NXP Semiconductors MC68HC908LK24CPK

Overview

MC68HC908LK24CPK from Freescale Semiconductor is an 8-bit HCS08-core microcontroller with 24 KB on-chip FLASH, 512 B RAM, integrated RTC, LCD driver (up to 32 segments), and IRSCI interface. It operates at up to 8 MHz bus frequency, supports low-power stop/wait modes, and targets embedded control in industrial panels and consumer appliances requiring real-time timekeeping and display.

For engineers reviewing the MC68HC908LK24CPK datasheet, MC68HC908LK24CPK pinout, MC68HC908LK24CPK application, or MC68HC908LK24CPK equivalent, key selection criteria include its 64-pin LQFP package, integrated RTC calibration register (RTCCOMR), LCD bias voltage (VLCD) support, and SuperFlash® technology enabling 100K write/erase cycles - critical for firmware-updatable metering and appliance HMI designs.

Technical Context

The MC68HC908LK24CPK implements the HCS08 CPU core with a 16-bit address bus, supporting indexed, extended, and relative addressing. Its Clock Generator Module (CGM) integrates a PLL with programmable multiplier (×1 to ×32) and reference divider, enabling precise bus clock derivation from internal RC or external crystal sources.

System integration includes a System Integration Module (SIM) managing reset sources (POR, LVI, COP), interrupt prioritization across 16 vectors, and power management with stop mode current <1 µA. The Real Time Clock (RTC) provides calendar, alarm, chronograph, and temperature-compensated timebase functions via dedicated registers including RTCCDAT and RTCCR1.

Key Specifications

Pinout & Package

MC68HC908LK24CPK is housed in a 64-pin LQFP (7 mm × 7 mm, 0.5 mm pitch) package with exposed thermal pad. Pin assignments are defined per Section 1.5 (Pin Assignments) and Section 1.6 (Pin Functions) of the Rev. 2.1 datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC908LK24CPK, the LJ24 variant removes RTC and LCD functions while retaining identical packaging and FLASH/RAM - making it a streamlined alternative for simpler control tasks. The RS08KA2 offers smaller memory and no timekeeping, but achieves lower active current (120 µA/MHz) at the expense of peripheral integration.

Availability

MC68HC908LK24CPK is available at Aetrix Electronics and suitable for industrial control panels, smart appliance HMIs, energy meter displays, and portable medical timers requiring stable component supply and long-term manufacturability.

Supply support for MC68HC908LK24CPK 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) is a fabless semiconductor company specializing in embedded processing, analog, and connectivity solutions for automotive, industrial, and consumer markets.

The MC68HC908LK24CPK belongs to the HC08 family, designed specifically for cost-sensitive, low-power embedded applications requiring integrated peripherals like RTC, LCD, and IR communication - targeting appliance, metering, and human-interface markets.

FAQ

What is the maximum operating frequency of the MC68HC908LK24CPK?

The MC68HC908LK24CPK supports a maximum bus frequency of 8 MHz, achieved via its integrated Clock Generator Module (CGM) PLL. This frequency is derived from either the internal RC oscillator or an external crystal (1–8 MHz), with the PLL providing multiplication factors from ×1 to ×32. The actual core instruction throughput depends on bus speed and instruction cycle count, with most instructions executing in 1–3 bus cycles.

Does the MC68HC908LK24CPK support in-system programming (ISP)?

Yes, the MC68HC908LK24CPK supports in-system programming via its Monitor ROM (MON) using the IRSCI interface. The MON provides bootloader routines (e.g., PRGRNGE, ERARNGE) accessible through a serial command protocol at configurable baud rates. Programming requires no external programmer - only a UART-to-IR adapter or direct SCI connection, and the device remains soldered on the target board during firmware updates.

How does the RTC calibration work on the MC68HC908LK24CPK?

The MC68HC908LK24CPK RTC calibration uses the RTCCOMR register to adjust the 32.768 kHz oscillator's effective period by ±127 ppm in 1 ppm steps. Calibration data is stored in the RTCCDAT register and applied automatically during RTC initialization. This allows compensation for crystal tolerance and temperature drift, achieving ±2 ppm typical accuracy after factory or field calibration - critical for metering and timestamping applications.

Can the MC68HC908LK24CPK drive a 4×32 segment LCD without external components?

Yes, the MC68HC908LK24CPK integrates a full LCD driver capable of directly driving up to 4 commons and 32 segments (128 segments total) using its VLCD pin to generate the required bias voltage. No external resistors, capacitors, or charge pumps are needed for standard 3V or 5V LCD modules, significantly simplifying the display interface and reducing bill-of-materials cost compared to MCUs requiring external LCD drivers.

What low-power modes are supported by the MC68HC908LK24CPK?

The MC68HC908LK24CPK supports Wait Mode (CPU halted, peripherals active, RAM retained) and Stop Mode (all clocks stopped, RAM retention optional, RTC continues running). In Stop Mode, typical current consumption is <1 µA with RTC enabled, making it suitable for battery-powered devices requiring multi-year operation. Wakeup is possible via IRQ, RTC alarm, or KBI events - all configurable in the SIM and RTC registers.