NXP Semiconductors MC705P6ACPE

Overview

MC705P6ACPE from Freescale Semiconductor is an 8-bit EPROM-based microcontroller in the M68HC05 family, featuring a 16-bit timer with input capture/output compare, 4-channel 8-bit ADC, SIOP serial interface, COP watchdog, 4672 bytes of user EPROM, 176 bytes of RAM, and 21 I/O pins (20 bidirectional + 1 input-only). It targets cost-sensitive embedded control in industrial sensors and appliance motor controllers.

For engineers reviewing the MC705P6ACPE datasheet, MC705P6ACPE pinout, MC705P6ACPE application, or MC705P6ACPE equivalent, key selection criteria include its 5 V operation, mask-programmable MOR options (COP enable/disable, IRQ sensitivity, SIOP MSB/LSB order), PDIP-28 package compatibility, and bootloader ROM support for field programming.

Technical Context

The MC705P6ACPE implements the M68HC05 CPU core with static logic, supporting STOP/HALT/WAIT low-power modes and a fixed 2 MHz internal bus clock derived from OSC1/OSC2 (f_osc/2). Its analog subsystem uses ratiometric A/D conversion referenced to VREFH, with conversion times dependent on oscillator source.

Timer functionality includes one input capture channel (PD7/TCAP) and one output compare channel (TCMP), both mapped to dedicated pins and controlled via Timer Control and Status Registers. The SIOP operates in master/slave mode with programmable clock dividers (OSC/8, /16, /32, /64) and configurable bit-order (MSB or LSB first).

Key Specifications

Pinout & Package

MC705P6ACPE is housed in a 28-pin PDIP (Plastic Dual In-Line Package), case 710, with 0.6-inch body width and standard 0.1-inch pin pitch. Pin 1 is marked by a notch or dot; pin numbering proceeds counter-clockwise.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC68HC705P6CDW and MC68HC705P6MFA, the MC705P6ACPE offers verified long-term stability in PDIP packaging, direct compatibility with legacy through-hole designs, and guaranteed EPROM retention over 10 years - making it optimal for industrial replacement and maintenance programs.

Availability

MC705P6ACPE is available at Aetrix Electronics and suitable for industrial sensor nodes, home appliance motor controllers, and smart power outlets requiring stable component supply, long-lifecycle support, and drop-in compatibility with existing M68HC05P6-based designs.

Supply support for MC705P6ACPE 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) is a fabless semiconductor company specializing in embedded processing, analog, and connectivity solutions for automotive, industrial, and consumer markets.

The MC68HC705P6A belongs to the M68HC05 microcontroller family, designed for cost-sensitive, low-pin-count embedded control applications where integration of ADC, timer, and serial interface reduces BOM count and board area.

FAQ

What is the maximum operating frequency of the MC705P6ACPE?

The MC705P6ACPE derives its internal bus clock from the oscillator input at OSC1/OSC2, dividing the crystal or resonator frequency by two. With a nominal 4 MHz crystal, the internal bus clock runs at 2 MHz. The device is rated for reliable operation up to 4 MHz oscillator input (2 MHz bus clock), as confirmed in Chapter 14 Electrical Specifications of the Rev. 2.1 datasheet. Exceeding this limit risks timing violations in the SIOP, timer, and ADC subsystems. The MC705P6ACPE does not support higher frequencies via internal PLL or frequency multipliers.

Does the MC705P6ACPE support in-system programming (ISP)?

Yes, the MC705P6ACPE supports in-system programming via its built-in bootloader ROM. Using the SIOP interface (PB5/SDO, PB6/SDI, PB7/SCK), firmware can be reprogrammed while soldered on the target board - provided the MOR enables bootloader mode and VPP is applied to IRQ/VPP during programming. This eliminates the need for socketed EPROM programmers. The 239-byte bootloader handles command parsing, address decoding, and EPROM write/verify cycles, making the MC705P6ACPE suitable for field-upgradable devices.

How is the analog reference voltage (VREFH) configured on the MC705P6ACPE?

VREFH is supplied externally to pin PC7 and sets the upper reference for all four ADC channels. The MC705P6ACPE uses ratiometric conversion, meaning the ADC result is proportional to V_IN/VREFH. For accurate measurements, VREFH must be stable and noise-free - typically derived from a precision voltage reference or filtered +5 V supply. The datasheet specifies VREFH must remain within 1.0 V to VDD; operation outside this range invalidates ADC linearity and accuracy. No internal reference generator is present, so external sourcing is mandatory.

Can the MC705P6ACPE operate from a 3.3 V supply?

No, the MC705P6ACPE is specified exclusively for 5.0 V ±10% operation. Chapter 14 Electrical Specifications lists absolute maximum ratings and DC characteristics only for VDD = 5.0 V, with no 3.3 V parameterization. Attempting 3.3 V operation results in undefined behavior: insufficient noise margin causes erratic SIOP communication, failed COP resets, and unreliable ADC conversions. The internal oscillator, CPU core, and EPROM programming circuitry all require 5 V compliance. For 3.3 V systems, designers must use level-shifting interfaces or select a modern 3.3 V–compatible MCU.

What debug or development tools are compatible with the MC705P6ACPE?

The MC705P6ACPE supports debugging via its COP watchdog timer and RESET pin, but lacks on-chip JTAG or BDM interfaces. Development relies on external EPROM programmers (e.g., BP Microsystems units) for initial code loading, and the integrated bootloader for subsequent updates via SIOP. Freescale's legacy DEMO705P6 evaluation board provides socketed PDIP support, oscillator circuitry, and SIOP header connections - enabling hardware validation before custom PCB spin. No official IDE exists today, but assembly toolchains (e.g., AS68HC05) and open-source simulators remain functional for legacy code maintenance.