NXP Semiconductors MCHC705KJ1CDWE

Overview

MCHC705KJ1CDWE from Freescale Semiconductor is a 8-bit HCMOS microcontroller based on the M68HC05 core, featuring 1240 Bytes of EPROM/OTPROM, 64 Bytes of RAM, a 15-stage multifunction timer, and COP watchdog. It operates at up to 4.0 MHz (5.0 V), supports crystal/RC/ceramic resonator oscillators, and delivers 10-mA sink capability on all 10 I/O pins - used in embedded control systems such as appliance motor controllers and industrial sensor interfaces.

For engineers reviewing the MCHC705KJ1CDWE datasheet, MCHC705KJ1CDWE pinout, MCHC705KJ1CDWE application, or MCHC705KJ1CDWE equivalent, key selection criteria include OTPROM size, 10-pin I/O count with keyboard scan interrupt support, COP watchdog timeout configurability, and compatibility with 5.0-V or 3.3-V supply rails in low-power stop/wait modes.

Technical Context

The MCHC705KJ1CDWE implements the M68HC05 CPU core with fully static operation, no minimum clock speed requirement, and memory-mapped I/O registers. Its 15-stage timer supports real-time interrupt and overflow functions, while the COP module provides configurable watchdog timeout periods via internal prescaler settings.

It integrates programmable oscillator options (crystal, ceramic resonator, RC network, or external clock), selectable edge/level-sensitive IRQ triggering, software-controllable pulldown resistors on all I/O pins, and EPROM security bit for code protection - all managed through the mask option register (MOR) and dedicated control registers.

Key Specifications

Pinout & Package

Package: 16-pin SOIC (Case #751G), surface-mount, 300 mil width.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC705P6CDWE and MC9RS08KA2CP, the MCHC705KJ1CDWE offers proven OTPROM reliability for cost-sensitive fixed-function designs, simpler COP configuration, and direct 10-mA I/O drive without external buffers - making it optimal for high-volume, unchanging-control applications where Flash flexibility or SPI are unnecessary.

Availability

MCHC705KJ1CDWE is available at Aetrix Electronics and suitable for home appliance control, industrial sensor interface, consumer remote control, and medical device monitor applications requiring stable component supply across multi-year production cycles.

Supply support for MCHC705KJ1CDWE 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) pioneered 8-bit microcontroller architectures for automotive and industrial markets, emphasizing robustness, noise immunity, and mixed-signal integration.

The M68HC05 family - including the MCHC705KJ1CDWE - was designed for cost-effective, low-pin-count embedded control in appliances, instrumentation, and safety-critical subsystems where OTPROM security and deterministic timing are essential.

FAQ

What is the maximum operating frequency of the MCHC705KJ1CDWE?

The MCHC705KJ1CDWE operates at a maximum internal frequency of 4.0 MHz when powered at 5.0 V DC. Its fully static design permits operation down to 0 Hz (halted state), enabling ultra-low-power wait and stop modes without clock stability concerns. This specification is confirmed in Section 1.1 Features and Electrical Specifications Chapter 10 of the official Freescale datasheet Rev. 4.1.

Does the MCHC705KJ1CDWE support in-circuit programming or debugging?

No, the MCHC705KJ1CDWE uses OTPROM (one-time programmable read-only memory) and lacks on-chip debug interfaces like BDM or SWD. Programming requires 12.5 V applied to the IRQ/VPP pin in a dedicated programmer fixture, and code cannot be modified post-deployment. This is documented in Sections 2.7 and 10.9 of the Freescale MC68HC705KJ1 datasheet Rev. 4.1.

How does the COP watchdog function on the MCHC705KJ1CDWE?

The COP (Computer Operating Properly) watchdog on the MCHC705KJ1CDWE is a configurable timer that resets the MCU if not cleared within its timeout period. Timeout duration is set via the mask option register (MOR) and remains active in wait mode but is disabled in stop mode. Its behavior is detailed in Chapter 3 of the Freescale datasheet Rev. 4.1, confirming its role as a hardware-level safety mechanism against firmware lockups.

Can the MCHC705KJ1CDWE operate from a 3.3-V supply?

Yes, the MCHC705KJ1CDWE supports dual supply operation: 5.0 V ±10% (standard) and 3.3 V ±10% (low-voltage variant). Electrical characteristics for both rails are specified separately in Chapter 10 of the Freescale datasheet Rev. 4.1, including reduced max frequency (2.0 MHz at 3.3 V) and adjusted I/O drive strength. This enables interoperability with modern low-voltage peripherals.

What oscillator options are supported by the MCHC705KJ1CDWE?

The MCHC705KJ1CDWE supports four oscillator configurations: external crystal (1–4 MHz), ceramic resonator, RC network (with or without external resistor), and external clock input. The oscillator type is selected via external component connections and internal MOR bits. Details appear in Section 1.4.2 and Appendix A/B of the Freescale MC68HC705KJ1 datasheet Rev. 4.1.