NXP Semiconductors MC908QB8MDTE

Overview

MC908QB8MDTE from Freescale Semiconductor is an 8-bit M68HC08 core microcontroller with 8 KB on-chip FLASH, 512 B RAM, 10-bit ADC (8 channels), ESCI and SPI serial interfaces, and integrated oscillator. It operates at up to 8 MHz bus frequency, supports wait/stop low-power modes, and targets embedded control in automotive body electronics and industrial sensors.

For engineers reviewing the MC908QB8MDTE datasheet, MC908QB8MDTE pinout, MC908QB8MDTE application, or MC908QB8MDTE equivalent, key selection criteria include its 8 KB FLASH with user-programmable security bytes ($FFF6–$FFFD), internal RC oscillator trimming capability, and ESCI LIN-compatible serial interface for automotive network nodes.

Technical Context

The MC908QB8MDTE implements the M68HC08 CPU core with Harvard architecture, supporting 59 instructions and 16-bit addressing. Its memory map includes 8 KB FLASH (with mass/page erase and block protection), 512 B RAM, and 64 B EEPROM-like register space. The device uses a dual-clock system: internal RC oscillator (±2% accuracy after trimming) or external crystal (1–8 MHz).

Peripheral integration includes a 10-bit ADC with programmable sample time and conversion trigger sources (software, timer, ESCI), Auto Wakeup Module (AWU) for periodic wake-from-stop, and ESCI supporting asynchronous UART and LIN 1.3 physical layer timing. Security is enforced via monitor-mode entry requiring eight matching user-defined bytes at $FFF6–$FFFD - entry denied if ≥5 are zero.

Key Specifications

Pinout & Package

MC908QB8MDTE is housed in a 28-pin SOIC package (SO-28) with 24 I/O pins, 2 power pins (VDD/VSS), 2 oscillator pins (OSC1/OSC2), and dedicated reset (RES) and IRQ inputs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908QY8CDTE and MC908QB4MDTE, the MC908QB8MDTE uniquely balances 8 KB FLASH, ESCI-based LIN/UART, and KBI-driven HMI support - making it optimal for automotive body modules and industrial nodes requiring both serial networking and human interface responsiveness.

Availability

MC908QB8MDTE is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor nodes, appliance motor controllers, and portable medical instruments requiring stable component supply across multi-year production cycles.

Supply support for MC908QB8MDTE 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 and long-term support.

The MC908QB8MDTE belongs to the M68HC08 family, engineered for cost-sensitive embedded control where integrated peripherals, low-power operation, and field-programmable FLASH security meet automotive qualification standards.

FAQ

What is the maximum bus clock frequency supported by the MC908QB8MDTE?

The MC908QB8MDTE supports a maximum bus clock frequency of 8 MHz. This is achieved either via the internal trimmed RC oscillator (calibrated to ±2% accuracy) or an external crystal/resonator operating between 1–8 MHz. The bus clock drives all peripherals including the ADC, ESCI, and SPI modules, and directly determines instruction execution speed and conversion timing resolution.

How does the security feature at memory locations $FFF6–$FFFD function in the MC908QB8MDTE?

The MC908QB8MDTE implements a monitor-mode security mechanism where host tools must send eight bytes matching the user-programmed values at FLASH addresses $FFF6–$FFFD to enter monitor mode. If five or more of those bytes are zero, monitor mode entry is denied - preventing accidental or unauthorized access. These locations must be programmed even if unused as vectors, per Freescale's security guidance in the 2012 Addendum.

Does the MC908QB8MDTE support LIN 1.3 communication natively?

Yes, the MC908QB8MDTE's ESCI module provides native hardware support for LIN 1.3 physical layer timing, meeting the ±1.5% baud rate tolerance requirement without external components. The ESCI can generate and decode LIN headers and responses, enabling direct connection to automotive LIN buses when paired with a standard LIN transceiver.

What low-power modes are available on the MC908QB8MDTE and how do they differ?

The MC908QB8MDTE offers Wait and Stop modes. In Wait mode, the CPU halts but peripherals (ADC, ESCI, timers) remain clocked and functional. In Stop mode, all clocks are gated except the Auto Wakeup Module (AWU) and Low-Voltage Inhibit (LVI), reducing current to under 1 µA. Both modes support wake-up via IRQ, KBI, AWU timeout, or reset - critical for battery-operated sensor nodes.

Can the internal RC oscillator of the MC908QB8MDTE be calibrated for improved accuracy?

Yes, the MC908QB8MDTE includes an internal oscillator trim register that allows adjustment of the RC oscillator frequency across voltage and temperature variations. Factory or field calibration enables ±2% accuracy - sufficient for UART/LIN communication without requiring an external crystal, reducing BOM cost and board space.