NXP Semiconductors MC68HC705C8AVFNE

Overview

MC68HC705C8AVFNE from Freescale Semiconductor is an 8-bit OTP microcontroller featuring 8 KB on-chip EPROM/OTPROM, 192 bytes RAM, a 16-bit capture/compare timer, SCI and SPI serial interfaces, and four 8-bit parallel I/O ports (PA–PD). It operates at up to 4 MHz internal bus speed with 5 V supply and supports low-power stop/wait modes. It targets embedded control in industrial sensors, motor drive logic, and legacy automotive subsystems.

For engineers reviewing the MC68HC705C8AVFNE datasheet, MC68HC705C8AVFNE pinout, MC68HC705C8AVFNE application, or MC68HC705C8AVFNE equivalent, this page delivers verified functional identity, package mapping, validated pin functions, real-world use cases, and two confirmed alternative parts for legacy design continuity and obsolescence mitigation.

Technical Context

The MC68HC705C8AVFNE implements the M68HC05 CPU core with accumulator-based architecture, supporting 7 addressing modes and 79 instructions. Its memory map includes 8 KB of one-time-programmable ROM, 192 B of RAM, and dedicated I/O register space mapped into the direct-page address range.

It integrates dual serial peripherals: an asynchronous SCI supporting full-duplex UART operation with programmable baud rate, and a synchronous SPI supporting master/slave configurations with configurable clock polarity and phase. The 16-bit timer provides input capture, output compare, and free-running count functionality with interrupt capability.

Key Specifications

Pinout & Package

MC68HC705C8AVFNE is housed in a 44-pin QFP (Quad Flat Pack) package per Case #824A, with 0.8 mm lead pitch and 10 mm × 10 mm body size. Pin assignments follow the standard 44-QFP layout defined in Section 1.6 and Figure 1-5 of the Rev. 3 datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC705C8AVFNE, MC68HC705P6ACD offers reduced memory and peripheral set for cost-sensitive minimal-control roles, while MC68HC705B16CFN extends capability with integrated A/D and doubled program storage - both retain identical 44-QFP mechanical compatibility but differ in feature depth and software migration effort.

Availability

MC68HC705C8AVFNE is available at Aetrix Electronics and suitable for industrial motor control, legacy automotive subsystems, appliance control units, and sensor interface modules requiring stable component supply and long-term obsolescence support.

Supply support for MC68HC705C8AVFNE 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 controllers, analog, and RF solutions for automotive, industrial, and networking markets.

The MC68HC705C8A belongs to the M68HC05 microcontroller family, engineered for cost-effective, low-pin-count embedded control in resource-constrained systems requiring OTP security and deterministic real-time response.

FAQ

What is the maximum operating frequency of the MC68HC705C8AVFNE?

The MC68HC705C8AVFNE supports a maximum internal bus frequency of 4 MHz, derived from its external crystal or resonator input. This corresponds to a 4 MHz system clock when using a 1:1 oscillator configuration. Timing specifications for all peripherals-including SCI baud generation, SPI transfers, and timer resolution-are defined relative to this bus clock, and operation beyond 4 MHz violates electrical specifications per Section 13.9 of the Rev. 3 datasheet.

Does the MC68HC705C8AVFNE support 3.3 V operation?

No, the MC68HC705C8AVFNE is specified exclusively for 5.0 V ±10% operation. Section 13.7 of the Rev. 3 datasheet lists DC electrical characteristics only for VDD = 5.0 V, and Section 13.8 explicitly states that 3.3 V parameters apply solely to the high-speed variant MC68HSC705C8A-not the standard MC68HC705C8A. Applying 3.3 V will result in undefined behavior, failed OTP programming, or unreliable reset operation.

How is OTP programming performed on the MC68HC705C8AVFNE?

OTP programming requires applying 12.5 V ±0.5 V to the VPP pin (Pin 1) while executing specific PROM programming routines from on-chip ROM, as detailed in Section 9.3 of the Rev. 3 datasheet. The process includes preprogramming steps, verify-after-write sequences, and optional security locking. Programming must occur before final system assembly, as the chip cannot be reprogrammed after initial write-no UV erasure or electrical rewrites are supported.

What serial communication protocols does the MC68HC705C8AVFNE support?

The MC68HC705C8AVFNE integrates two independent serial interfaces: an asynchronous Serial Communications Interface (SCI) compatible with standard UART protocols, and a synchronous Serial Peripheral Interface (SPI) supporting master or slave operation. Both include dedicated control/status registers, interrupt capability, and configurable timing-enabling robust host-to-peripheral or multi-drop sensor network communication without external protocol ICs.

Is the MC68HC705C8AVFNE pin-compatible with other MC68HC705 variants?

The MC68HC705C8AVFNE in 44-pin QFP (Case #824A) shares identical pinout with MC68HC705B16CFN and MC68HC705J1ACFN per Figures 1-5 and 14-7 of the Rev. 3 datasheet. However, it is not pin-compatible with 40-pin PDIP or 32-pin variants like MC68HC705P6ACD due to differing pin counts and signal allocations-mechanical and electrical compatibility must be verified per package type before substitution.