NXP Semiconductors MC68HC908QT2CDW

Overview

MC68HC908QT2CDW from NXP (formerly Freescale) is an 8-bit HCS08-core microcontroller with 2 KB FLASH, 128 B RAM, internal RC oscillator (4 MHz typical), 8-pin SOIC-W package, and integrated ADC, COP watchdog, LVI, and keyboard interrupt module - used in low-cost sensor interface and appliance control applications.

For engineers reviewing the MC68HC908QT2CDW datasheet, MC68HC908QT2CDW pinout, MC68HC908QT2CDW application, or MC68HC908QT2CDW equivalent, key selection considerations include its 8-pin SOIC-W footprint, 4 MHz internal clock accuracy (±2% over temperature), 8-bit ADC with 4-channel input, COP timeout programmability, and support for STOP/WAIT low-power modes in battery-operated systems.

Technical Context

The MC68HC908QT2CDW implements the M68HC08 CPU core with 16-bit address bus, Harvard architecture memory map, and on-chip FLASH memory supporting in-system programming via single-wire background debug mode (BDM). It integrates a 4-channel 8-bit ADC with software-selectable conversion clock source and configurable trigger sources.

Its oscillator subsystem supports internal RC (4 MHz ±2%), external crystal (up to 8 MHz), or external clock input, with automatic failover capability. The SIM module provides reset generation, clock gating, and interrupt vector management for IRQ, KBI, ADC, and COP events.

Key Specifications

Pinout & Package

MC68HC908QT2CDW is housed in an 8-pin SOIC-W (Small Outline Integrated Circuit, Wide-body) package per Freescale package code DW, with 1.27 mm lead pitch and 0.300-inch body width (case #751BD).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC908QT4CDW, the MC68HC908QT2CDW offers identical peripherals and pinout but half the FLASH capacity - suitable for minimal firmware deployments. Against MC9RS08KA2CSCR, it delivers hardware KBI and tighter oscillator tolerance at the expense of slightly higher unit cost and legacy toolchain dependency.

Availability

MC68HC908QT2CDW is available at Aetrix Electronics and suitable for home appliance control, industrial sensor interface, and consumer remote control applications requiring stable component supply across long-lifecycle production programs.

Supply support for MC68HC908QT2CDW 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

NXP Semiconductors is a global semiconductor company formed from the spin-off of Philips' semiconductor division, specializing in secure connectivity solutions for automotive, industrial, and IoT markets.

The MC68HC908QT2CDW belongs to the legacy HCS08 microcontroller family, designed for cost-sensitive, low-pin-count embedded control applications where integration of ADC, KBI, and low-power operation is essential.

FAQ

What is the maximum operating frequency of the MC68HC908QT2CDW?

The MC68HC908QT2CDW supports a maximum bus clock frequency of 8 MHz when using an external crystal or clock source. Its internal RC oscillator operates at 4 MHz ±2% over temperature and voltage, and can be trimmed via the OSCTRIM register to improve accuracy. The CPU executes instructions at the bus clock rate, with most instructions completing in 1–3 cycles.

Does the MC68HC908QT2CDW support in-circuit programming?

Yes, the MC68HC908QT2CDW supports in-circuit programming via its single-wire Background Debug Mode (BDM) interface. This allows full FLASH erase, program, and verification without removing the device from the PCB. A compatible BDM pod (e.g., P&E Micro's USB-ML-12) and Codewarrior or S08 IDE are required for development and field updates.

What are the low-power modes supported by the MC68HC908QT2CDW?

The MC68HC908QT2CDW supports two primary low-power modes: WAIT mode halts the CPU clock while preserving RAM and register contents, drawing ~10 µA; STOP mode disables all clocks except the LVI and COP modules, reducing current to <1 µA. Both modes are entered via specific instruction sequences and exited by reset or enabled interrupts.

Can the MC68HC908QT2CDW drive an external crystal?

Yes, the MC68HC908QT2CDW can drive an external crystal connected between OSC1 and OSC2 pins. It supports fundamental-mode crystals from 100 kHz to 8 MHz. Load capacitance must match the crystal specification (typically 12–22 pF), and external capacitors are required per Freescale's recommended layout in the MC68HC908QY/QT Family Data Sheet, Rev. 6.

Is there a replacement or successor part for the MC68HC908QT2CDW?

NXP does not designate a direct pin- and code-compatible successor to the MC68HC908QT2CDW. The RS08 and S08 families (e.g., MC9RS08KA2) offer modern toolchains and lower power but differ in register mapping, interrupt vectors, and peripheral configuration. Migration requires firmware rework and PCB review. For long-term supply, Aetrix Electronics maintains active inventory and lifecycle coordination for the MC68HC908QT2CDW.