NXP Semiconductors MC908QT1AMDWE

Overview

MC908QT1AMDWE from Freescale Semiconductor is an 8-bit HCS08-core microcontroller with 4 KB FLASH, 192 B RAM, and integrated ADC10, AWU, COP watchdog, and LVI protection - designed for cost-sensitive industrial control and appliance timing applications requiring low-power operation and secure firmware update capability.

For engineers reviewing the MC908QT1AMDWE datasheet, MC908QT1AMDWE pinout, MC908QT1AMDWE application, or MC908QT1AMDWE equivalent, this page delivers verified functional identity, validated security byte handling at $FFF6–$FFFD, confirmed 8-pin SOIC-8 package mapping, and real-world substitution guidance for legacy HCS08-based designs.

Technical Context

The MC908QT1AMDWE implements the HCS08 CPU core with 16-bit address space, supports internal RC oscillator (1–8 MHz) and external crystal/RC clock sources, and features a dedicated Auto Wakeup Module (AWU) enabling ultra-low-power sleep with programmable wake intervals down to 1 ms. Its FLASH memory includes block protection and mass erase functionality.

Security enforcement operates during monitor mode entry: host must supply eight user-defined bytes matching locations $FFF6–$FFFD; entry is denied if five or more of those bytes are zero. The device uses a single 5 V supply and supports Wait/Stop low-power modes with full peripheral retention in Wait mode.

Key Specifications

Pinout & Package

MC908QT1AMDWE is housed in an 8-pin SOIC package (300 mil width) with exposed pad not present; pin functions align with the MC68HC908QTA family pin assignment table (Section 1.4, Rev. 3 datasheet).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908QT1AMDWE, both alternatives retain identical I/O structure, clocking, and security architecture but scale FLASH capacity to accommodate evolving firmware complexity - making them drop-in upgrades rather than functional substitutes.

Availability

MC908QT1AMDWE is available at Aetrix Electronics and suitable for appliance control panels, industrial timer modules, motor speed controllers, and smart power outlets requiring stable component supply across extended production lifecycles.

Supply support for MC908QT1AMDWE 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) pioneered mixed-signal microcontrollers for cost-sensitive embedded systems, emphasizing robustness, low-power design, and toolchain maturity.

The MC68HC908QTA family - including MC908QT1AMDWE - was engineered for high-volume consumer and industrial applications demanding minimal external components, secure firmware, and deterministic real-time response.

FAQ

What is the maximum operating frequency of the MC908QT1AMDWE?

The MC908QT1AMDWE supports a maximum bus clock frequency of 8 MHz, achievable either via internal RC oscillator (factory-trimmed up to 8 MHz) or external crystal/RC source. At 8 MHz bus clock, instruction execution reaches 2 million instructions per second (MIPS), sufficient for real-time control tasks in appliances and timers. The device does not support frequencies beyond 8 MHz - exceeding this may cause timing violations or undefined behavior.

Does the MC908QT1AMDWE support in-circuit debugging?

Yes, the MC908QT1AMDWE supports monitor-mode debugging through its on-chip background debug interface. Entry requires correct eight-byte security sequence written to $FFF6–$FFFD; if five or more bytes are zero, monitor mode is denied. Debugging operations include memory read/write, register inspection, and breakpoint execution - all accessible via standard BDM-compatible tools like P&E Multilink.

How is FLASH memory protected on the MC908QT1AMDWE?

FLASH protection on the MC908QT1AMDWE is implemented via the FLASH Block Protect Register (FBPROT) and mass erase lock bits. Users can configure block-level write/erase protection for specific 512-byte sectors, and disable mass erase permanently after programming. Protection remains active across power cycles and prevents accidental overwrites during field updates - critical for preserving calibration data or bootloader code in the MC908QT1AMDWE.

Can the MC908QT1AMDWE operate from a 3.3 V supply?

No, the MC908QT1AMDWE is specified only for 4.5 V to 5.5 V operation per its electrical characteristics (Section 16, Rev. 3 datasheet). It lacks 3.3 V I/O tolerance or internal voltage regulation; applying 3.3 V will result in improper CPU execution, ADC inaccuracies, and failure to enter Stop/Wait modes reliably. For 3.3 V systems, consider migrating to later-generation S08 or Kinetis devices explicitly rated for that voltage.

What is the purpose of the $FFF6–$FFFD memory locations in the MC908QT1AMDWE?

The $FFF6–$FFFD addresses in the MC908QT1AMDWE store eight user-programmable security bytes used exclusively during monitor mode entry. The host debugger must transmit matching bytes to gain access; if five or more are zero, entry is blocked. These locations are not reserved for vectors or boot code - they serve solely as a firmware security gate, and Freescale mandates programming them even when unused to prevent unintentional bypass of the MC908QT1AMDWE's security feature.