NXP Semiconductors MC68HC908GT16CB

Overview

MC68HC908GT16CB from NXP (formerly Freescale) is an 8-bit HCS08-core microcontroller with 16 KB on-chip Flash memory, 512 B RAM, and integrated peripherals including 10-bit ADC, ESCI, SPI, TIM, KBI, and COP watchdog. It operates at up to 8 MHz bus frequency, supports 3.0–5.5 V supply, and targets embedded control in industrial sensors and appliance motor interfaces.

For engineers reviewing the MC68HC908GT16CB datasheet, MC68HC908GT16CB pinout, MC68HC908GT16CB application, or MC68HC908GT16CB equivalent, key selection criteria include its 40-pin SOIC package, internal clock generator with DCO trim capability, 8-channel 10-bit ADC with external reference support, and dual low-power modes (Wait/Stop) with wake-up via IRQ, KBI, or reset.

Technical Context

The MC68HC908GT16CB implements the HCS08 CPU core with 16-bit address space, indexed addressing, and 72-instruction set optimized for compact code. Its Internal Clock Generator (ICG) integrates a digitally controlled oscillator (DCO), modulo-N divider, frequency comparator, and digital loop filter to achieve ±4% accuracy across voltage and temperature without external crystal.

Peripherals are tightly coupled via the System Integration Module (SIM): ESCI supports asynchronous serial communication with programmable baud rate; SPI enables master/slave synchronous data exchange; TIM provides input capture, output compare, and PWM generation; and KBI delivers low-power keyboard scanning with configurable debounce and interrupt-on-change.

Key Specifications

Pinout & Package

MC68HC908GT16CB is housed in a 40-pin SOIC (Small Outline Integrated Circuit) package with 0.75 mm pitch, JEDEC MS-012AC compliant, suitable for automated SMT assembly and thermal management in compact PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC9RS08KA8 and MC9S08QG8, the MC68HC908GT16CB offers double the Flash capacity, full SPI/ESCI feature parity, and 2× bus frequency - making it the only option among the three capable of supporting complex sensor fusion firmware and real-time motor control loops.

Availability

MC68HC908GT16CB is available at Aetrix Electronics and suitable for industrial sensor interface, home appliance motor control, smart meter front-end, and factory automation I/O modules requiring stable component supply across extended product lifecycles.

Supply support for MC68HC908GT16CB 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 heritage from Freescale's microcontroller division.

The MC68HC908GT16CB belongs to the HCS08 family, designed specifically for cost-sensitive, low-power embedded control applications requiring robust analog integration, deterministic real-time response, and long-term supply assurance.

FAQ

What is the maximum operating frequency of the MC68HC908GT16CB?

The MC68HC908GT16CB supports a maximum bus frequency of 8 MHz, achieved via its internal clock generator (ICG) with digitally controlled oscillator (DCO) and programmable multiplier. This frequency defines the instruction execution rate and timing margins for all on-chip peripherals including ADC conversion time, ESCI baud rate generation, and TIM counter resolution. The ICG allows dynamic clock scaling and supports external crystal up to 8 MHz for enhanced stability when required.

Does the MC68HC908GT16CB support external crystal oscillators?

Yes, the MC68HC908GT16CB supports external crystal or ceramic resonator connections on PTE4/OSC1 and PTE3/OSC2 pins. The oscillator circuit is configurable via the CONFIG register to enable either crystal mode (XTAL) or external clock input (EXTCLK). When enabled, the crystal oscillator operates in fundamental mode with load capacitance matching typical 1–8 MHz crystals, providing higher frequency accuracy than the internal DCO for applications requiring tight timing compliance.

How many analog input channels does the MC68HC908GT16CB ADC support?

The MC68HC908GT16CB integrates a 10-bit successive approximation ADC with 8 analog input channels mapped to PTB7–PTB0 pins. These channels share a common sample-and-hold circuit and are selected via the ADSCR register. The ADC supports external voltage references on VREFH and VREFL pins, enabling precise measurement ranges independent of supply voltage - critical for accurate sensor interfacing in variable-voltage industrial environments.

What low-power modes are available on the MC68HC908GT16CB?

The MC68HC908GT16CB provides two hardware-supported low-power modes: Wait mode (CPU halted, peripherals active) and Stop mode (all clocks stopped except LVI and reset logic). In Wait mode, the ICG remains operational, allowing fast wake-up (<1 µs) via IRQ, KBI, or ESCI activity. In Stop mode, current consumption drops to ~1 µA, with wake-up possible only via RST, IRQ, or KBI - making it suitable for battery-powered sensor nodes requiring multi-week standby duration.

Is the MC68HC908GT16CB pin-compatible with other HCS08 family members?

No, the MC68HC908GT16CB is not pin-compatible with other HCS08 devices such as MC9S08QG8 or MC9RS08KA8 due to differences in package (40-pin SOIC vs. 20-pin TSSOP/SOIC), I/O mapping, and peripheral signal assignment. While functional overlap exists in core architecture and register layout, physical pinout, power pin placement, and peripheral multiplexing differ significantly - requiring PCB redesign for substitution. Always verify pin assignments against the specific device's datasheet before migration.