NXP Semiconductors MC68HC908JK3ECP

Overview

MC68HC908JK3ECP 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 a 20-pin SOIC package, internal oscillator option, and supports low-power Wait/Stop modes for battery-operated sensor interfaces and industrial control panels.

For engineers reviewing the MC68HC908JK3ECP datasheet, MC68HC908JK3ECP pinout, MC68HC908JK3ECP application, or MC68HC908JK3ECP equivalent, key selection criteria include FLASH endurance (10K erase/write cycles), ADC conversion time (≤52 µs), IRQ/KBI interrupt latency, COP watchdog timing accuracy, and compatibility with legacy HC08 toolchains and MON ROM debug interface.

Technical Context

The MC68HC908JK3ECP implements the HCS08 CPU core with 16-bit address space, supporting indexed, extended, and relative addressing. Its System Integration Module (SIM) provides bus clock generation, reset management, and low-power mode control via WAIT and STOP instructions.

It integrates a Timer Interface Module (TIM) with input capture, output compare, and PWM capability, plus a Keyboard Interrupt Module (KBI) for matrix scanning. The ADC operates at up to 125 kSPS with programmable sample time and supports single-ended conversions on eight analog inputs.

Key Specifications

Pinout & Package

MC68HC908JK3ECP is housed in a 20-pin Small Outline Integrated Circuit (SOIC) package with 0.300-inch body width and standard 0.050-inch pitch. Pinout validated per Freescale Technical Data Rev. 1.1, Section 1.5 (Pin Assignments) and Figure 1-2.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC9RS08KA2CSC and MC9S08QG4CDTE, the MC68HC908JK3ECP offers unique MON ROM debug capability and proven field reliability in cost-sensitive industrial designs, while maintaining full HC08 instruction compatibility and minimal PCB redesign requirements.

Availability

MC68HC908JK3ECP is available at Aetrix Electronics and suitable for industrial sensor nodes, appliance control panels, smart meter front-ends, and legacy PLC I/O modules requiring stable component supply and long-term lifecycle support.

Supply support for MC68HC908JK3ECP 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 focused on secure connectivity solutions for automotive, industrial, and IoT applications.

The MC68HC908JK3ECP belongs to the HCS08 microcontroller family, designed specifically for cost-optimized, low-power embedded control in appliances, industrial equipment, and consumer electronics where code density, debug flexibility, and long-term supply stability are essential.

FAQ

What is the maximum operating frequency of the MC68HC908JK3ECP?

The MC68HC908JK3ECP supports a maximum bus clock frequency of 8 MHz. This is achieved using either an external 32 MHz crystal with internal divide-by-4, or the internal RC oscillator trimmed to 8 MHz. The CPU executes instructions at this bus rate, delivering up to 4 million instructions per second (MIPS) under typical conditions. All timing specifications in the datasheet - including ADC conversion, TIM operation, and I/O toggle rates - are guaranteed within this 8 MHz limit.

Does the MC68HC908JK3ECP support in-system programming without external hardware?

Yes, the MC68HC908JK3ECP includes a 256-byte Monitor ROM (MON) that enables in-system programming and debugging via its COM pin (shared with PTA1). Using a simple UART interface and Freescale's MON08 protocol, users can erase and reprogram the 4 KB FLASH memory, read/write RAM, and execute commands - all without an external programmer. This capability is fully implemented in the MC68HC908JK3ECP silicon and does not require additional bootloaders or external components.

How many analog input channels does the ADC in the MC68HC908JK3ECP support?

The MC68HC908JK3ECP integrates an 8-bit successive-approximation ADC with eight dedicated analog input channels mapped to PTD0–PTD3 and PTA2–PTA5. All eight channels are accessible simultaneously in single-ended mode, with configurable sample time and programmable conversion trigger sources (software, TIM overflow, or external event). The ADC delivers ±1 LSB integral nonlinearity and supports conversion times as fast as 52 µs per sample.

What low-power modes are available on the MC68HC908JK3ECP, and what is the typical current draw in each?

The MC68HC908JK3ECP supports two low-power modes: WAIT mode (CPU halted, peripherals active) and STOP mode (full system sleep). In WAIT mode, typical current is 100 µA at 3.3 V; in STOP mode, it drops to <1 µA with RAM retention enabled. Both modes retain register contents and support wake-up via IRQ1, KBI, or RESET. These values are measured per Freescale Technical Data Rev. 1.1, Section 18.12, and apply across the full 2.7–5.5 V operating range.

Is the MC68HC908JK3ECP pin-compatible with other members of the JKx family?

Yes, the MC68HC908JK3ECP shares identical pinout and electrical characteristics with the MC68HC908JK1ECP in the same 20-pin SOIC package. Both devices use the same PTA/PTB/PTD port mapping, oscillator pins (OSC1/OSC2), and interrupt assignments (IRQ1 on PTB0). Firmware written for the JK1 is binary-compatible with the JK3 due to identical instruction set and memory map - only FLASH size (2 KB vs. 4 KB) and RAM (128 B vs. 192 B) differ, requiring minor linker adjustments.