NXP Semiconductors MCHC908QT1CDWE

Overview

MCHC908QT1CDWE from Freescale Semiconductor is an 8-bit HCS08-core microcontroller in the MC68HC908QT family, featuring 1 KB FLASH, 64 bytes RAM, internal RC oscillator (4 MHz typical), 8-pin SOIC package, and integrated ADC, COP watchdog, LVI, and keyboard interrupt module - used in cost-sensitive embedded control applications such as appliance timers and sensor interface modules.

For engineers reviewing the MCHC908QT1CDWE datasheet, MCHC908QT1CDWE pinout, MCHC908QT1CDWE application, or MCHC908QT1CDWE equivalent, key selection criteria include its 8-pin SOIC footprint, 4 MHz internal clock accuracy (±5% over temperature), 8-bit ADC with 4-channel input, low-voltage inhibit threshold at 2.7 V, and compatibility with HC08 development tools including P&E Multilink and CodeWarrior IDE.

Technical Context

The MCHC908QT1CDWE implements the HCS08 CPU core with 16-bit address bus, supports WAIT/STOP low-power modes, and uses a trimmable internal RC oscillator as primary clock source. It integrates a 4-channel 8-bit ADC with programmable conversion time (16–64 µs), configurable keyboard interrupt (KBI) on Port A pins, and a Computer Operating Properly (COP) watchdog with selectable timeout (0.5–16 ms).

Its memory map includes 1 KB of on-chip FLASH (with block protection), 64 bytes of RAM, and dedicated I/O registers mapped to $00–$3F. The device lacks external bus interface and uses only internal clocking - no crystal oscillator circuitry is present, distinguishing it from QT4/QY4 variants with XTAL support.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (SO-8), 150 mil body width, standard JEDEC MS-012AC outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908QT4CDWE and MC908QY1CDWE, the MCHC908QT1CDWE delivers optimal balance of minimal footprint, integrated wake-up logic, and lowest BOM cost for sub-1 KB control firmware - making it ideal for space-constrained, battery-aware, or high-volume cost-sensitive designs.

Availability

MCHC908QT1CDWE is available at Aetrix Electronics and suitable for home appliance timer control, industrial sensor interface, and smart power outlet applications requiring stable component supply and long-term industrial temperature support (–40°C to +85°C).

Supply support for MCHC908QT1CDWE 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) is a pioneer in 8-bit microcontroller architecture, known for robust automotive and industrial-grade silicon with strong toolchain support.

The MC68HC908QT family was designed for ultra-low-cost, low-pin-count embedded control - emphasizing minimal external components, integrated peripherals, and ease of certification in white-goods and industrial equipment.

FAQ

What is the maximum operating frequency of the MCHC908QT1CDWE?

The MCHC908QT1CDWE operates with a trimmed internal RC oscillator rated at 4 MHz typical, with ±5% variation across –40°C to +85°C. It does not support external crystal oscillators or higher-frequency clock sources - the bus clock is derived directly from this internal oscillator, limiting maximum instruction throughput to approximately 1 MIPS.

Does the MCHC908QT1CDWE support in-circuit debugging?

Yes, the MCHC908QT1CDWE supports single-wire background debug mode using the RESET pin. This allows full read/write access to memory and registers, breakpoint setting, and firmware download without requiring additional debug pins - enabling debugging on the final PCB layout with no debug header footprint.

Can the MCHC908QT1CDWE drive LEDs directly from its I/O pins?

Yes, MCHC908QT1CDWE I/O pins (PTA0–PTA3) can sink up to 15 mA and source up to 5 mA per pin. This allows direct LED driving in common-cathode configuration (e.g., PTAx → LED → VDD), provided total port current remains below 50 mA - suitable for status indicators in low-power appliances.

What is the ADC reference voltage for the MCHC908QT1CDWE?

The MCHC908QT1CDWE ADC uses VDD as its reference voltage by default. No separate AVDD or external reference pin is provided. Therefore, ADC resolution and accuracy scale directly with supply voltage stability - a 5% VDD variation causes proportional full-scale error in converted values.

Is the MCHC908QT1CDWE pin-compatible with other MC68HC908QT family members?

No, the MCHC908QT1CDWE is not pin-compatible with MC908QT4CDWE or MC908QY1CDWE. While all three use 8-pin SOIC packages, the QT1 variant assigns PTA4 as BUSCLKX4 output, whereas QT4 uses that pin for TCLK input and QY1 reassigns it as general-purpose I/O - requiring distinct PCB layouts for each part.