NXP Semiconductors MC705C9ACPE

Overview

MC705C9ACPE from Freescale Semiconductor is an EPROM-based 8-bit HCMOS 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 3.0–5.5 V and supports wait/stop low-power modes for embedded control in industrial sensors and motor drives.

For engineers reviewing the MC705C9ACPE datasheet, MC705C9ACPE pinout, MC705C9ACPE application, or MC705C9ACPE equivalent, key selection criteria include EPROM programmability, C9A/C12A configuration flexibility via mask option registers, 31 I/O lines (including high-current PC7), and dual-voltage timing compliance (3.3 V and 5.0 V).

Technical Context

The MC705C9ACPE implements the M68HC05 CPU core with accumulator, index register, stack pointer, and condition code register. Its memory map supports configurable dual-mode operation-either as MC68HC05C9A (full 16 KB address space, dual-mapped RAM/EPROM) or MC68HC05C12A (reduced map, disabled $0100–$0FFF)-controlled by EPROM-programmed mask option registers (PBMOR at $3FF0, C12MOR at $3FF1).

It integrates three serial peripherals: SCI with idle-line/address-mark wakeup and baud rate generator; SPI with master/slave support, SS/MOSI/MISO/SCK on Port D pins; and a 16-bit timer supporting input capture, output compare, and operation in wait mode. COP reset and clock monitor are software-configurable only in C9A mode.

Key Specifications

Pinout & Package

MC705C9ACPE is packaged in a 40-pin plastic dual in-line (DIP) package (Case 711-03), with through-hole mounting and 0.6-inch width.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC705C8ACPE and MC68HC705P6ACPE, the MC705C9ACPE delivers the largest EPROM/RAM capacity and full serial peripheral complement (SCI + SPI) in the HC05Cxx EPROM series, making it the highest-integration option for legacy-compatible embedded control.

Availability

MC705C9ACPE is available at Aetrix Electronics and suitable for industrial motor control, smart sensor nodes, legacy equipment retrofit, and PLC I/O modules requiring stable component supply and long-term obsolescence management.

Supply support for MC705C9ACPE 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) designed high-reliability microcontrollers for automotive, industrial, and consumer applications before its 2015 acquisition.

The MC68HC05 family-including MC705C9ACPE-was engineered for cost-sensitive, resource-constrained embedded control, emphasizing EPROM programmability, low-power operation, and pin compatibility across mask-ROM variants.

FAQ

What is the maximum operating frequency of the MC705C9ACPE?

The MC705C9ACPE does not specify a maximum system clock frequency in its Advance Information Data Sheet. Operation relies on an external crystal or ceramic resonator connected to OSC1/OSC2; typical designs use 1–4 MHz crystals. The internal oscillator divides the crystal frequency by two, yielding a CPU clock of 0.5–2 MHz. Timing parameters in Chapter 12 assume operation within this range and are validated for both 3.3 V and 5.0 V supply conditions. Always verify timing margins against actual crystal tolerance and load capacitance in the final design.

Does the MC705C9ACPE support in-circuit programming?

No, the MC705C9ACPE does not support in-circuit programming. It is an EPROM-based microcontroller requiring UV erasure and parallel programming using a dedicated EPROM programmer. Programming occurs before soldering via the VPP pin (pin 1), which must be raised to 12.5 V ± 0.5 V during write cycles. The device includes a bootloader mode (Appendix A) for initial EPROM loading, but reprogramming in the target system is not supported. Field updates require physical chip replacement or use of external flash memory.

How is the C9A vs. C12A configuration selected on the MC705C9ACPE?

The C9A vs. C12A configuration is selected by programming two EPROM-based mask option registers: PBMOR ($3FF0) and C12MOR ($3FF1). When C12MOR bit 7 = 0, the device operates in MC68HC05C9A mode (full memory map, software-controlled IRQ/COP); when bit 7 = 1, it emulates MC68HC05C12A (reduced memory map, ROM-mask-controlled features). These registers are programmed once during EPROM burning and cannot be altered in-system. Configuration is verified by reading the registers after power-up, and incorrect programming may cause undefined reset behavior or peripheral disablement.

Can the MC705C9ACPE's Port D pins be used for general-purpose I/O when SPI is not active?

Yes, Port D pins (PD0–PD5, PD7) function as general-purpose I/O when SPI is disabled. Their roles are multiplexed: PD0=RDI, PD1=TDO, PD2=MISO, PD3=MOSI, PD4=SCK, PD5=SS. To use them as GPIO, clear the corresponding bits in the SPI Control Register (SPCR at $000A) and configure the Port D Data Direction Register ($0007) accordingly. Note that PD7 has no alternate function and is always available as GPIO. This flexibility allows shared pin usage between serial communication and discrete control in space-constrained designs.

What packaging options are available for the MC705C9ACPE?

MC705C9ACPE is offered exclusively in a 40-pin plastic dual in-line package (DIP) with 0.6-inch width (Case 711-03). This through-hole package is compatible with standard DIP sockets and wave-soldering processes. While the MC68HC705C9A datasheet lists SDIP, PLCC, and QFP variants for other part numbers, the "CPE" suffix specifically denotes the DIP-40 variant. No surface-mount or alternative lead-form versions exist for this orderable part number.