27K40-E/SS and why should you select it?

The Microchip Technology PIC18F27K40-E/SS is an 8-bit PIC18 RISC microcontroller in a 28-pin SSOP package, integrating 128 KB of Flash program memory (organized as 64K x 16), 4 KB of SRAM, and 256 bytes of EEPROM. It executes at up to 64 MHz (16 MIPS) from a 3.0 V to 5.5 V supply and is qualified to the Extended temperature grade of -40 °C to +125 °C. Core Independent Peripherals (CIPs) - including the Complementary Waveform Generator (CWG), Windowed Watchdog Timer (WWDT), CRC/Scan, and Hardware Limit Timer (HLT) - plus a 10-bit ADC with up to 24 channels, a 5-bit DAC, an Enhanced USART, and an MSSP (SPI / I²C) form a self-sufficient compute subsystem. The device is active in lifecycle, currently in stock at 99,999 units on the PIC18F27K40-E/SS product page, and priced from USD 2.50 at qty 1 down to USD 1.65 at qty 1,000 (as of 2026-10-06). Engineers select it when they need a high-memory 8-bit MCU that combines XLP sub-50 nA sleep behavior with rich CIP integration in a compact 28-SSOP footprint.

Technical Guide: How do you design in and use the PIC18F27K40-E/SS?

The PIC18F27K40-E/SS targets designs that sit between simple 8-bit tasks and 32-bit overkill. Three design pillars make it a productive choice: deterministic 16 MIPS throughput from the enhanced Harvard bus, a generous 128 KB Flash for full protocol stacks, and an unusually rich CIP block that frees the CPU from real-time housekeeping. This section walks through the design decisions that drive a successful board bring-up.

Power, clock, and reset

Connect VDD (pin 18) to a regulated 3.3 V or 5 V rail within the 3.0 V to 5.5 V window, and tie both VSS pins (8 and 19) to ground with a low-impedance return path. The internal 64 MHz oscillator eliminates external crystals in most designs, but pins RA6 (OSC2, pin 7) and RA7 (OSC1, pin 9) can drive an external source if your EMC plan requires it. The Extended -E grade guarantees operation from -40 °C to +125 °C, so no derating is required for under-hood appliance or industrial cabinet layouts. Programming voltage is generated internally by the high-voltage In-Circuit Serial Programming block on RB6/RB7, so no external HV pin is required.

Peripheral Pin Select and I/O planning

The K40 family uses enhanced Peripheral Pin Select (PPS), which lets you remap EUSART, MSSP, and CCP outputs onto most digital I/O pins. Plan I/O around the analog channels you actually need: AN0-AN4 sit on PORTA, AN8-AN11 on PORTB, and AN12-AN19 on PORTC, plus AN5 on RE3 (pin 28) - that is the 24-channel ADC ceiling for this 28-pin package. When migrating from older PIC18 devices such as the PIC18F25K22, validate interrupt vector mapping and PPS reassignments rather than carrying code over directly; the K40 enhanced PPS differs from earlier baselines.

Analog front end

The 10-bit ADC runs up to 24 channels with internal channel scanning, which suits 4-20 mA loop sampling, thermistor bridges, and ratiometric sensor reads without external multiplexing. The 5-bit DAC and the on-chip comparators (paired with the CWG) form a complete threshold-detect / waveform-generate chain without external op-amps, useful for LED dimming loops and over-current protection. For higher analog accuracy, the K40 can be clocked down to give the ADC more sample windows - a useful trade-off at low duty cycles.

Core Independent Peripherals in practice

The CIP block is where the K40 earns its BOM savings. The Complementary Waveform Generator (CWG) produces complementary PWM with dead-band control for half-bridge FET drivers. The Windowed Watchdog Timer (WWDT) wakes the part from sleep on a fault window without waking the application core. CRC/Scan computes memory checksums in hardware, validating firmware integrity at boot. The Hardware Limit Timer (HLT) offloads hardware button debouncing and time-of-flight timing. Together, these let a 16 MIPS core spend most of its cycles on application logic rather than interrupt service routines.

Direct LED drive and I/O current

The PIC18F27K40 I/O pins can source or sink up to 50 mA per pin in high-current drive mode, which is enough to eliminate external driver transistors for simple LED indicators and small RGB matrices. For multi-channel LED strings, pair the CWG outputs with small MOSFETs and use the 5-bit DAC and a comparator as a closed-loop current limiter. Direct 5 V LED rail operation simplifies the power tree because the 3.0 V to 5.5 V VDD range matches common LED forward voltages.

Programming and debug

In-circuit programming uses RB6 (ICDCLK, pin 16) and RB7 (ICDDAT, pin 17). Production programming voltage is internally generated, so no external HV pin is needed. For low-power designs, use the XLP sleep modes and exit via WWDT or an Interrupt-on-Change (IOC) event on any of the IOC-capable pins. A typical current budget is below 50 nA in deep sleep with WWDT running, suiting coin-cell sensor nodes that must last 5+ years on a single primary cell.

