NXP Semiconductors MC68HC908KX2CP

Overview

MC68HC908KX2CP from Freescale Semiconductor is an 8-bit M68HC08-core microcontroller with 2 KB on-chip FLASH, 128 bytes RAM, integrated 8-channel 8-bit ADC, keyboard interrupt module (KBI), and internal clock generator (ICG) supporting DCO-based frequency synthesis. It operates from 4.5 V to 5.5 V across –40°C to +125°C and targets low-cost industrial control and appliance timing applications.

For engineers reviewing the MC68HC908KX2CP datasheet, MC68HC908KX2CP pinout, MC68HC908KX2CP application, or MC68HC908KX2CP equivalent, key selection criteria include its 2 KB FLASH density, IRQ1/PTA0–PTA4 internal pullup resistor values (19–48 kΩ), ICG trimmable DCO operation, KBI-driven wake-up capability, and SOIC-20 package compatibility with legacy HC08 toolchains.

Technical Context

The MC68HC908KX2CP implements the M68HC08 CPU core with 59-instruction set, 16-bit address bus, and Harvard architecture memory map. Its ICG module integrates a digitally controlled oscillator (DCO), modulo-N divider, digital loop filter, and frequency comparator for self-calibrating clock generation without external crystal in basic configurations.

It features a dedicated Keyboard Interrupt Module (KBI) with configurable edge-sensitive inputs on PTA0–PTA4, enabling low-power wake-up from Stop mode via mechanical keypad events. The 8-channel 8-bit ADC supports single-ended conversion with programmable sample time and optional continuous mode, referenced to VREFH or VDD.

Key Specifications

Pinout & Package

MC68HC908KX2CP is housed in a 20-pin SOIC (Small Outline Integrated Circuit) package with 0.300-inch body width and standard JEDEC MS-013AC footprint. Pin assignments follow Freescale's HC08 family layout, including dual-function port pins and dedicated reset/IRQ/oscillator terminals.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with MC68HC908KX8CP, the MC68HC908KX2CP trades FLASH capacity for cost-sensitive designs; versus MC9RS08KA2CP, it retains KBI for mechanical keypad systems but consumes more active power and lacks modern low-power modes.

Availability

MC68HC908KX2CP is available at Aetrix Electronics and suitable for industrial motor control panels, home appliance keypad interfaces, and automotive HVAC blower control requiring stable component supply over extended product lifecycles.

Supply support for MC68HC908KX2CP includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Freescale Semiconductor (now part of NXP Semiconductors) was a leading designer of embedded processors, analog, and connectivity solutions for automotive, industrial, and consumer markets.

The MC68HC908KX2CP belongs to the M68HC08 microcontroller family, engineered for cost-sensitive, real-time control applications demanding reliability, integrated peripherals, and long-term manufacturability in harsh environments.

FAQ

What is the maximum operating frequency of the MC68HC908KX2CP?

The MC68HC908KX2CP supports a maximum bus frequency of 8 MHz when driven by an external crystal or oscillator. Its internal DCO-based ICG can be trimmed to deliver stable frequencies within ±2% accuracy across temperature and voltage, typically enabling reliable 4–6 MHz operation without external timing components. The MC68HC908KX2CP does not support frequencies above 8 MHz due to core and peripheral timing constraints defined in the Rev. 2.1 datasheet.

Does the MC68HC908KX2CP support in-circuit programming?

Yes, the MC68HC908KX2CP supports in-circuit programming via its built-in monitor ROM and standard Freescale HC08 background debug mode (BDM). Programming requires a compatible BDM pod and CodeWarrior IDE, using the IRQ1 and RESET pins for communication. The MC68HC908KX2CP's 2 KB FLASH is organized into 64-byte pages, allowing selective erasure and reprogramming without full chip erase.

Can the MC68HC908KX2CP operate without an external crystal?

Yes, the MC68HC908KX2CP can operate without an external crystal by enabling its internal clock generator (ICG) in DCO mode. The ICG uses a ring oscillator with digital trimming (via TRIM7:TRIM0) to achieve usable clock accuracy for non-timing-critical applications. The MC68HC908KX2CP's datasheet specifies DCO calibration procedures and typical frequency stability across voltage and temperature ranges.

What is the purpose of the VREFH pin on the MC68HC908KX2CP?

The VREFH pin on the MC68HC908KX2CP serves as the positive voltage reference input for the 8-bit ADC. It can be connected directly to VDD or to an external precision reference (≤ VDD) to improve ADC measurement accuracy and noise immunity. When VREFH is tied to VDD, the ADC full-scale range equals the supply voltage; decoupling VREFH with a 100 nF capacitor is recommended to minimize switching noise coupling into analog measurements. This configuration is used in all MC68HC908KX2CP ADC applications.

How does the Keyboard Interrupt Module (KBI) function on the MC68HC908KX2CP?

The Keyboard Interrupt Module (KBI) on the MC68HC908KX2CP monitors PTA0–PTA4 for edge-triggered transitions and generates an interrupt request (KBIIF) upon detection. It supports both rising and falling edge selection per pin and remains active in Stop mode, enabling wake-up from ultra-low-power states. The MC68HC908KX2CP's KBI eliminates the need for external interrupt logic or polling loops, reducing firmware complexity and average system current in keypad-based products.