NXP Semiconductors MC68HC908QT4CP

Overview

MC68HC908QT4CP from Freescale Semiconductor 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 (4 MHz nominal), low-voltage inhibit (LVI), computer operating properly (COP) watchdog, and keyboard interrupt (KBI) module. Designed for cost-sensitive embedded control in appliance motor interfaces and industrial sensor nodes.

For engineers reviewing the MC68HC908QT4CP datasheet, MC68HC908QT4CP pinout, MC68HC908QT4CP application, or MC68HC908QT4CP equivalent, key selection criteria include its 8-pin SOIC package, 4 MHz internal clock accuracy (±5% over temperature), 8-bit ADC resolution with 10 µs conversion time, and support for WAIT/STOP low-power modes with wake-up via IRQ or KBI.

Technical Context

The MC68HC908QT4CP implements the M68HC08 CPU core with 16-bit address bus and Harvard architecture. Its memory map includes 4 KB FLASH (user-programmable, block-erasable), 192 B RAM, and 128 B EEPROM-equivalent data storage via FLASH emulation.

Peripherals include a 16-bit Timer Interface Module (TIM) with input capture/output compare, 8-bit ADC with selectable reference (VDD or internal bandgap), Auto Wake-Up (AWU) timer, and dual-interrupt-capable I/O ports (Port A and Port B). All modules are managed through the System Integration Module (SIM).

Key Specifications

Pinout & Package

MC68HC908QT4CP is housed in an 8-pin SOIC package (case #751A-02) with 1.27 mm pitch. Pin functions are defined per shared-resource priority in Table 1-3 of the family datasheet.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with MC68HC908QT2CP and MC9RS08KA2CP, the MC68HC908QT4CP offers 2× more FLASH for bootloader support or feature-rich firmware, retains KBI for keypad-based wake-up, and delivers deterministic LVI reset behavior critical in mains-powered appliances.

Availability

MC68HC908QT4CP is available at Aetrix Electronics and suitable for home appliance control, industrial sensor node, and motor drive interface applications requiring stable component supply and long-term industrial temperature support.

Supply support for MC68HC908QT4CP 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) designed high-reliability microcontrollers for automotive, industrial, and consumer markets before its 2015 acquisition.

The MC68HC908QY/QT family was engineered for cost-optimized 8-bit control in space-constrained, low-power embedded systems-emphasizing integrated analog peripherals, robust reset architecture, and minimal external component count.

FAQ

What is the maximum operating frequency of the MC68HC908QT4CP?

The MC68HC908QT4CP operates with a maximum bus clock frequency of 4 MHz, derived from its factory-trimmed internal RC oscillator. This frequency is fixed and not user-adjustable; external crystal or capacitor-based oscillator configurations are supported but do not increase the maximum rated bus speed beyond 4 MHz. The MC68HC908QT4CP does not support PLL multiplication or frequency synthesis.

Does the MC68HC908QT4CP support in-circuit programming?

Yes, the MC68HC908QT4CP supports in-circuit programming via the Background Debug Mode (BDM) interface using a standard Freescale BDM pod. Programming requires the MC68HC908QT4CP to be in monitor mode, accessed through the BKGD pin (shared with PTA2 in some variants-but not on the QT4CP 8-pin SOIC, which uses dedicated BDM pinout per datasheet Figure 1-2). Firmware updates can be performed without removing the MC68HC908QT4CP from the target PCB.

How many ADC channels does the MC68HC908QT4CP have, and what is their resolution?

The MC68HC908QT4CP integrates an 8-bit successive-approximation ADC with eight input channels (AD0–AD7), though only AD0 and AD1 are routed to physical pins (PTB0 and PTB1) in the 8-pin SOIC package. Resolution is strictly 8 bits (256 levels), with integral nonlinearity (INL) of ±1 LSB and differential nonlinearity (DNL) of ±1 LSB, as specified in Section 3.5.5 of the family datasheet. Conversion time is 10 µs at 4 MHz bus clock.

Can the MC68HC908QT4CP operate from a 3.3 V supply?

Yes, the MC68HC908QT4CP supports operation from 2.7 V to 5.5 V, making 3.3 V fully compliant. At 3.3 V, the internal RC oscillator maintains 4 MHz ±5% accuracy across –40°C to +85°C, and all I/O pins remain 5 V-tolerant. However, the LVI reset threshold remains fixed at 2.5 V ±0.1 V, so brown-out detection still functions correctly, asserting reset if supply drops below that level-even when powered from 3.3 V.

Is there hardware support for wake-up from STOP mode on the MC68HC908QT4CP?

Yes, the MC68HC908QT4CP provides two dedicated hardware wake-up sources from STOP mode: the External Interrupt (IRQ) input on PTA0 and the Keyboard Interrupt (KBI) inputs on PTA1 and PTA2. Both trigger immediate exit from STOP mode and vector to respective interrupt service routines. No polling or clocked activity is required-the MC68HC908QT4CP resumes execution from the instruction following STOP within six bus cycles after wake-up assertion.