NXP Semiconductors MC908QC16CDXE

Overview

MC908QC16CDXE from Freescale Semiconductor is an 8-bit M68HC08 core microcontroller with 16 KB on-chip FLASH, 512 B RAM, and integrated ADC10, ESCI, SPI, TIM1/TIM2, COP watchdog, and LVI reset circuitry. It operates at up to 8 MHz bus frequency with 5 V or 3.3 V supply and targets embedded control in automotive body electronics, industrial sensors, and appliance motor control.

For engineers reviewing the MC908QC16CDXE datasheet, MC908QC16CDXE pinout, MC908QC16CDXE application, or MC908QC16CDXE equivalent, key selection criteria include FLASH security byte validation ($FFF6–$FFFD), bus clock derivation (BUSCLKX4), ADC10 10-bit resolution with selectable input channels, ESCI asynchronous serial interface timing, and TSSOP-28 package compatibility with legacy HC08 toolchains.

Technical Context

The MC908QC16CDXE implements the M68HC08 CPU core with 16-bit address space, indexed addressing, and 72-instruction set optimized for deterministic real-time control. Its memory map includes 16 KB FLASH (with page/mass erase and block protection), 512 B RAM, and dedicated configuration registers (CONFIG1/CONFIG2) for oscillator mode selection and clock source routing.

Peripherals are tightly coupled via the System Integration Module (SIM): the ADC10 module supports 8-channel single-ended or 4-channel differential conversion with programmable sample time; ESCI provides full-duplex UART functionality with configurable baud rate generation using BUSCLKX4; and dual timer modules (TIM1/TIM2) support input capture, output compare, and PWM generation with independent prescalers.

Key Specifications

Pinout & Package

MC908QC16CDXE is housed in a 28-pin Thin Shrink Small Outline Package (TSSOP) with 0.65 mm pitch, compliant with JEDEC MO-153. The package supports surface-mount reflow assembly and provides thermal performance suitable for industrial ambient temperatures (–40°C to +125°C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908QC8CDXE and MC908QC4CDXE, the MC908QC16CDXE provides 2× and 4× more FLASH respectively - enabling bootloader implementation, field-upgradable features, and robust diagnostic logging without external memory.

Availability

MC908QC16CDXE is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor nodes, home appliance motor control, and legacy PLC I/O modules requiring stable component supply across extended product lifecycles.

Supply support for MC908QC16CDXE 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 8-bit microcontrollers for automotive and industrial markets, emphasizing robustness, long-term availability, and toolchain maturity.

The MC68HC908QC16 product line was designed for cost-sensitive, real-time embedded control applications requiring integrated analog peripherals, secure firmware update capability, and proven qualification for harsh environments.

FAQ

What is the maximum bus frequency supported by the MC908QC16CDXE?

The MC908QC16CDXE supports a maximum bus frequency of 8 MHz under 5 V operation, derived from internal oscillator or external crystal sources. This frequency determines instruction throughput and peripheral timing constraints - for example, ESCI baud rate accuracy and ADC conversion time scale directly with bus clock stability and speed. The MC908QC16CDXE maintains this rating across its specified industrial temperature range (–40°C to +125°C).

How does the FLASH security feature work on the MC908QC16CDXE?

The MC908QC16CDXE implements a FLASH security mechanism that blocks unauthorized access to memory contents during monitor mode. Entry requires transmission of eight user-defined security bytes matching those stored at addresses $FFF6–$FFFD. An enhanced check denies access if five or more of these bytes are zero - preventing trivial bypass attempts. This feature is enforced in hardware and cannot be disabled once programmed, making it critical to pre-load valid non-zero values before final firmware lock.

Which pins on the MC908QC16CDXE support analog-to-digital conversion?

The MC908QC16CDXE ADC10 module accepts analog inputs on PTA0–PTA3 (AD0–AD3), PTC0–PTC3 (AD4–AD7), and optionally PTC4–PTC7 depending on configuration. These pins share functions with Port A and Port C I/O, requiring proper direction register setup and ADC channel selection via ADSCR register. All eight channels support single-ended measurement with 10-bit resolution and programmable sample time - essential for accurate sensor interfacing in noisy industrial environments.

Does the MC908QC16CDXE support both 3.3 V and 5 V operation?

Yes, the MC908QC16CDXE is fully specified for operation across 2.7 V to 5.5 V supply range, including both 3.3 V and 5 V nominal systems. Electrical characteristics - such as I/O voltage thresholds, FLASH programming voltage, and ADC reference behavior - are validated at both 3.3 V and 5 V per Rev. 5 datasheet Section 19.8 and 19.5. This dual-voltage capability allows seamless integration into mixed-signal designs without level shifters, reducing BOM count and board area.

What peripheral modules are integrated into the MC908QC16CDXE?

The MC908QC16CDXE integrates the ADC10 10-bit analog-to-digital converter, ESCI asynchronous serial interface, SPI synchronous serial interface, two independent timer modules (TIM1 and TIM2), Computer Operating Properly (COP) watchdog, Low-Voltage Inhibit (LVI) reset circuit, Keyboard Interrupt (KBI), and Periodic Wakeup (PWU) module. All are managed through the System Integration Module (SIM) and share the M68HC08 bus architecture - enabling coordinated real-time control without external glue logic.