NXP Semiconductors MC908KX8MDWE

Overview

MC908KX8MDWE from Freescale Semiconductor is an 8-bit M68HC08 core microcontroller with 8 KB on-chip FLASH, 512 B RAM, integrated 8-channel 8-bit ADC, and programmable internal clock generator (ICG) supporting DCO-based frequency synthesis. It operates from 4.5 V to 5.5 V over –40°C to +125°C and targets automotive body electronics, industrial sensor interfaces, and low-cost motor control.

For engineers reviewing the MC908KX8MDWE datasheet, MC908KX8MDWE pinout, MC908KX8MDWE application, or MC908KX8MDWE equivalent, key selection criteria include its 8-bit CPU performance at up to 8 MHz, on-chip FLASH endurance (10k erase/write cycles), IRQ1 external interrupt with 19–43 kΩ pullup, KBI keyboard scan capability, and LVI reset threshold at 4.25 V nominal.

Technical Context

The MC908KX8MDWE integrates a digitally controlled oscillator (DCO) with modulo-N divider and digital loop filter for stable internal clock generation without external crystal. Its ICG supports automatic frequency trimming and clock monitor circuitry for fail-safe operation in harsh environments.

It features a dedicated Keyboard Interrupt Module (KBI) with configurable debounce and edge detection across PTA4–PTA0, plus an 8-channel single-ended ADC with programmable conversion time (16–64 µs) and reference selectable between VREFH and VDD. The device includes COP watchdog with selectable timeout and low-voltage inhibit (LVI) with hysteresis.

Key Specifications

Pinout & Package

MC908KX8MDWE is housed in a 28-pin SOIC (Small Outline Integrated Circuit) package with 300 mil width, JEDEC MS-012AC compliant, and lead-free (Pb-free) finish per RoHS.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908KX2MDWE and MC9RS08KA2CSC, the MC908KX8MDWE provides the largest on-chip memory and full KBI support in the KX family, making it optimal for feature-rich body electronics where code growth headroom and hardware key scanning are essential.

Availability

MC908KX8MDWE is available at Aetrix Electronics and suitable for automotive body control, industrial sensor interface, and appliance motor control applications requiring stable component supply and long-term industrial lifecycle support.

Supply support for MC908KX8MDWE 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) is a global leader in embedded processing solutions, specializing in automotive, industrial, and networking microcontrollers.

The MC908KX8MDWE belongs to the M68HC08 family, designed for cost-sensitive, high-reliability 8-bit control applications in harsh environments - emphasizing robustness, integrated analog peripherals, and automotive qualification.

FAQ

What is the maximum operating frequency of the MC908KX8MDWE?

The MC908KX8MDWE supports a maximum bus frequency of 8 MHz, achievable using the internal digitally controlled oscillator (DCO) or external crystal up to 8 MHz. Its instruction cycle time is 40 ns at this rate, enabling real-time response in motor control and sensor acquisition tasks. The ICG module allows dynamic frequency adjustment with settling time under 100 µs.

Does the MC908KX8MDWE include a hardware watchdog timer?

Yes, the MC908KX8MDWE includes a Computer Operating Properly (COP) module functioning as a configurable watchdog timer. It offers eight timeout options ranging from 0.5 ms to 1.6 s, programmable via the COPCTL register. The COP must be periodically cleared by firmware; failure triggers a hardware reset, ensuring system recovery from runaway code or hang conditions.

Can the MC908KX8MDWE operate without an external crystal?

Yes, the MC908KX8MDWE can operate without an external crystal using its internal digitally controlled oscillator (DCO). The ICG module provides factory-trimmed DCO operation at nominal frequencies (e.g., 4 MHz or 8 MHz), with optional software trimming for improved accuracy. External crystal is optional and used only when higher frequency stability is required.

What is the function of the IRQ1 pin on the MC908KX8MDWE?

The IRQ1 pin on the MC908KX8MDWE is a dedicated external interrupt input that supports edge-triggered (rising or falling) interrupts. It features an internal pullup resistor of 19–43 kΩ, eliminating the need for an external pullup in open-drain or switch-based interfaces. IRQ1 is commonly used for emergency stop signals, encoder zero-crossing detection, or fault flag inputs.

Is the MC908KX8MDWE qualified for automotive applications?

Yes, the MC908KX8MDWE is AEC-Q100 qualified for automotive applications and specified for operation from –40°C to +125°C. Its integrated LVI circuit, extended voltage range (4.5–5.5 V), and robust I/O structure meet requirements for body electronics modules such as door controllers, seat adjusters, and lighting drivers deployed in passenger vehicles.