NXP Semiconductors MCHSC705C8ACFNE

Overview

MCHSC705C8ACFNE from Freescale Semiconductor is an 8-bit HCS05 microcontroller unit (MCU) featuring 8 KB on-chip flash memory, 256 bytes RAM, and a 4 MHz internal oscillator. It integrates a 16-bit timer, analog-to-digital converter (ADC), and serial communication interface (SCI). It is used in low-cost embedded control applications such as appliance motor control and industrial sensor interfaces.

For engineers reviewing the MCHSC705C8ACFNE datasheet, MCHSC705C8ACFNE pinout, MCHSC705C8ACFNE application, or MCHSC705C8ACFNE equivalent, key selection considerations include flash endurance (10,000 write/erase cycles), operating voltage range (2.7–5.5 V), and support for single-chip mode without external clock components.

Technical Context

The MCHSC705C8ACFNE belongs to the Motorola/Freescale HCS05 family, built on CMOS technology with mask-programmable ROM variants superseded by flash-based versions. It executes code from on-chip flash and supports in-system programming via the background debug mode (BDM) interface.

It features a 16-bit index register, 8-bit accumulator, and condition code register - compatible with HC05 instruction set architecture. The MCU includes a 4-channel 8-bit ADC with software-selectable conversion time and a programmable SCI supporting asynchronous full-duplex communication at up to 9600 baud.

Key Specifications

Pinout & Package

Package: 52-pin QFP (Quad Flat Package), 10 mm × 10 mm body, 0.65 mm pitch - suitable for automated SMT assembly and moderate I/O density layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC9RS08KA2CFD and MC908JB8CDTE, the MCHSC705C8ACFNE uniquely balances field-upgradable flash, integrated ADC, and BDM debug - making it optimal for prototyping and mid-volume embedded control where flexibility and analog interfacing are required.

Availability

MCHSC705C8ACFNE is available at Aetrix Electronics and suitable for home appliance control, industrial sensor nodes, automotive body electronics, and consumer remote systems requiring stable component supply and long-term manufacturability.

Supply support for MCHSC705C8ACFNE 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 since 2015) was a leading designer of embedded processors, analog, and mixed-signal ICs for automotive, industrial, and consumer markets.

The MCHSC705C8ACFNE belongs to the HCS05 microcontroller family - designed for cost-sensitive, low-pin-count embedded control applications requiring flash programmability and integrated peripherals.

FAQ

What is the maximum operating frequency of the MCHSC705C8ACFNE?

The MCHSC705C8ACFNE operates at a maximum internal bus frequency of 4 MHz, derived from its on-chip oscillator. External clock sources up to 4 MHz may also be used via the OSC1/OSC2 pins. This frequency determines instruction execution speed and peripheral timing - for example, the SCI baud rate generator derives all timing from this clock source. The MCHSC705C8ACFNE does not support PLL multiplication or higher-frequency external crystals beyond its specified range.

Does the MCHSC705C8ACFNE support in-circuit debugging?

Yes, the MCHSC705C8ACFNE supports Background Debug Mode (BDM) via a single dedicated pin (BKGD), enabling non-intrusive program download, real-time register inspection, and breakpoint setting without requiring additional debug hardware. This capability is integral to the MCHSC705C8ACFNE design and requires only a BDM-compatible programmer - no JTAG adapter or external emulator is needed. BDM remains functional even when the MCHSC705C8ACFNE is running in single-chip mode.

What package type is used for the MCHSC705C8ACFNE?

The MCHSC705C8ACFNE is packaged in a 52-pin Quad Flat Package (QFP) with 10 mm × 10 mm body size and 0.65 mm lead pitch. This package is RoHS-compliant and designed for surface-mount reflow assembly. Pin assignments match the standard HCS05 52-pin footprint, ensuring mechanical compatibility with existing test fixtures and layout templates used for related Freescale MCUs like the MC68HC908JK3.

Can the MCHSC705C8ACFNE operate from a 3.3 V supply?

Yes, the MCHSC705C8ACFNE supports operation across 2.7–5.5 V, fully covering 3.3 V nominal supply rails. At 3.3 V, it maintains full functionality including flash programming, ADC conversions, and SCI communication - though maximum bus frequency is reduced to 3.3 MHz per electrical specifications. System designers must verify timing margins for critical peripherals when operating below 4 V, as the MCHSC705C8ACFNE's internal oscillator accuracy varies with voltage and temperature.

Is there a drop-in replacement for the MCHSC705C8ACFNE with more memory?

No verified pin-compatible or drop-in replacement with increased memory exists for the MCHSC705C8ACFNE. Higher-memory variants like the MCHSC705C16 use different pinouts and require PCB redesign. While the MC908JB16CDTE shares the same HCS05 core and 16 KB ROM, it lacks flash reprogrammability and uses a distinct 52-pin mapping. Migration to the RS08 or S08 families would require firmware rewrite and layout changes - the MCHSC705C8ACFNE remains the highest-flash option within its exact pinout and feature set.