NXP Semiconductors MC68HC705C9AFNE

Overview

MC68HC705C9AFNE from Freescale Semiconductor is a 8-bit HCMOS EPROM-based microcontroller in the M68HC05 family, featuring 15,932 bytes of user EPROM, 352 bytes of RAM, a 16-bit capture/compare timer, asynchronous SCI and synchronous SPI interfaces, and COP watchdog with clock monitor. It operates from 3.0 V to 5.5 V and supports wait/stop low-power modes for embedded control in industrial sensors and appliance motor controllers.

For engineers reviewing the MC68HC705C9AFNE datasheet, MC68HC705C9AFNE pinout, MC68HC705C9AFNE application, or MC68HC705C9AFNE equivalent, key selection criteria include EPROM programmability, dual-configuration capability (C9A/C12A), I/O flexibility (31 bidirectional lines), on-chip oscillator support, and security features for firmware protection.

Technical Context

The MC68HC705C9AFNE implements the M68HC05 CPU core with accumulator, index register, stack pointer, and condition code register. Its memory map is software-configurable to emulate either MC68HC05C9A (full 16 KB address space) or MC68HC05C12A (reduced map), controlled via mask option registers (PBMOR at $3FF0, C12MOR at $3FF1) and software-accessible control registers.

It integrates three serial peripherals: SCI for UART-style full-duplex communication, SPI for synchronous master/slave data exchange, and a 16-bit timer supporting input capture (event timing) and output compare (PWM generation). The COP watchdog uses an independent clock monitor to detect oscillator failure and trigger reset.

Key Specifications

Pinout & Package

MC68HC705C9AFNE is housed in a 44-lead Plastic Leaded Chip Carrier (PLCC) package (Case 777-02), with 44 solderable gull-wing leads and a 16.5 mm × 16.5 mm body size. Pin 1 is marked by a corner notch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC705C9AFNE, the MC68HC705P6ACD offers lower cost and smaller footprint but lacks SPI and advanced timer features, while the MC68HC908QT4CD provides FLASH-based upgradability and modern peripherals at the expense of direct replacement compatibility.

Availability

MC68HC705C9AFNE is available at Aetrix Electronics and suitable for industrial automation, appliance control, and legacy equipment repair requiring stable component supply and long-term obsolescence management.

Supply support for MC68HC705C9AFNE 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) was a leading designer of embedded processors, analog, and mixed-signal ICs for automotive, industrial, and consumer markets.

The MC68HC705C9AFNE belongs to the M68HC05 microcontroller family, designed for cost-sensitive, low-power embedded control applications where EPROM-based firmware persistence and simple peripheral integration were prioritized over flash reprogrammability.

FAQ

What is the maximum operating frequency of the MC68HC705C9AFNE?

The MC68HC705C9AFNE supports a maximum crystal frequency of 4.9152 MHz, yielding a 2.4576 MHz internal bus clock (via on-chip divide-by-two). This frequency is validated across the full industrial temperature range (–40°C to +85°C) and 3.0–5.5 V supply, enabling deterministic timing for SCI baud rates up to 115.2 kbps and precise 16-bit timer resolution.

Does the MC68HC705C9AFNE support in-circuit programming?

No, the MC68HC705C9AFNE does not support in-circuit programming. It requires parallel EPROM programming using a dedicated programmer before soldering. Programming occurs via VPP (12.5 V) applied to pin 1 during device programming mode, and firmware is locked via EPROM security bits to prevent readout - making field updates impractical without physical chip replacement.

How is the MC68HC705C9AFNE configured to operate as an MC68HC05C12A?

The MC68HC705C9AFNE is configured as an MC68HC05C12A by programming the C12MOR ($3FF1) to enable C12A options and disabling the C9A option register ($3FDF). This disables dual-mapped RAM/EPROM regions ($0100–$0FFF), restricts I/O to 24 bidirectional + 6 input-only lines, and activates the C12 COP clear register ($3FF0) while deactivating C9A COP control registers.

What are the voltage-level requirements for the MC68HC705C9AFNE's I/O pins?

The MC68HC705C9AFNE I/O pins are fully 5 V-tolerant when powered from 5.0 V, and operate down to 3.0 V supply. Input thresholds are TTL-compatible (VIH ≥ 2.0 V, VIL ≤ 0.8 V) across the full supply range. Port C pin PC7 supports 20 mA sink and 5 mA source capability, enabling direct LED driving or relay coil control without external buffers.

Can the MC68HC705C9AFNE's SPI interface operate as a slave device?

Yes, the MC68HC705C9AFNE's SPI interface supports both master and slave operation. In slave mode, it responds to clock and chip-select signals from an external master, with data exchanged via PD2 (MISO), PD3 (MOSI), PD4 (SCK), and PD5 (SS). The SPI status register (SPSR) and data I/O register (SPDR) enable full-duplex byte transfers synchronized to the incoming SCK edge.