NXP Semiconductors MCHC705JJ7CPE

Overview

MCHC705JJ7CPE from Freescale Semiconductor is a 8-bit HCMOS microcontroller featuring 4 KB on-chip EPROM, 128 bytes RAM, and integrated analog subsystem including dual voltage comparators, 8-channel 8-bit ADC, and internal temperature sensor. It operates at up to 4 MHz with 5 V supply and supports multiple low-power modes (Stop, Wait, Halt, Data-Retention). Used in cost-sensitive embedded control applications such as appliance motor control and industrial sensor interfaces.

For engineers reviewing the MCHC705JJ7CPE datasheet, MCHC705JJ7CPE pinout, MCHC705JJ7CPE application, or MCHC705JJ7CPE equivalent, key selection criteria include its OTP EPROM programmability, SIOP serial interface, COP watchdog timer, and PB port's dual-role analog/digital I/O capability - all critical for legacy automotive body electronics and retrofit control modules.

Technical Context

The MCHC705JJ7CPE implements the M68HC05 CPU core with 41 instruction mnemonics, 8-bit data bus, and Harvard-style memory architecture separating program and data spaces. Its interrupt system supports 11 vectors including IRQ/VPP external interrupt, core timer overflow, and analog comparator match events.

It integrates a 16-bit programmable timer with input capture and output compare functions, a simple synchronous serial interface (SIOP) compatible with SPI-like protocols, and an analog subsystem supporting ratiometric and absolute voltage measurements using internal or external references.

Key Specifications

Pinout & Package

Package: 28-pin plastic DIP (Dual In-line Package), through-hole mounting, 0.6-inch width, standard 0.1-inch pin pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC705JP7CPE and MC68HC705SJ7CPE, the MCHC705JJ7CPE uniquely balances full PB port analog multiplexing, IRQ/VPP dual-use capability, and 28-pin DIP serviceability - making it optimal for repairable, field-programmable legacy control units.

Availability

MCHC705JJ7CPE is available at Aetrix Electronics and suitable for appliance motor control, industrial temperature monitoring, automotive body electronics, and legacy PLC I/O expansion requiring stable component supply and long-term obsolescence management.

Supply support for MCHC705JJ7CPE 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, mixed-signal integration, and long-lifecycle support.

The M68HC05 family - including MCHC705JJ7CPE - was designed for cost-sensitive, reliability-critical embedded control where OTP programmability, analog integration, and low-power operation outweigh processing performance needs.

FAQ

What is the maximum operating frequency of the MCHC705JJ7CPE?

The MCHC705JJ7CPE operates at a maximum system clock frequency of 4 MHz when driven by an external crystal or ceramic resonator connected to OSC1/OSC2. This corresponds to a 1 µs instruction cycle time for most instructions. The device does not support internal RC oscillation or higher-frequency modes - exceeding 4 MHz violates AC timing specifications and may cause undefined behavior in the MCHC705JJ7CPE.

Does the MCHC705JJ7CPE support in-circuit programming after soldering?

No, the MCHC705JJ7CPE does not support in-circuit programming. EPROM programming requires applying 12.5 V to the IRQ/VPP pin while holding RESET low and executing a specific 6-byte sequence - a process only feasible in a dedicated programmer socket. Once programmed, the MCHC705JJ7CPE is one-time programmable; field updates require physical replacement of the MCHC705JJ7CPE.

Can the MCHC705JJ7CPE operate from a 3.3 V supply?

No, the MCHC705JJ7CPE is specified exclusively for 4.5–5.5 V operation. Its internal voltage regulator, COP watchdog threshold, and analog subsystem (including ADC reference and comparator hysteresis) are calibrated for 5 V nominal supply. Operation below 4.5 V risks brown-out resets, inaccurate ADC results, and unreliable SIOP communication - the MCHC705JJ7CPE is not 3.3 V tolerant.

How many analog input channels does the MCHC705JJ7CPE support?

The MCHC705JJ7CPE supports eight analog input channels (AN0–AN7), mapped to PB0–PB7 pins. These share pins with digital I/O and SIOP functions; configuration is controlled via the Analog Multiplex Register (AMUX). Channel selection, conversion trigger source (software, timer, or comparator), and reference mode (internal/external, absolute/ratiometric) are all software-configurable in the MCHC705JJ7CPE.

Is there hardware support for UART or CAN communication on the MCHC705JJ7CPE?

No, the MCHC705JJ7CPE does not include UART or CAN peripherals. It provides only the Simple Synchronous Serial Interface (SIOP), a 3-wire SPI-compatible interface (SCK/SDI/SDO) without framing or parity. Asynchronous serial communication requires bit-banged software UART implementation, and CAN protocol handling is outside the MCHC705JJ7CPE's hardware capability.