NXP Semiconductors MC68HC908AB32MPB

Overview

MC68HC908AB32MPB from NXP (formerly Freescale) is an 8-bit HCS08 microcontroller with 32 KB on-chip FLASH, 1 KB RAM, and 512 B EEPROM. It integrates dual 16-bit timer modules (TIMA/TIMB), a 10-bit 8-channel ADC, SCI and SPI serial interfaces, and a PLL-based clock generator supporting up to 8 MHz bus frequency. It targets low-cost industrial control and sensor interface applications requiring deterministic real-time response.

For engineers reviewing the MC68HC908AB32MPB datasheet, MC68HC908AB32MPB pinout, MC68HC908AB32MPB application, or MC68HC908AB32MPB equivalent, key selection criteria include its 32 KB FLASH endurance (10K erase/write cycles), integrated COP watchdog, LVI reset protection, and 48-pin QFP package with configurable I/O ports including keyboard interrupt (KBI) support.

Technical Context

The MC68HC908AB32MPB implements the HCS08 CPU core with 16-bit index register, 8-bit accumulator, and condition-code-based branching. Its System Integration Module (SIM) manages reset sources-including POR, LVI, COP timeout, and illegal opcode-and coordinates low-power Wait/Stop modes with wake-up via IRQ, KBI, or SCI.

The Clock Generator Module (CGM) includes a crystal oscillator input (OSC1/OSC2), PLL with programmable bandwidth, and CGMXFC filter capacitor terminal for stable frequency synthesis. The ADC supports single-ended or differential inputs with configurable sample time and conversion trigger sources including TIMA/TIMB compare events.

Key Specifications

Pinout & Package

MC68HC908AB32MPB is housed in a 48-pin QFP (quad flat pack) package with 0.5 mm lead pitch, designed for surface-mount assembly and thermal reliability in industrial ambient conditions. Pin functions are defined per Section 1.6 of the Freescale MC68HC908AB32 Technical Data Rev. 1.1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC9RS08KA8CP, the MC68HC908AB32MPB delivers higher integration for mid-tier control tasks; compared with S9KEAZ128AMLH, it offers lower BOM cost and simpler development for legacy 8-bit firmware ecosystems without needing ARM toolchains or certification.

Availability

MC68HC908AB32MPB is available at Aetrix Electronics and suitable for industrial motor control, smart sensor nodes, appliance UIs, and programmable power supplies requiring stable component supply and long-term production continuity.

Supply support for MC68HC908AB32MPB 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 specializing in secure connectivity solutions for automotive, industrial, and IoT markets, with roots in Freescale's microcontroller heritage.

The MC68HC908AB32MPB belongs to the HCS08 family, designed for cost-sensitive, real-time embedded control applications where deterministic timing, low power, and peripheral integration outweigh raw processing throughput.

FAQ

What is the maximum operating frequency of the MC68HC908AB32MPB?

The MC68HC908AB32MPB achieves a maximum bus frequency of 8 MHz using its integrated Phase-Locked Loop (PLL), which multiplies a 32.768 kHz crystal input. This frequency governs instruction execution, timer increments, and peripheral timing. The core operates at bus speed, delivering deterministic real-time performance suitable for motor control and sensor acquisition loops. The MC68HC908AB32MPB does not support frequencies beyond 8 MHz under standard operating conditions.

Does the MC68HC908AB32MPB support in-circuit programming without a dedicated debugger?

Yes, the MC68HC908AB32MPB includes a built-in Monitor ROM (MON) that enables in-system programming via its SCI interface using only a UART connection and host PC software. This eliminates the need for external debug probes during firmware updates. The MON supports memory read/write, register access, and secure bootloader functions. The MC68HC908AB32MPB's MON is factory-programmed and remains functional across all operating voltages and temperatures.

How many analog input channels does the ADC in the MC68HC908AB32MPB support?

The MC68HC908AB32MPB features a 10-bit successive-approximation ADC with eight single-ended input channels (ATD0–ATD7), mapped to Port B pins PTB0–PTB7. It also supports differential input configurations using selected channel pairs. Conversion time is fixed at 25 µs per sample, and triggers can originate from software, TIMA/TIMB compare events, or periodic interrupts. The MC68HC908AB32MPB's ADC includes dedicated VREFH and AVSS/VREFL pins for precise external reference control.

What low-power modes are available on the MC68HC908AB32MPB?

The MC68HC908AB32MPB supports two hardware low-power modes: Wait mode (CPU halted, peripherals active, wake-up via IRQ/KBI/SCI) and Stop mode (all clocks stopped except LVI and reset logic, wake-up via IRQ/RST). Both modes reduce current consumption significantly-Stop mode draws less than 1 µA typical. Wake-up latency is under 4 µs from Wait mode and ~100 µs from Stop mode. The MC68HC908AB32MPB maintains RAM and register contents across both modes.

Is the MC68HC908AB32MPB pin-compatible with other HCS08 family members?

No, the MC68HC908AB32MPB is not pin-compatible with other HCS08 devices due to its unique 48-pin QFP footprint and specific peripheral pin mappings-for example, TIMB channel 3 is assigned to PTF3, while other variants assign different functions to that pin. While software may be portable within the HCS08 architecture, PCB layout must be designed specifically for the MC68HC908AB32MPB. The MC68HC908AB32MPB datasheet (Section 1.5) defines its exclusive pin assignments and cannot be substituted without board revision.