NXP Semiconductors MC68HC908KX8CDW

Overview

MC68HC908KX8CDW from Freescale Semiconductor is an 8-bit M68HC08 core microcontroller with 8 KB on-chip FLASH, 512 B RAM, integrated 8-channel 8-bit ADC, and programmable internal clock generator (ICG) supporting DCO-based frequency synthesis. It features 16 I/O pins (Port A and Port B), external interrupt (IRQ1), keyboard interrupt (KBI), COP watchdog, and LVI reset protection - designed for cost-sensitive industrial control and sensor interface applications operating at 4.5–5.5 V.

For engineers reviewing the MC68HC908KX8CDW datasheet, MC68HC908KX8CDW pinout, MC68HC908KX8CDW application, or MC68HC908KX8CDW equivalent, this page delivers verified electrical specs (e.g., 24–48 kΩ internal pullups on PTA0–PTA4), thermal rating (–40°C to +125°C), FLASH endurance (10k erase/write cycles), ICG trim capability, and SOIC-28 package compatibility - all critical for automotive-grade embedded firmware development and long-lifecycle hardware design.

Technical Context

The MC68HC908KX8CDW implements a fully static M68HC08 CPU core with 55-instruction set, supporting WAIT/STOP low-power modes and monitor ROM for in-circuit debugging. Its ICG module integrates a digitally controlled oscillator (DCO), modulo-N divider, digital loop filter, and frequency comparator to generate stable system clocks without external crystals - enabling flexible clock tuning via ICG Trim Register (TRIM7:TRIM0).

ADC operation supports single-ended conversion with programmable input clock division, 10 µs typical conversion time, and reference voltage sourced from VREFH or internal bandgap. The KBI module provides debounced scan of up to 5 keys via PTA4–PTA0, while IRQ1 supports edge-triggered external interrupt with dedicated 19–43 kΩ pullup resistor - both validated across full industrial temperature range.

Key Specifications

Pinout & Package

MC68HC908KX8CDW is housed in a 28-pin SOIC (Small Outline Integrated Circuit) package with 16 general-purpose I/O lines distributed across Port A (PTA4–PTA0) and Port B (PTB7–PTB0), plus dedicated functional pins including IRQ1, OSC1/OSC2, VDD/VSS, VREFH, and RST.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC908KX8CDW, MC9RS08KA8CDT trades integrated analog capability for modern core efficiency, while STM8S003F3P6 offers enhanced ADC and power performance at the cost of complete hardware and software requalification.

Availability

MC68HC908KX8CDW is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body control modules, and appliance control panels requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MC68HC908KX8CDW 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 and analog/mixed-signal ICs, known for automotive, industrial, and networking solutions.

The MC68HC908KX8CDW belongs to the M68HC08 microcontroller family, engineered for cost-effective, low-power 8-bit control in harsh environments - emphasizing integrated peripherals, flash reliability, and wide-temperature operation.

FAQ

What is the maximum operating frequency of the MC68HC908KX8CDW?

The MC68HC908KX8CDW supports a maximum bus frequency of 8 MHz when using the internal ICG with DCO and appropriate trim settings. External crystal operation is rated up to 8 MHz per datasheet Section 17.6. This frequency governs instruction execution speed, ADC sampling rate, and peripheral timing - all validated across –40°C to +125°C.

Does the MC68HC908KX8CDW include a hardware watchdog timer?

Yes, the MC68HC908KX8CDW includes a Computer Operating Properly (COP) watchdog module with configurable timeout intervals ranging from 0.5 ms to 1.0 s. It uses an independent clock source and triggers a hardware reset if not serviced within the selected window - a critical feature for fail-safe operation in the MC68HC908KX8CDW.

Can the MC68HC908KX8CDW operate without an external crystal?

Yes, the MC68HC908KX8CDW can operate without an external crystal by using its integrated Internal Clock Generator (ICG) with Digitally Controlled Oscillator (DCO). The DCO frequency is software-trimmable via the ICG Trim Register, enabling crystal-free designs while maintaining sufficient accuracy for most industrial timing requirements in the MC68HC908KX8CDW.

What is the FLASH endurance specification for the MC68HC908KX8CDW?

The MC68HC908KX8CDW specifies 10,000 erase/write cycles for its 8 KB on-chip FLASH memory, as documented in Section 2.5 and Table 17.11 of the datasheet. This endurance rating applies under standard operating conditions (VDD = 5.0 V, TA = 25°C) and supports field firmware updates and parameter storage in the MC68HC908KX8CDW over multi-year deployments.

How many analog input channels does the MC68HC908KX8CDW support?

The MC68HC908KX8CDW integrates an 8-channel 8-bit successive approximation register (SAR) ADC, with inputs mapped to PTB0–PTB7 (AD0–AD7). All channels support single-ended configuration referenced to VREFH or internal bandgap, and conversion time is typically 10 µs - confirmed in Section 3.3.3 and Table 17.7 of the MC68HC908KX8CDW datasheet.