NXP Semiconductors MC68HC908LB8CPE

Overview

MC68HC908LB8CPE from NXP (formerly Freescale) is an 8-bit HCS08-core microcontroller with 8 KB on-chip FLASH, 512 B RAM, integrated 8-channel 10-bit ADC, dual op-amp/comparator module, and high-resolution PWM (HRP) with dithering and deadtime control. It operates at up to 8 MHz bus frequency and targets low-power motor control and sensor interface applications in industrial and appliance systems.

For engineers reviewing the MC68HC908LB8CPE datasheet, MC68HC908LB8CPE pinout, MC68HC908LB8CPE application, or MC68HC908LB8CPE equivalent, key selection criteria include its HRP dithering capability for EMI reduction, on-chip analog front-end integration, COP watchdog reliability, LVI brownout protection, and compatibility with legacy HC08 development tools.

Technical Context

The MC68HC908LB8CPE implements the CPU08 core with 16-bit address space, supporting indexed, extended, and relative addressing modes. Its memory map includes 8 KB FLASH (with block protection), 512 B RAM, and dedicated register space for peripheral modules including HRP, ADC, KBI, and TIM.

It integrates a dual op-amp/comparator module usable for signal conditioning and zero-crossing detection, and features a High Resolution PWM (HRP) subsystem capable of variable-frequency or variable-duty-cycle operation with programmable deadtime insertion and frequency dithering-enabling precise timing control and reduced electromagnetic interference in motor drive stages.

Key Specifications

Pinout & Package

MC68HC908LB8CPE is housed in a 48-pin QFP (Quad Flat Package) with 0.5 mm pitch, compliant with JEDEC MS-026. Pin assignments are defined per Section 1.4 (Pin Assignments) and Section 1.5 (Pin Functions) of the Rev. 1 datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC9RS08KA8CFD and S9KEAZ128AMLH, the MC68HC908LB8CPE uniquely combines HRP dithering, dual op-amps, and COP/LVI in a single 48-pin QFP - making it irreplaceable for cost-sensitive, EMI-constrained motor control where analog integration reduces component count and layout complexity.

Availability

MC68HC908LB8CPE is available at Aetrix Electronics and suitable for industrial motor control, appliance user-interface systems, and sensor signal-conditioning applications requiring stable component supply and long-term manufacturing continuity.

Supply support for MC68HC908LB8CPE 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

NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT markets.

The MC68HC908LB8CPE belongs to the legacy HCS08 microcontroller family, designed specifically for cost-effective, low-power embedded control in appliances, motor drives, and industrial equipment where analog integration and deterministic timing are critical.

FAQ

What is the maximum operating frequency of the MC68HC908LB8CPE?

The MC68HC908LB8CPE supports a maximum bus frequency of 8 MHz, derived from its internal oscillator or external crystal source. This frequency defines the instruction execution rate and timing resolution for peripherals like the HRP and ADC. The CPU08 core executes most instructions in 1–3 bus cycles, enabling predictable real-time response in control applications. System timing must account for oscillator tolerance and load capacitance when using external crystals.

Does the MC68HC908LB8CPE include on-chip debug support?

Yes, the MC68HC908LB8CPE includes background debug mode (BDM) support via a dedicated BKGD pin, enabling non-intrusive program download, breakpoint setting, and register inspection during development. This capability is documented in Chapter 19 (Development Support) of the datasheet and requires a compatible BDM pod or debugger. No external JTAG adapter is needed, simplifying early-stage firmware validation and field updates.

How does the High Resolution PWM (HRP) module differ from standard PWM in the MC68HC908LB8CPE?

The HRP module in the MC68HC908LB8CPE provides sub-100 ns timing resolution, programmable deadtime insertion (1–127 bus cycles), and frequency dithering - features absent in the standard PWM module. Unlike basic PWM, HRP supports both variable-frequency and variable-duty-cycle modes, with dedicated registers for period, duty cycle, and dithering control. These capabilities are essential for reducing EMI in half-bridge motor drivers and ensuring safe switching transitions.

Can the MC68HC908LB8CPE operate from a single 3.3 V supply?

Yes, the MC68HC908LB8CPE operates across a 2.7–5.5 V supply range, fully supporting 3.3 V nominal operation. At 3.3 V, it maintains full functionality including 8 MHz bus speed, ADC accuracy, and HRP timing resolution. Designers must ensure adequate decoupling (e.g., 100 nF ceramic + 4.7 µF tantalum) near VDD/VSS pins to maintain analog stability and digital noise immunity, especially when driving external MOSFET gates.

What analog peripherals are integrated into the MC68HC908LB8CPE?

The MC68HC908LB8CPE integrates an 8-channel 10-bit ADC, a dual op-amp/comparator module (two independent units), and a Low-Voltage Inhibit (LVI) circuit. The ADC supports software- or timer-triggered conversions with configurable sample time. Each op-amp/comparator can be configured independently for gain, hysteresis, or open-drain output - enabling direct connection to sensors, current shunts, or zero-crossing detectors without external signal conditioning components.