NXP Semiconductors MC908QT4AMDWE

Overview

MC908QT4AMDWE from Freescale Semiconductor is an 8-bit HCS08 microcontroller with 4 KB FLASH, 192 B RAM, internal 32 MHz RC oscillator, 10-bit ADC (8 channels), and integrated COP watchdog. It operates from 2.7–5.5 V and supports Wait/Stop low-power modes for battery-powered sensor nodes and industrial controls.

For engineers reviewing the MC908QT4AMDWE datasheet, MC908QT4AMDWE pinout, MC908QT4AMDWE application, or MC908QT4AMDWE equivalent, key selection criteria include its on-chip voltage regulator, programmable security byte protection at $FFF6–$FFFD, 16-pin SOIC-W package, and compatibility with HC08 development tools including P&E Multilink and CodeWarrior IDE.

Technical Context

The MC908QT4AMDWE implements the HCS08 CPU core with 16-bit address space, supporting indexed, extended, and relative addressing. Its memory map includes 4 KB of on-chip FLASH with block protection and EEPROM emulation, plus 192 B of RAM with automatic initialization on reset.

Peripherals include a 10-bit ADC with software-triggered conversions and configurable sample time, Auto Wakeup Module (AWU) for periodic wake-from-Stop, and Low-Voltage Inhibit (LVI) with selectable trip points (4.05 V or 3.95 V). The internal oscillator supports trimming via register OSCTRM for ±2% accuracy across temperature and voltage.

Key Specifications

Pinout & Package

MC908QT4AMDWE is housed in a 16-pin SOIC-W (Wide) package with 1.27 mm pitch, 10.3 mm body width, and JEDEC MS-013AC compliance. Pin functions are defined per MC68HC908QYA/QTA Family Data Sheet Rev. 3, Section 1.4–1.5.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908QT2AMDWE, the MC908QT4AMDWE provides +2 KB FLASH and +64 B RAM for larger control algorithms and data buffers; compared with MC908QY4ACDWE, it delivers superior low-power autonomy via trimmable RC oscillator and AWU, reducing BOM cost and standby current by 40%.

Availability

MC908QT4AMDWE is available at Aetrix Electronics and suitable for industrial sensor nodes, smart meter interfaces, and appliance control panels requiring stable component supply and long-term lifecycle support.

Supply support for MC908QT4AMDWE 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) designed high-reliability, cost-optimized 8-bit MCUs for industrial and consumer applications from 1990s through 2010s.

The MC908QT4AMDWE belongs to the HCS08 QTA family, engineered for space-constrained, battery-aware embedded systems where integration of ADC, LVI, AWU, and security features reduces external component count.

FAQ

What is the maximum bus clock frequency supported by the MC908QT4AMDWE?

The MC908QT4AMDWE supports a maximum bus clock frequency of 20 MHz, derived from its internal 32 MHz RC oscillator divided by 2 or from an external crystal source. This frequency determines instruction execution speed and peripheral timing - for example, ADC conversion time scales linearly with bus clock, and UART baud rates depend on precise clock division. The MC908QT4AMDWE achieves consistent performance across its operating voltage range without external clock components.

How does the security feature of the MC908QT4AMDWE protect firmware during programming and debugging?

The MC908QT4AMDWE implements a hardware-enforced security mechanism that prevents unauthorized access to FLASH contents in monitor mode. To enter monitor mode, the host must transmit eight security bytes matching those programmed at memory locations $FFF6–$FFFD. If five or more of these bytes are zero, monitor entry is denied. This protects firmware intellectual property during field service or third-party repair, and applies equally to the MC908QT4AMDWE and all members of the QTA family.

Can the MC908QT4AMDWE operate without an external crystal?

Yes, the MC908QT4AMDWE can operate fully from its internal 32 MHz RC oscillator, which is factory-trimmed and further adjustable via the OSCTRM register. This eliminates the need for external crystals or resonators in cost-sensitive or space-constrained designs. The internal oscillator supports all operating modes including Stop, and maintains sufficient accuracy (±2%) for UART communication at 9600 bps and ADC sampling - making the MC908QT4AMDWE viable for standalone sensor nodes where crystal reliability or EMI is a concern.

What low-power modes does the MC908QT4AMDWE support, and how do they differ?

The MC908QT4AMDWE supports two hardware low-power modes: Wait and Stop. In Wait mode, the CPU halts but peripherals (ADC, AWU, IRQ) remain clocked and functional; in Stop mode, nearly all clocks are disabled except the AWU's RC oscillator, reducing current to ~0.5 µA. Both modes retain RAM content. The MC908QT4AMDWE exits Wait on any interrupt, and Stop on AWU timeout or IRQ edge - enabling flexible power management strategies tailored to application duty cycles.

Is the MC908QT4AMDWE pin-compatible with other devices in the QTA/QYA family?

Yes, the MC908QT4AMDWE is pin-compatible with MC908QT2AMDWE and MC908QT1AMDWE in the same 16-pin SOIC-W package, sharing identical pin assignments for VDD, VSS, RESET, IRQ, PTA0–PTA7, XTAL, EXTAL, and VBAT. This allows scalable memory upgrades without PCB redesign. However, it is not pin-compatible with QY-series devices (e.g., MC908QY4ACDWE), which differ in oscillator pin functionality and internal clock routing - confirming that MC908QT4AMDWE interoperability is limited to the QT-subfamily.