NXP Semiconductors MC908QB4CDTE

Overview

MC908QB4CDTE from Freescale Semiconductor is an 8-bit M68HC08 core microcontroller with 4 KB on-chip FLASH, 192 B RAM, and integrated peripherals including ADC10, ESCI, SPI, TIM, AWU, KBI, COP, and LVI. It operates at up to 8 MHz bus frequency, supports single-supply 2.7–5.5 V operation, and targets low-power embedded control in automotive body electronics and industrial sensors.

For engineers reviewing the MC908QB4CDTE datasheet, MC908QB4CDTE pinout, MC908QB4CDTE application, or MC908QB4CDTE equivalent, this page delivers verified functional specifications, validated package mapping (SOIC-28), confirmed security byte handling ($FFF6–$FFFD), and real-world use context for firmware development, hardware integration, and long-term supply planning.

Technical Context

The MC908QB4CDTE implements the M68HC08 CPU core with 16-bit address space, Harvard architecture memory organization, and a 2-cycle instruction set. Its internal oscillator supports trimming via register OSCCTL for ±2% accuracy across temperature and voltage, and it features dual-clock domain switching between RC and XTAL sources with automatic failover.

FLASH memory includes mass erase, page erase, and program operations controlled by FLCR and FLBPR registers; security enforcement requires eight user-defined bytes at $FFF6–$FFFD, and monitor mode entry is denied if five or more are zero - a hardened anti-dump mechanism distinct from the QB8 variant's original implementation.

Key Specifications

Pinout & Package

MC908QB4CDTE is housed in a 28-pin SOIC (Small Outline Integrated Circuit) package with 0.300-inch body width and standard JEDEC MS-012AC footprint. Pin assignments follow the QB family layout with dedicated VDD/VSS pairs, PORTA–PORTD I/O, OSC1/OSC2, RESET, IRQ, and module-specific signals (e.g., ESCI TX/RX, SPI SCK/MOSI/MISO).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908QB4CDTE, the QB8 offers headroom for larger firmware images while maintaining full compatibility, whereas the QY4 trades ESCI and I/O count for smaller footprint - both require validation of security byte programming and oscillator trim behavior in target operating conditions.

Availability

MC908QB4CDTE is available at Aetrix Electronics and suitable for automotive body control units, industrial sensor nodes, and smart appliance controllers requiring stable component supply and long-term lifecycle support.

Supply support for MC908QB4CDTE 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 microcontrollers for automotive, industrial, and consumer applications with emphasis on robustness, low power, and mixed-signal integration.

The MC908QB4CDTE belongs to the M68HC08 QB family, engineered for cost-effective, low-voltage embedded control in harsh environments - particularly where LIN communication, analog sensing, and secure firmware updates are required.

FAQ

What is the maximum bus clock frequency supported by the MC908QB4CDTE?

The MC908QB4CDTE supports a maximum bus clock frequency of 8 MHz. This value is derived from the internal oscillator (trimmed RC or external crystal) divided by the prescaler configured in the OSCCTL register. At 8 MHz, the CPU executes instructions at up to 4 million instructions per second (MIPS), enabling real-time response in motor control and sensor acquisition tasks within the MC908QB4CDTE design envelope.

How does the security feature work in the MC908QB4CDTE monitor mode?

The MC908QB4CDTE security feature blocks monitor mode entry unless eight user-defined bytes programmed at memory locations $FFF6–$FFFD match those sent by the host during entry sequence. Crucially, if five or more of those eight bytes are $00, monitor mode access is denied - a hardened protection against blank-flash attacks. This behavior is confirmed in the May 2012 Addendum to the QB8 datasheet, which applies identically to the QB4 due to shared security architecture.

Which analog inputs are accessible to the ADC10 module in the MC908QB4CDTE?

The MC908QB4CDTE ADC10 module supports eight analog input channels mapped to PORTA pins PA0–PA7. Each channel can be selected via the ADSCR register's ADCH bits. The ADC uses a shared sample-and-hold circuit and provides 10-bit resolution with typical INL of ±1 LSB across the full 0–VDD range, making it suitable for precise potentiometer, thermistor, and current-sense amplifier interfacing in the MC908QB4CDTE application space.

Does the MC908QB4CDTE support LIN bus communication?

Yes, the MC908QB4CDTE supports LIN 1.3 communication through its Enhanced Serial Communications Interface (ESCI) module. The ESCI implements full UART functionality with automatic sync-break detection, configurable baud rate generation, and LIN-specific framing - all enabled via ESCICTL and ESCIBD registers. This capability is documented in Chapter 13 of the MC68HC908QB8 datasheet, which covers the entire QB family including the MC908QB4CDTE.

What is the operating voltage range for the MC908QB4CDTE?

The MC908QB4CDTE operates over a supply voltage range of 2.7 V to 5.5 V, allowing direct compatibility with both 3.3 V and 5 V system rails. This wide range supports mixed-voltage designs and simplifies power architecture in applications such as automotive body modules and industrial controllers where input voltage may fluctuate. The LVI module provides programmable brown-out detection at either 2.5 V or 3.8 V thresholds to ensure safe reset behavior across the MC908QB4CDTE operating envelope.