NXP Semiconductors MC908KX8CPE

Overview

MC908KX8CPE 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 across –40°C to +125°C and targets automotive body electronics, industrial sensor interfaces, and appliance control where robustness and low-power operation are critical.

For engineers reviewing the MC908KX8CPE datasheet, MC908KX8CPE pinout, MC908KX8CPE application, or MC908KX8CPE equivalent, key selection considerations include its 20-pin SOIC-20W package, IRQ1 external interrupt with 19–43 kΩ internal pullup, PTA0–PTA4 keyboard input pins with 24–48 kΩ pullups, stop-mode current <1 µA, and FLASH endurance of 10,000 erase/program cycles.

Technical Context

The MC908KX8CPE integrates a digitally controlled oscillator (DCO) with modulo-N divider and digital loop filter for precise internal clock generation without external crystals. Its ICG supports automatic frequency trimming and dynamic switching between internal and external clock sources, enabling reliable operation under voltage and temperature variation.

It features a dedicated Keyboard Interrupt Module (KBI) with debounced scanning of up to five keys via PTA0–PTA4, plus an External Interrupt (IRQ1) with configurable edge sensitivity and internal pullup. The 8-bit ADC includes selectable reference (VREFH), 8-channel multiplexing, and conversion times as low as 25 µs per sample.

Key Specifications

Pinout & Package

MC908KX8CPE is housed in a 20-pin SOIC-20W (wide-body) surface-mount package with 0.600-inch body width and 0.025-inch lead pitch, suitable for reflow assembly and high-reliability automotive PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908KX2CPE and MC9RS08KA2CPE, the MC908KX8CPE provides higher memory headroom for feature-rich firmware and unique KBI hardware that offloads key-scan processing - making it optimal for cost-sensitive, high-volume HMI applications requiring minimal external components.

Availability

MC908KX8CPE is available at Aetrix Electronics and suitable for automotive body control, industrial sensor nodes, and appliance HMI applications requiring stable component supply, long-term lifecycle support, and AEC-Q100-aligned qualification.

Supply support for MC908KX8CPE 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 MC908KX8CPE belongs to the M68HC08 microcontroller family, engineered for cost-sensitive, high-reliability control applications demanding integrated peripherals, wide temperature operation, and robust ESD/EMI performance.

FAQ

What is the maximum operating frequency of the MC908KX8CPE?

The MC908KX8CPE supports a maximum internal bus frequency of 8 MHz when using the internal DCO with appropriate ICG configuration. With external crystal or clock source, the device accepts up to 8 MHz input, and the internal divider allows derivation of lower frequencies for peripheral synchronization. Actual achievable speed depends on VDD and temperature - full 8 MHz operation is guaranteed at 5.0 V and 25°C per datasheet specifications.

Does the MC908KX8CPE include a hardware UART or SCI module?

No, the MC908KX8CPE does not integrate a Serial Communications Interface (SCI) module. It lacks hardware UART/USART functionality. Communication must be implemented via bit-banged GPIO or external transceivers. This distinguishes it from higher-pin-count variants like the MC68HC908GP32, which include SCI. For serial connectivity, designers typically pair the MC908KX8CPE with discrete level shifters or LIN transceivers driven by timer-generated waveforms.

Can the internal pullup resistors on PTA0–PTA4 be disabled in the MC908KX8CPE?

No, the internal pullup resistors on PTA0–PTA4 are fixed and cannot be disabled via software configuration. They are factory-trimmed to 24–48 kΩ and permanently enabled to support keyboard scanning without external components. If pullup-free operation is required, those pins must be used as outputs or isolated via external circuitry - but doing so forfeits KBI functionality for those lines.

What programming interface does the MC908KX8CPE support for FLASH programming?

MC908KX8CPE supports background programming via the on-chip monitor ROM using the standard Freescale MON08 protocol over the IRQ1 pin (used as serial data input) and the RESET pin (used as serial clock). No dedicated debug port or SWD/JTAG is present. Programming requires a compatible MON08 host tool such as the DEMO908KX8 evaluation board or third-party programmers supporting HC08 BDM/MON08 mode.

Is the MC908KX8CPE pin-compatible with other members of the KX family?

Yes, the MC908KX8CPE is pin-compatible with MC908KX2CPE and MC908KX4CPE in the same SOIC-20W package. All share identical pin assignments, electrical characteristics, and peripheral mapping. The primary differences are FLASH size (8 KB vs. 4 KB vs. 4 KB), RAM (512 B vs. 256 B), and certain fuse-configurable features - allowing drop-in replacement where memory requirements permit.