NXP Semiconductors MC68HC908MR16CB

Overview

MC68HC908MR16CB from Freescale Semiconductor is an 8-bit HCS08-core microcontroller with 16 KB on-chip FLASH, 512 B RAM, and integrated motor control peripherals including six-channel PWM with dead-time insertion and complementary output modes. It features a PLL-based clock generator, 10-bit ADC with 12 input channels, and dual timer interfaces (TIMA/TIMB) for precise timing in embedded motor drive applications.

For engineers reviewing the MC68HC908MR16CB datasheet, MC68HC908MR16CB pinout, MC68HC908MR16CB application, or MC68HC908MR16CB equivalent, this page delivers verified functional identity, validated package mapping (SOIC-48), confirmed I/O configuration (PTA–PTF), real-time PWM timing behavior, and direct alternative options for legacy HCS08 motor control designs.

Technical Context

The MC68HC908MR16CB implements the HCS08 CPU core with 20 MHz maximum bus frequency, supported by a programmable PLL that accepts 1–8 MHz crystal inputs and generates internal clocks up to 40 MHz. Its memory subsystem includes 16 KB FLASH with block protection (FLBPR at $FF7E), 512 B RAM, and 2 KB ROM monitor for in-circuit programming.

Motor control functionality is centralized in the PWMMC module: six independent PWM outputs (PWM1–PWM6) support both standalone and complementary pair configurations with configurable dead-time (1–128 system clock cycles), top/bottom correction based on phase current polarity, and fault shutdown via PTD[3:0] inputs. The ADC provides 12-channel, 10-bit conversion with programmable sample time and result justification.

Key Specifications

Pinout & Package

MC68HC908MR16CB is housed in a 48-pin SOIC package (JEDEC MS-013AC), with 44 active I/O pins distributed across Ports A–F, plus dedicated power, reset, oscillator, and PWM ground terminals.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC908MR16CB, the MR32CB offers doubled FLASH capacity while maintaining identical peripheral functionality and pin compatibility-ideal for firmware growth. The S9KEAZ128AMLH provides modern ARM architecture, CAN, and larger memory but requires full hardware and software redesign.

Availability

MC68HC908MR16CB is available at Aetrix Electronics and suitable for brushless DC motor drives, HVAC blower systems, appliance pump controllers, and automotive auxiliary pump applications requiring stable component supply and long-term industrial lifecycle support.

Supply support for MC68HC908MR16CB 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) pioneered embedded controller solutions for automotive and industrial markets with emphasis on reliability and real-time performance.

The MC68HC908MR16CB belongs to the HCS08 microcontroller family designed specifically for cost-sensitive, high-volume motor control applications requiring integrated PWM, ADC, and fault handling in compact packages.

FAQ

What is the maximum bus frequency supported by the MC68HC908MR16CB?

The MC68HC908MR16CB supports a maximum bus frequency of 20 MHz, achieved via its integrated PLL clock generator that multiplies a 1–8 MHz crystal input. This frequency determines instruction execution speed, ADC sampling rate, and PWM resolution limits. All timing-critical peripherals-including TIMA, TIMB, and PWMMC-are synchronized to this bus clock, making it the fundamental timing reference for the entire MC68HC908MR16CB system.

Does the MC68HC908MR16CB include hardware support for complementary PWM outputs with dead-time insertion?

Yes, the MC68HC908MR16CB's PWMMC module natively supports complementary PWM pair generation with programmable dead-time insertion ranging from 1 to 128 system clock cycles. This feature is implemented in hardware and operates independently of CPU intervention, ensuring deterministic timing and eliminating shoot-through risk in half-bridge or inverter gate drive circuits. Dead-time is configured per PWM pair using dedicated control registers within the MC68HC908MR16CB's SIM module.

How many analog input channels does the ADC in the MC68HC908MR16CB support?

The MC68HC908MR16CB integrates a 10-bit successive approximation ADC with 12 configurable analog input channels. These are mapped across Port B (ATD0–ATD7), Port C (ATD8–ATD9), and dedicated pins (VREFH/VREFL). Channel selection, sample time, and conversion trigger source (software, timer, or external event) are fully programmable. The ADC supports both left-justified and right-justified 10-bit results stored across two 8-bit registers (ADRH/ADRL) in the MC68HC908MR16CB memory map.

What package type and pin count does the MC68HC908MR16CB use?

The MC68HC908MR16CB is packaged in a 48-pin SOIC (Small Outline Integrated Circuit) with JEDEC MS-013AC mechanical dimensions (0.600-inch body width). This surface-mount package supports automated PCB assembly and provides 44 usable I/O pins across Ports A–F, plus dedicated power, reset, oscillator, and PWM ground terminals. Pin assignments are documented in Section 1.4 ("Pin Assignments") of the MC68HC908MR16CB datasheet Rev. 6.1.

Is there an on-chip ROM monitor in the MC68HC908MR16CB for in-system programming?

Yes, the MC68HC908MR16CB includes a 2 KB ROM monitor located at fixed memory addresses, enabling in-system programming (ISP) via the Serial Communications Interface (SCI) without requiring external debug hardware. This monitor supports FLASH programming, verification, and erasure commands and is activated via the RST pin with specific IRQ timing sequences. It eliminates the need for dedicated programming headers in production designs and is accessible throughout the MC68HC908MR16CB's operational lifetime.