NXP Semiconductors MC908KX8CDWER2

Overview

MC908KX8CDWER2 from Freescale Semiconductor is an 8-bit HCS08 microcontroller featuring 8 KB on-chip FLASH, 512 B RAM, integrated 8-channel 10-bit ADC, and a programmable internal clock generator with DCO-based frequency synthesis. It operates from 4.5 V to 5.5 V across –40°C to +125°C and supports low-power wait/stop modes - used in automotive body control modules, industrial sensor interfaces, and appliance motor controllers.

For engineers reviewing the MC908KX8CDWER2 datasheet, MC908KX8CDWER2 pinout, MC908KX8CDWER2 application, or MC908KX8CDWER2 equivalent, key selection criteria include its 8 KB FLASH endurance (10k erase/write cycles), IRQ1 pullup resistor range (19–43 kΩ), PTA0–PTA4 internal pullup tolerance (24–48 kΩ), 10-bit ADC resolution with VREFH reference support, and SOIC-28 package compatibility with legacy HC08 toolchains.

Technical Context

The MC908KX8CDWER2 implements the HCS08 CPU core with 16-bit address space, supporting indexed, extended, and relative addressing modes. Its Internal Clock Generator (ICG) uses a digitally controlled oscillator (DCO) with modulo-N divider and digital loop filter for stable frequency synthesis without external crystal - enabling single-pin clock configuration via OSC1/OSC2 or external clock input.

It integrates peripheral modules including Keyboard Interrupt (KBI) for matrix scanning, SCI asynchronous serial interface, Timer Interface Module (TIM) with input capture/output compare, and Low-Voltage Inhibit (LVI) with hysteresis-triggered reset at 4.25 V (typical). All I/O ports are CMOS-compatible with configurable pullups and interrupt-on-change capability.

Key Specifications

Pinout & Package

MC908KX8CDWER2 is housed in a 28-pin SOIC (Small Outline Integrated Circuit) package with 0.600-inch body width and standard 1.27 mm pitch - compatible with automated SMT assembly and legacy HC08 socket adapters.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908KX8CDWER2, the MC908KX2CDWER2 offers identical peripheral set and pin compatibility at lower memory cost, while the MC9RS08KA2CSC trades KBI and FLASH capacity for improved active-current efficiency - making it suitable only when keyboard scanning is handled externally or omitted.

Availability

MC908KX8CDWER2 is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor nodes, and home appliance motor controllers requiring stable component supply through extended production lifecycles.

Supply support for MC908KX8CDWER2 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 MC908KX8CDWER2 belongs to the HCS08 family - engineered for cost-sensitive, high-reliability 8-bit control applications where flash endurance, wide temperature operation, and peripheral integration are prioritized over raw speed.

FAQ

What is the maximum operating frequency of the MC908KX8CDWER2?

The MC908KX8CDWER2 supports a maximum system clock frequency of 20 MHz when using the internal DCO with appropriate trimming. This is achieved via the ICG module's digitally controlled oscillator and modulo-N divider, and does not require an external crystal. The actual achievable frequency depends on VDD and temperature, with guaranteed operation up to 16 MHz across the full –40°C to +125°C range per datasheet specifications. MC908KX8CDWER2 maintains timing compliance under these conditions.

Does the MC908KX8CDWER2 support in-circuit programming?

Yes, the MC908KX8CDWER2 supports in-circuit programming via its built-in monitor ROM and single-wire background debug mode (BDM). Programming is performed using the BKGD pin (shared with PTB1) and requires a compatible Freescale/NXP BDM debugger. FLASH memory can be reprogrammed in-system without removing the MC908KX8CDWER2 from the target board, enabling field firmware updates and development iteration.

What ADC reference options are available on the MC908KX8CDWER2?

The MC908KX8CDWER2 ADC supports two reference configurations: VDD as the default reference (ratiometric to supply), or an external voltage applied to the VREFH pin - which must be ≤ VDD and ≥ 2.5 V. Using VREFH decouples ADC accuracy from VDD fluctuations, improving measurement stability in noisy power environments. The ADC does not support internal bandgap reference; all conversions rely on these two externally defined references. MC908KX8CDWER2 requires proper bypassing of VREFH for optimal 10-bit linearity.

Can the MC908KX8CDWER2 operate without an external crystal?

Yes, the MC908KX8CDWER2 can operate without an external crystal by using its internal Digitally Controlled Oscillator (DCO) as the system clock source. The DCO is factory-trimmed and further adjustable via the ICG Trim Register, delivering stable frequencies from 1 MHz to 20 MHz. Crystal-less operation reduces component count and cost, and is commonly used in applications where absolute timing precision is less critical than cost and simplicity. MC908KX8CDWER2 retains full functionality including ADC, SCI, and TIM in this mode.

What is the purpose of the IRQ1 pin on the MC908KX8CDWER2?

The IRQ1 pin on the MC908KX8CDWER2 is a dedicated, edge-sensitive external interrupt input with an internal pullup resistor (19–43 kΩ). It is used to wake the MCU from wait or stop mode, trigger time-critical event handling (e.g., emergency stop), or synchronize with external signals such as encoder pulses or sensor alerts. Unlike general-purpose I/O pins, IRQ1 has dedicated hardware priority and latency guarantees - ensuring sub-1 µs response from interrupt assertion to vector fetch. MC908KX8CDWER2 supports both rising and falling edge configuration via the IRQSC register.