NXP Semiconductors MCHRC705KJ1CPE

Overview

MCHRC705KJ1 from NXP Semiconductors (formerly Freescale) is a 8-bit HCMOS microcontroller based on the M68HC05 core, featuring 1240 Bytes of OTPROM, 64 Bytes RAM, a 15-stage multifunction timer, and COP watchdog. It operates at up to 4.0 MHz at 5.0 V and supports crystal, ceramic resonator, RC oscillator, or external clock inputs. Used in cost-sensitive embedded control applications such as appliance timers and industrial sensor interfaces.

For engineers reviewing the MCHRC705KJ1 datasheet, MCHRC705KJ1 pinout, MCHRC705KJ1 application, or MCHRC705KJ1 equivalent, key selection criteria include its OTPROM size, 10 I/O lines with 10-mA sink capability, RC oscillator option, selectable interrupt sensitivity, and low-power stop/wait modes - all critical for battery-powered or noise-immune control designs.

Technical Context

The MCHRC705KJ1 implements the M68HC05 CPU core with fully static operation, no minimum clock speed requirement, and memory-mapped I/O. Its oscillator supports RC configuration (with or without external resistor), enabling flexible clock generation without crystals in space-constrained designs.

Peripheral integration includes a 15-stage timer with real-time and overflow interrupts, a configurable COP watchdog with timeout period selection, and dual-port parallel I/O (Port A and Port B) with software-programmable pulldowns, keyboard-scan interrupt on four pins, and mixed drive strength (5.5 mA source on six pins, 10 mA sink on all ten).

Key Specifications

Pinout & Package

Package: 16-pin PDIP (Case #648), 16-pin SOIC (Case #751G), or 16-pin CERDIP (Case #620A). Pinout validated per Freescale MC68HC705KJ1 Rev. 4.1 datasheet Figures 1-2 and 1-4–1-8.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCHRC705KJ1, the MC68HC705KJ1 lacks RC oscillator flexibility but offers better frequency accuracy, while the MC68HLC705KJ1 trades drive strength and voltage range for extreme low-power operation - making each variant optimal for distinct power, cost, and timing budgets.

Availability

MCHRC705KJ1 is available at Aetrix Electronics and suitable for appliance timer control, industrial sensor interface, smart power outlet management, and legacy equipment retrofit requiring stable component supply and long-term obsolescence support.

Supply support for MCHRC705KJ1 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 solutions and embedded processing.

The MCHRC705KJ1 belongs to the legacy M68HC05 microcontroller family, designed for cost-effective, low-complexity embedded control in consumer, industrial, and automotive subsystems where deterministic real-time behavior and OTP firmware security are essential.

FAQ

What is the primary oscillator configuration supported by the MCHRC705KJ1?

The MCHRC705KJ1 is specifically configured with an RC oscillator option, allowing operation without external crystals or resonators. This variant uses an internal resistor-capacitor network for clock generation, supporting frequencies up to 4.0 MHz at 5.0 V. The RC oscillator can be used with or without an external resistor, offering design flexibility in cost- and space-constrained applications. The MCHRC705KJ1 datasheet confirms this configuration in Appendix A and Section 1.4.2.3.

Does the MCHRC705KJ1 support in-circuit programming after soldering?

No, the MCHRC705KJ1 uses OTPROM (one-time programmable read-only memory), which must be programmed before final assembly using a dedicated EPROM programmer applying 12.5 V to the IRQ/VPP pin. Once programmed, the firmware cannot be rewritten. The MCHRC705KJ1 does not support ISP or in-system reprogramming; firmware updates require physical device replacement. This is confirmed in Section 2.7 and Figure 1-2 of the Freescale datasheet.

What are the low-power modes available on the MCHRC705KJ1 and their typical current draw?

The MCHRC705KJ1 supports Stop, Wait, and Data-Retention modes. In Stop mode, current drops below 10 µA (typical) with CPU, clocks, and most peripherals halted; RAM contents are retained. Wait mode disables the CPU only, maintaining peripheral clocks and allowing faster wake-up. Data-Retention mode preserves RAM with minimal current while disabling all other functions. These values are specified in Chapter 6 and Table 10-8 of the MCHRC705KJ1 datasheet.

Can the MCHRC705KJ1 drive LEDs directly without external transistors?

Yes, the MCHRC705KJ1 can drive LEDs directly: all 10 I/O pins provide 10-mA sink capability, and six pins (PA0–PA5) offer 5.5-mA source capability. This allows common-cathode LED connections (sink mode) with series resistors calculated for VDD = 5.0 V. The MCHRC705KJ1's Port A LED drive capability is explicitly documented in Section 7.2.4 and Table 10-7 of the datasheet.

Is the MCHRC705KJ1 pin-compatible with other variants in the MC68HC705KJ1 family?

Yes, the MCHRC705KJ1 shares identical pinout, memory map, and I/O register structure with MC68HC705KJ1 and MC68HLC705KJ1, as confirmed in Figures 1-2 and 11-1–11-3 of the datasheet. All variants use the same 16-pin PDIP/SOIC/CERDIP packages and maintain register-level compatibility, enabling hardware reuse across oscillator variants - though firmware may require minor clock initialization adjustments.