NXP Semiconductors MC908QB8CDWE

Overview

MC908QB8CDWE 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 2.7–5.5 V supply, and features flash security via $FFF6–$FFFD byte matching for monitor mode entry.

For engineers reviewing the MC908QB8CDWE datasheet, MC908QB8CDWE pinout, MC908QB8CDWE application, or MC908QB8CDWE equivalent, this page delivers verified functional architecture, validated security behavior, confirmed low-power operation modes (Wait/Stop), and precise peripheral register mapping per Rev. 3 + Addendum 5/2012.

Technical Context

The MC908QB8CDWE implements the HCS08 CPU core with 16-bit address space, 8-level hardware stack, and 72-instruction set optimized for embedded control. Its memory subsystem includes 8 KB of SuperFlash® FLASH (with mass/page erase, block protection, and 100K-cycle endurance) and 512 B of static RAM with retention in Stop mode.

Peripherals are tightly coupled via the System Integration Module (SIM): the 10-bit ADC10 supports 8-channel single-ended conversion with programmable clock division; ESCI provides LIN-compliant UART with auto-baud detection; and the Auto Wakeup Module enables event-triggered exit from low-power states using internal RC oscillator timing.

Key Specifications

Pinout & Package

MC908QB8CDWE is housed in a 28-pin SOIC (Small Outline Integrated Circuit) package with 24 I/O pins, 2 power pins (VDD/VSS), 2 oscillator pins (OSC1/OSC2), and dedicated reset (RESET) 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, MC908QB8CDWE adds KBI and larger RAM for keypad-driven HMI; versus MC908QB4CDWE, it doubles FLASH and RAM for complex control algorithms and data logging - both alternatives retain identical SOIC-28 footprint and peripheral compatibility.

Availability

MC908QB8CDWE is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor nodes, appliance control panels, and portable medical devices requiring stable component supply and long-term obsolescence management.

Supply support for MC908QB8CDWE 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 MC908QB8CDWE belongs to the HCS08 family - engineered for cost-sensitive, low-power 8-bit control applications demanding integrated analog peripherals, flash security, and robust ESD immunity in harsh environments.

FAQ

What is the maximum bus frequency supported by the MC908QB8CDWE?

The MC908QB8CDWE supports a maximum bus frequency of 8 MHz. This is achieved using the internal trimmed RC oscillator (±2% accuracy) or an external crystal source. The bus clock is derived directly from the oscillator module and governs instruction execution speed, peripheral timing, and ADC conversion rates - all verified in the Electrical Specifications chapter (Section 18) of Rev. 3 datasheet.

How does the flash security feature work on the MC908QB8CDWE?

The MC908QB8CDWE flash security feature blocks unauthorized FLASH read access during monitor mode entry unless eight user-defined bytes stored at memory locations $FFF6–$FFFD exactly match those sent by the host. An improved security function added in the May 2012 Addendum denies monitor mode entry if five or more of these bytes are $00 - preventing blank-programmed security vectors from compromising protection.

Which analog-to-digital converter channels are available on the MC908QB8CDWE?

The MC908QB8CDWE integrates a 10-bit ADC10 module with eight single-ended input channels: AD0–AD7. These map to PTA6, PTA7, PTB0–PTB5 respectively. All channels support programmable sample time, selectable reference sources (VREFH/VREFL or internal 1.25 V), and conversion triggering via software, timer, or external event - fully documented in Chapter 3 of the Rev. 3 datasheet.

Does the MC908QB8CDWE support LIN communication natively?

Yes, the MC908QB8CDWE supports LIN communication through its Enhanced Serial Communications Interface (ESCI) module. The ESCI implements LIN 1.3/2.0 physical layer compliance including break character generation, sync field detection, and auto-baud rate adjustment - confirmed in Section 13.9.3 (Bit Time Measurement) and Table 13-5 (ESCI LIN Control Bits) of Rev. 3.

What low-power modes are implemented in the MC908QB8CDWE and how do they differ?

The MC908QB8CDWE implements Wait and Stop modes. In Wait mode, the CPU halts but bus clock remains active - allowing peripherals like ADC or ESCI to operate. In Stop mode, all clocks stop except the AWU's RC oscillator, reducing current to 2.1 µA typical; wake-up occurs via IRQ, KBI, or AWU timeout. Both modes are detailed in Sections 4.5, 6.6, and 10.5 of the Rev. 3 datasheet.