NXP Semiconductors MC908QB8CPE

Overview

MC908QB8CPE from Freescale Semiconductor is an 8-bit HCS08-core microcontroller with 8 KB on-chip FLASH, 512 B RAM, and integrated peripherals including ADC10, ESCI, SPI, TIM, AWU, COP, and KBI. It operates at up to 8 MHz bus frequency, supports 3.0–5.5 V supply, and features programmable security bytes at $FFF6–$FFFD for monitor-mode access control.

For engineers reviewing the MC908QB8CPE datasheet, MC908QB8CPE pinout, MC908QB8CPE application, or MC908QB8CPE equivalent, this page delivers verified technical context, real-world use cases, validated alternatives, and supply-chain-ready availability details - all grounded in Freescale's official MC68HC908QB8 Rev. 3 and Addendum 5/2012 documentation.

Technical Context

The MC908QB8CPE implements the HCS08 CPU core with 16-bit addressing, a 10-bit successive-approximation ADC (ADC10) with 8 input channels, and dual-clock domain support (internal RC oscillator + external crystal). Its enhanced serial interface (ESCI) supports asynchronous UART and LIN 1.3 communication.

Security enforcement occurs 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 $00. The device includes low-power modes (Wait/Stop), COP watchdog, LVI reset protection, and keyboard interrupt capability across PORTA pins.

Key Specifications

Pinout & Package

MC908QB8CPE is housed in a 28-pin SOIC package (SO-28) with 24 I/O pins, power/ground, oscillator, reset, and dedicated module pins (e.g., ESCI TX/RX, SPI SCK/MOSI/MISO, ADC inputs).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908QB8CPE, MC908QY8CDT offers smaller size but sacrifices ESCI-based LIN communication, while MC9RS08KA8CP provides better power efficiency and debug capability at the cost of legacy peripheral compatibility - making MC908QB8CPE optimal for cost-sensitive, LIN-integrated, and keyboard-driven legacy platforms.

Availability

MC908QB8CPE is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor nodes, appliance user interfaces, and portable medical diagnostic tools requiring stable component supply across extended production lifecycles.

Supply support for MC908QB8CPE 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) was a leading designer of embedded processors, analog, and mixed-signal ICs for automotive, industrial, and consumer markets.

The MC68HC908QB8 family targets cost-sensitive, low-power 8-bit control applications where integrated analog, serial, and security features reduce system complexity - especially in automotive sub-systems and white-goods controllers.

FAQ

What is the maximum bus frequency supported by the MC908QB8CPE?

The MC908QB8CPE supports a maximum bus frequency of 8 MHz. This is achieved using the internal RC oscillator trimmed to ±2% accuracy or an external crystal up to 8 MHz, with the BUSCLKX4 signal providing the base clock for CPU and peripheral timing. The actual operating frequency depends on oscillator selection and configuration register settings in the OSC module.

Does the MC908QB8CPE include hardware support for LIN communication?

Yes, the MC908QB8CPE includes an Enhanced Serial Communications Interface (ESCI) module that fully supports LIN 1.3 protocol in master and slave modes. Its baud rate generator, break detection, and sync field handling are implemented in hardware - enabling robust, low-cost LIN networking without external transceivers beyond the physical layer.

How does the flash security mechanism work on the MC908QB8CPE?

The MC908QB8CPE enforces flash security during monitor mode entry: the host must send eight bytes matching the user-programmed values stored at memory addresses $FFF6–$FFFD. If five or more of those bytes are $00, monitor mode entry is denied - preventing unauthorized firmware readout or reprogramming in production environments.

Can the MC908QB8CPE operate from a 3.3 V supply?

Yes, the MC908QB8CPE operates across a supply range of 3.0 V to 5.5 V, making it compatible with standard 3.3 V logic systems. All I/O pins are 5 V tolerant when configured as inputs, and internal regulators ensure stable core voltage regardless of VDD level - simplifying integration into mixed-voltage designs.

What low-power modes are available on the MC908QB8CPE?

The MC908QB8CPE supports Wait and Stop modes. In Wait mode, the CPU halts while peripherals remain active; in Stop mode, nearly all clocks stop, reducing current to under 1 µA. Both modes support wake-up via IRQ, KBI, or AWU timeout - enabling energy-efficient operation in battery-powered applications.