Communication interfaces

The Enhanced USART (EUSART) handles RS-232, RS-485 (with an external transceiver), or LIN through a single UART. The MSSP block supports both SPI master/slave and I²C master/slave - useful for sensor hubs, OLED displays, and external EEPROM. For full CAN, add an external MCP2515 or MCP25625 - the K40 does not integrate a CAN module, but the EUSART can drive LIN directly with the right firmware.

Engineer takeaway: budget I/O first, then assign peripherals through PPS rather than the other way around. This keeps the firmware portable across the K40 and K42 families and protects you against last-minute pin swaps.

Alternatives & Comparison: Which parts can drop into the PIC18F27K40-E/SS socket?

Six drop-in candidates are in scope for a 28-pin SSOP board. The right choice depends on whether you need a true silicon-compatible drop-in, a footprint-compatible upgrade, or a cross-architecture port. The table below compares the verified data points available in the XAIPART database for each candidate.

The PIC18F27K40-I/SS is the cleanest drop-in: identical silicon, identical 28-SSOP footprint, only the temperature grade changes from -40 °C to +125 °C down to -40 °C to +85 °C. The PIC18F27K42-E/SS on the PIC18F27K42-E/SS product page is the recommended upgrade path when you need more PWM channels or enhanced CIPs in the same 28-SSOP board. The PIC18F25Q43-I/STX on the PIC18F25Q43-I/STX product page is the newer Q43 family and matches the 28-SSOP footprint with enhanced peripherals. The PIC18F24K22-I/SSVAO on the PIC18F24K22-I/SSVAO product page is the cost-down option when 16 KB Flash is acceptable. Cross-architecture: the ATTINY1626-XU on the ATTINY1626-XU product page fits the same 28-SSOP footprint but is AVR-core, so it requires firmware porting. Avoid the PIC18F27K40-E/SP for SSOP boards - it is SPDIP through-hole and not pin-compatible.

Engineer takeaway: keep two alternates qualified - the same-die industrial grade and the next-gen K42. That covers supply shocks and future-proofing without changing the PCB.

Industry Insight: What is the PIC18F27K40-E/SS's market position and supply picture?

The PIC18F27K40-E/SS is in active production lifecycle. Distributor stock is reported at 99,999 units with a minimum order quantity of 1, so single-piece prototyping is supported. Pricing as of 2026-10-06 follows a clear volume curve: USD 2.50 at qty 1, USD 2.25 at qty 10, USD 2.00 at qty 100, USD 1.80 at qty 500, and USD 1.65 at qty 1,000. That is a 34 percent unit-cost reduction between qty 1 and qty 1,000, which is the kind of curve that lets volume builders hit aggressive BoM targets without sourcing negotiations. The wide 3.0 V to 5.5 V supply, -40 °C to +125 °C Extended grade, and RoHS-compliant lead-free 28-SSOP package keep it aligned with current industrial, appliance, and consumer requirements. The K40 family is mature in Microchip's catalog - the next-gen K42 (covered in our PIC18F25Q43-I/STX Complete Guide) carries the roadmap for designs that need more PWM. AEC-Q100 qualification is not claimed for the standard K40; for full automotive safety, use a K40 variant explicitly qualified for that grade. For cross-reference and current stock data, browse the XAIPART catalog.

Engineer takeaway: the K40 sits in a healthy supply window, but the family is being supplemented (not replaced) by K42 and Q43. Plan a PCB that accepts both to de-risk your 2027 sourcing.

Trends & Outlook: What should buyers watch next?

Three trends matter for K40 buyers through 2026 and 2027. First, the migration wave from K22 and earlier to K40 and K42 - Microchip's own roadmap is steering new 8-bit designs toward the newer CIP-rich cores, and the PIC18F24K22-I/SSVAO Complete Guide covers the older K22 family in detail. Second, low-power IoT demand is pulling the XLP sleep story (sub-50 nA) into mainstream sensor nodes, which keeps the K40's 128 KB Flash plus 4 KB RAM combination attractive for protocol stacks that used to require a 32-bit part. Third, the Q43 family - covered in the PIC18F25Q43-I/STX Complete Guide - is setting the new performance baseline for 8-bit at 64 MHz.

Anchor your next design on verified specs: 128 KB Flash, 64 MHz core, 24 ADC channels, 3.0 V to 5.5 V VDD, and sub-50 nA sleep. Watch the lifecycle column on the PIC18F27K40-E/SS product page for any active-to-not-for-new-design transitions, and re-validate the qty 1,000 price band every quarter - 8-bit MCU pricing has been more stable than 32-bit, but allocations still happen. For more context on 8-bit PIC migration, the PIC16LF18313-I/SN Complete Guide and the PIC18F1320-I/ML guide are useful companions. If you are crossing over from 16-bit territory, the MSP430G2210IDR Complete Guide offers a useful side-by-side, and the XAIPART Blog index tracks the rest of the 8-bit and 16-bit coverage.

Engineer takeaway: lock in a footprint that accepts K40 today and K42 / Q43 tomorrow. That single PCB decision buys you a decade of 8-bit sourcing flexibility without another respin.