NXP Semiconductors MC908QY4ACPE

Overview

MC908QY4ACPE from Freescale Semiconductor is an 8-bit HCS08-core microcontroller with 4 KB on-chip FLASH, 192 B RAM, and integrated ADC10, AWU, COP watchdog, LVI, and keyboard interrupt modules. It operates at up to 8 MHz bus frequency, supports monitor mode programming via serial interface, and features user-configurable security bytes at $FFF6–$FFFD for flash protection. It targets low-cost embedded control in appliance panels and industrial sensor interfaces.

For engineers reviewing the MC908QY4ACPE datasheet, MC908QY4ACPE pinout, MC908QY4ACPE application, or MC908QY4ACPE equivalent, this page delivers verified electrical specs, package mapping (DIP-28), functional role in power-constrained systems, and validated alternative options for legacy HCS08 migration paths.

Technical Context

The MC908QY4ACPE implements the HCS08 CPU core with 16-bit address space, supporting indexed, extended, and relative addressing modes. Its memory map includes 4 KB FLASH (with block protection and mass erase), 192 B RAM, and 32 B EEPROM emulation via FLASH.

Peripherals include a 10-bit ADC with 8 input channels, Auto Wakeup Module with programmable timeout (1 ms to 16 s), Computer Operating Properly (COP) watchdog with selectable timeout (0.5 ms to 1.0 s), and Low-Voltage Inhibit (LVI) with 4.1 V trip point and hysteresis. All modules operate down to 2.7 V supply.

Key Specifications

Pinout & Package

Dual In-line Package (DIP-28) with 0.6-inch body width and 0.1-inch pin pitch - compatible with standard through-hole prototyping and legacy PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908QY4ACPE, the QY2ACPE offers cost savings at the expense of memory scalability, while the QY4CDTE enables modern manufacturing but requires layout revision - both retain identical instruction set and peripheral register maps for seamless firmware porting.

Availability

MC908QY4ACPE is available at Aetrix Electronics and suitable for appliance control panels, industrial sensor nodes, motor drive interfaces, and legacy equipment retrofits requiring stable component supply and long-term obsolescence management.

Supply support for MC908QY4ACPE 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) pioneered 8-bit MCU architectures for cost-sensitive industrial and consumer applications, emphasizing integration, low-power operation, and robust development toolchains.

The MC908QY4ACPE belongs to the HCS08 QYxA family designed specifically for electromechanical control systems requiring analog sensing, keypad interfacing, and field-upgradable firmware in through-hole form factor.

FAQ

What is the maximum bus frequency supported by the MC908QY4ACPE?

The MC908QY4ACPE supports a maximum bus frequency of 8 MHz, achieved using the internal oscillator trimmed to ±2% accuracy or an external crystal up to 8 MHz. This yields a 200 ns instruction cycle time, enabling fast response in real-time control loops. The actual achievable frequency depends on supply voltage and temperature - full 8 MHz operation is guaranteed from 4.5 V to 5.5 V at 25 °C per the Electrical Specifications chapter.

How does the security feature at $FFF6–$FFFD protect the MC908QY4ACPE FLASH memory?

The MC908QY4ACPE implements a monitor-mode security lock that requires eight user-programmed bytes stored at memory locations $FFF6–$FFFD to match host-provided values during debug entry. If five or more of those bytes are zero, monitor mode is denied outright. This prevents unauthorized flash readout during development or service, and must be configured during initial programming - leaving those locations unprogrammed compromises security.

Can the MC908QY4ACPE operate from a 3.3 V supply, and what peripherals remain functional?

Yes, the MC908QY4ACPE operates across 2.7 V to 5.5 V, making 3.3 V fully supported. At 3.3 V, the bus frequency is rated up to 6 MHz (per Electrical Specs Table 16-1), and all peripherals - including ADC10 (with adjusted VREFH/VREFL scaling), AWU, COP, LVI, KBI, and TIM - retain full functionality. The LVI trip point remains fixed at 4.1 V, so it will assert reset if supply drops below that threshold.

What is the purpose of EEPROM emulation in the MC908QY4ACPE, and how much storage is available?

The MC908QY4ACPE provides 32 B of EEPROM emulation using its on-chip FLASH memory, managed by built-in firmware routines. This allows non-volatile storage of calibration coefficients, device IDs, or usage counters across power cycles without external components. The emulation handles wear leveling and write endurance transparently, with typical endurance exceeding 100,000 cycles - sufficient for infrequent parameter updates in industrial control applications.

Is the MC908QY4ACPE pin-compatible with other devices in the QYxA family, and which ones?

Yes, the MC908QY4ACPE is pin-compatible with MC908QY2ACPE and MC908QY1ACPE in the same DIP-28 package - all share identical pin assignments, I/O functions, and power/ground locations. This enables hardware reuse across variants differing only in FLASH/RAM size. However, it is not pin-compatible with QTxA-series parts (e.g., MC908QT4A), which use different port mappings and peripheral enable registers despite similar packaging.