NXP Semiconductors MC68HC908MR8CP

Overview

MC68HC908MR8CP from Freescale Semiconductor is an 8-bit HCS08-core microcontroller with 8 KB on-chip FLASH, 512 B RAM, integrated 10-bit ADC (8 channels), dual 16-bit timers (TIMA/TIMB), SCI serial interface, and a dedicated 6-channel PWM motor control module (PWMMC). It operates at up to 8 MHz bus frequency and supports motor drive, industrial sensing, and embedded control in 44-pin QFP packages.

For engineers reviewing the MC68HC908MR8CP datasheet, MC68HC908MR8CP pinout, MC68HC908MR8CP application, or MC68HC908MR8CP equivalent, key selection criteria include its integrated PWMMC with dead-time insertion and fault protection, dual timer capture/compare capability, on-chip COP watchdog, and support for low-power Wait/Stop modes in resource-constrained embedded systems.

Technical Context

The MC68HC908MR8CP implements the HCS08 CPU core with enhanced addressing modes and a 16-level hardware stack. Its System Integration Module (SIM) manages clock generation, reset sequencing, and interrupt vectoring, while the Clock Generator Module (CGM) includes a PLL for precise bus clock derivation from crystal or external sources.

The Pulse-Width Modulator for Motor Control (PWMMC) provides six independent PWM outputs or three complementary pairs with programmable dead time, automatic fault shutdown via PTC0/PTC1 fault pins, and synchronized operation with TIMA/TIMB for coordinated motor phase control - all without CPU intervention.

Key Specifications

Pinout & Package

MC68HC908MR8CP is housed in a 44-pin Plastic Quad Flat Package (PQFP) with 0.8 mm lead pitch and exposed thermal pad. Pin assignments are defined per Section 1.5 of the Rev. 4.1 datasheet and validated for this specific orderable part number.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC908MR8CP, MC9RS08KA8CP offers lower static power but omits critical motor control hardware, while S9KEAZ128AMLH delivers significantly greater processing headroom and peripheral flexibility at the cost of increased design complexity and BOM cost.

Availability

MC68HC908MR8CP is available at Aetrix Electronics and suitable for industrial motor control, appliance main boards, programmable power supplies, and embedded sensor nodes requiring stable component supply across extended product lifecycles.

Supply support for MC68HC908MR8CP 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 pioneer in embedded microcontrollers, delivering high-reliability silicon for automotive, industrial, and consumer applications since 1995.

The MC68HC908MR8CP belongs to the HC08 family - designed specifically for cost-sensitive, real-time motor control and industrial automation where deterministic timing, integrated PWM, and robust fault handling are essential.

FAQ

What is the maximum bus frequency supported by the MC68HC908MR8CP?

The MC68HC908MR8CP supports a maximum bus frequency of 8 MHz, achieved via its internal Clock Generator Module (CGM) with PLL circuitry. This frequency is derived from the crystal oscillator input (1–8 MHz) and enables deterministic instruction execution for time-critical motor control loops. The actual achievable bus speed depends on VDD and ambient temperature, with full specification guaranteed across the industrial range (–40°C to +85°C) at 5.0 V.

Does the MC68HC908MR8CP include hardware-based PWM dead-time insertion?

Yes, the MC68HC908MR8CP includes dedicated hardware dead-time insertion within its Pulse-Width Modulator for Motor Control (PWMMC). This feature is programmable per complementary PWM pair and prevents simultaneous conduction in high-side/low-side FETs - a critical safety function in inverter and motor drive applications. The dead-time value is configured via the Dead-Time Write-Once Register (DTWOR) and applied automatically during complementary output transitions.

Can the MC68HC908MR8CP operate from a 3.3 V supply?

Yes, the MC68HC908MR8CP operates across a supply voltage range of 2.7 V to 5.5 V, making it fully compatible with 3.3 V systems. At 3.3 V, the maximum guaranteed bus frequency is 6 MHz (per electrical specifications in Section 21 of the Rev. 4.1 datasheet), and all I/O pins remain 5 V tolerant - simplifying interface design with legacy 5 V peripherals.

How is firmware updated on the MC68HC908MR8CP in the field?

Firmware updates for the MC68HC908MR8CP are performed via its built-in Monitor ROM (MON), accessible through the SCI interface. Using standard ASCII commands sent over UART (e.g., "P" for program, "E" for erase), users can reprogram FLASH memory without external debug hardware. The MON ROM resides in protected memory and remains active even after user code execution begins, enabling secure in-system programming.

What fault protection mechanisms does the PWMMC module provide?

The PWMMC module in the MC68HC908MR8CP provides hardware fault protection via two dedicated input pins (PTC0/PTC1) that trigger immediate, cycle-accurate PWM disable upon assertion. Fault conditions can be filtered (configurable debounce), handled in automatic mode (self-clearing after fault removal), or manual mode (requiring software acknowledgment). This ensures fail-safe motor shutdown in overcurrent, overtemperature, or short-circuit events without CPU involvement.