NXP Semiconductors MC68HC908GT8CB

Overview

MC68HC908GT8CB from NXP (formerly Freescale) is an 8-bit HCS08-core microcontroller with 8 KB on-chip Flash memory, 512 B RAM, and integrated peripherals including 8-channel 10-bit ADC, ESCI serial interface, SPI, TIM, TBM, KBI, and COP watchdog. It operates at up to 8 MHz bus frequency and supports 3.0–5.5 V supply, targeting low-cost embedded control in industrial sensors and appliance subsystems.

For engineers reviewing the MC68HC908GT8CB datasheet, MC68HC908GT8CB pinout, MC68HC908GT8CB application, or MC68HC908GT8CB equivalent, key selection criteria include its 28-pin SOIC package, internal clock generator with DCO+PLL architecture, flash programmability in-system, and support for low-power wait/stop modes with wake-on-IRQ/KBI.

Technical Context

The MC68HC908GT8CB implements the CPU08 core with 16-bit address space, indexed addressing, and 72-instruction set optimized for compact code. Its Internal Clock Generator (ICG) combines a digitally controlled oscillator (DCO), modulo-N divider, and frequency comparator to achieve ±4% accuracy without external crystal-enabling cost-sensitive designs.

Peripherals are tightly integrated via the System Integration Module (SIM): the ESCI supports asynchronous full-duplex UART operation at up to 115.2 kbps; the 8-channel ADC provides configurable sample time and reference selection (VREFH/VREFL); and the Keyboard Interrupt Module (KBI) enables debounced matrix scanning with automatic wake-from-stop capability.

Key Specifications

Pinout & Package

MC68HC908GT8CB is housed in a 28-pin SOIC (Small Outline Integrated Circuit) package with 0.300-inch body width and standard JEDEC MS-012AC footprint. Pin assignments are defined per Rev. 5.0 datasheet Section 1.4 and validated for this variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC908GT16CB, the MC68HC908GT8CB offers identical peripheral functionality at reduced Flash capacity-ideal for stable, mature designs. Versus MC9RS08KA8CFKR, it lacks SWD but maintains broader legacy tool compatibility and proven field reliability in cost-constrained deployments.

Availability

MC68HC908GT8CB is available at Aetrix Electronics and suitable for industrial sensor nodes, home appliance control panels, and smart power outlets requiring stable component supply across multi-year production cycles.

Supply support for MC68HC908GT8CB 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 applications, with roots in Freescale's embedded controller heritage.

The MC68HC908GT8CB belongs to the HCS08 microcontroller family, designed specifically for cost-sensitive, low-power embedded control applications requiring high integration and field-proven reliability in harsh environments.

FAQ

What is the maximum operating frequency of the MC68HC908GT8CB?

The MC68HC908GT8CB supports a maximum bus frequency of 8 MHz, achieved via its internal clock generator (ICG) using the digitally controlled oscillator (DCO) and PLL multiplier. This frequency determines instruction execution speed and peripheral timing budgets, and is fully specified across the –40 °C to +85 °C temperature range per Rev. 5.0 datasheet Section 20.8.

Does the MC68HC908GT8CB support in-system programming (ISP)?

Yes, the MC68HC908GT8CB supports in-system programming via its on-chip Flash memory. The device implements page erase, mass erase, and program/read operations accessible through standard background debug mode (BDM) interface, enabling firmware updates without removing the MC68HC908GT8CB from the target board.

What ADC reference options are available on the MC68HC908GT8CB?

The MC68HC908GT8CB ADC supports two reference configurations: external differential reference using dedicated VREFH and VREFL pins, or internal bandgap reference (1.25 V typical) selected via ADCSC1 register. This flexibility allows precise sensor measurement across varying supply conditions without external voltage references.

How does the Keyboard Interrupt Module (KBI) function on the MC68HC908GT8CB?

The KBI on the MC68HC908GT8CB monitors Port A pins (PTA7–PTA0) for transitions and generates interrupts on configurable edges. It includes hardware debouncing and can wake the MC68HC908GT8CB from Stop mode, making it ideal for low-power keypad interfaces where CPU sleep must be maintained until user input occurs.

Is the MC68HC908GT8CB pin-compatible with the MC68HC908GT16CB?

Yes, the MC68HC908GT8CB and MC68HC908GT16CB share identical 28-pin SOIC packaging, pin assignments, and peripheral signal mapping per datasheet Rev. 5.0 Section 1.4. The only functional difference is Flash capacity (8 KB vs. 16 KB), allowing direct substitution in existing layouts when firmware size permits.