NXP Semiconductors MC68HC908QT4CPE

Overview

MC68HC908QT4CPE from NXP (formerly Freescale) is an 8-bit HCS08-core microcontroller with 4 KB on-chip FLASH, 192 B RAM, and integrated 8-channel 8-bit ADC. It features internal RC oscillator (1–8 MHz), low-voltage inhibit (LVI), computer operating properly (COP) watchdog, and keyboard interrupt (KBI) for touch-key applications. Used in cost-sensitive industrial control panels and appliance user interfaces.

For engineers reviewing the MC68HC908QT4CPE datasheet, MC68HC908QT4CPE pinout, MC68HC908QT4CPE application, or MC68HC908QT4CPE equivalent, key selection criteria include its 16-pin SOIC-16W package, 5 V operation, internal oscillator trim capability, and support for WAIT/STOP low-power modes - critical for battery-operated front-panel controllers.

Technical Context

The MC68HC908QT4CPE implements the M68HC08 CPU core with 16-bit address bus and Harvard architecture. It executes instructions at up to 8 MHz bus clock (via internal RC oscillator or external crystal), supports single-cycle 8-bit arithmetic, and includes a 16-bit timer interface module (TIM) with input capture, output compare, and PWM generation.

Its system integration module (SIM) provides reset control, clock gating, and interrupt vector management. The device integrates a 3-level priority interrupt system supporting IRQ, KBI, ADC conversion complete, and TIM overflow - all configurable via dedicated status and control registers mapped in the $FF00–$FFFF I/O space.

Key Specifications

Pinout & Package

MC68HC908QT4CPE is housed in a 16-pin SOIC wide-body (SOIC-16W) package with 0.300-inch body width and 1.27 mm pitch. Pin assignments are defined per Figure 1-2 and Table 1-2 of the MC68HC908QY/QT Family Data Sheet, Rev. 6.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC908QT2CPE and MC9RS08KA2CPE, the MC68HC908QT4CPE uniquely balances 4 KB programmable FLASH, hardware KBI, and 8-channel 8-bit ADC in a 16-pin SOIC - making it optimal for cost-constrained, touch-enabled control applications where code growth headroom and analog integration are essential.

Availability

MC68HC908QT4CPE is available at Aetrix Electronics and suitable for industrial control panels, home appliance user interfaces, and smart power outlets requiring stable component supply and long-term manufacturing continuity.

Supply support for MC68HC908QT4CPE 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 company formed from the spin-off of Philips' semiconductor division, now specializing in secure connectivity and embedded processing solutions.

The MC68HC908QT4CPE belongs to the legacy HCS08 microcontroller family, designed for cost-effective, low-pin-count embedded control in appliances, industrial equipment, and consumer electronics where reliability and toolchain maturity are critical.

FAQ

What is the maximum operating frequency of the MC68HC908QT4CPE?

The MC68HC908QT4CPE supports a maximum bus clock frequency of 8 MHz, achievable using its factory-trimmed internal RC oscillator. External crystal or ceramic resonator configurations can also operate up to 8 MHz. This frequency determines instruction execution speed and peripheral timing - for example, the ADC completes conversions in ≤25 µs at 8 MHz bus clock, enabling up to 40 kSPS sampling in burst mode. The MC68HC908QT4CPE does not support PLL multiplication or higher-frequency modes.

Does the MC68HC908QT4CPE include a hardware watchdog timer?

Yes, the MC68HC908QT4CPE includes a Computer Operating Properly (COP) watchdog module. It is configured via the COPCTL register and offers selectable timeout periods (0.5 ms to 1.0 s) based on bus clock prescaling. The COP must be periodically cleared by firmware; failure to do so triggers a hardware reset. This feature is enabled by default after reset and is critical for fail-safe operation in unattended systems like appliance controllers. The MC68HC908QT4CPE COP operates independently of CPU sleep modes.

Can the MC68HC908QT4CPE operate from a 3.3 V supply?

No, the MC68HC908QT4CPE is specified only for 4.5 V to 5.5 V operation per its electrical characteristics in Chapter 16 of the datasheet. It lacks 3.3 V I/O tolerance or internal voltage regulation. Attempting 3.3 V operation will result in undefined behavior, including failed FLASH programming, unreliable ADC readings, and intermittent resets. For 3.3 V designs, consider modern NXP S08 or Kinetis families - the MC68HC908QT4CPE requires strict adherence to its 5 V supply specification.

How many analog input channels does the ADC in the MC68HC908QT4CPE support?

The MC68HC908QT4CPE integrates an 8-channel 8-bit successive approximation ADC. Channels AN0–AN3 map to PTA0–PTA3, while AN4–AN7 are routed to PTB0, PTB1, and two additional pins shared with Port A (per Table 1-2 and Section 3.3.1). All eight channels are software-selectable via the ADC Input Channel Select bits in the ADC Status and Control Register (ADSC). The ADC supports single-ended conversion only and requires external decoupling on the VRL/VREF pins for accuracy.

Is the MC68HC908QT4CPE pin-compatible with other devices in the QY/QT family?

Yes, the MC68HC908QT4CPE shares identical pinout and package (SOIC-16W) with MC68HC908QT2CPE and MC68HC908QT1CPE, enabling direct substitution within the QT subfamily. However, it is not pin-compatible with QY-series variants (e.g., MC68HC908QY4CPE), which use a different 20-pin SOIC package and expanded peripheral set. Firmware compatibility depends on resource usage - the MC68HC908QT4CPE's 4 KB FLASH and 192 B RAM exceed QT2/QT1, allowing upward migration without hardware change.