NXP Semiconductors MC908AP32ACFAE

Overview

MC908AP32ACFAE from Freescale Semiconductor is an 8-bit HCS08 microcontroller featuring 32 KB on-chip Flash memory, 1 KB RAM, and a 20 MHz CPU bus speed. It integrates a 10-bit ADC with 8 channels, SCI, SPI, I²C, and a 16-bit TIM module with input capture and PWM outputs. Designed for cost-sensitive industrial control and appliance applications requiring deterministic real-time response.

For engineers reviewing the MC908AP32ACFAE datasheet, MC908AP32ACFAE pinout, MC908AP32ACFAE application, or MC908AP32ACFAE equivalent, key selection criteria include Flash endurance (100k erase/write cycles), internal voltage regulator support (VREG pin), oscillator flexibility (RC/Xtal/PLL), and availability of monitor ROM for in-system programming.

Technical Context

The MC908AP32ACFAE implements the HCS08 core with enhanced addressing modes and a 16-level hardware stack. Its Clock Generator Module (CGM) supports PLL-based clock multiplication up to 20 MHz from internal RC or external crystal sources, enabling precise timing control for motor control loops and communication baud rate generation.

System integration includes a System Integration Module (SIM) managing reset sources (POR, LVI, COP), interrupt prioritization across 16 vectors, and low-power modes (Wait/Stop). The analog subsystem features a dedicated VDDA/VSSA pair and programmable ADC clock division (500 kHz–1 MHz), ensuring stable conversion accuracy under varying supply conditions.

Key Specifications

Pinout & Package

MC908AP32ACFAE is housed in a 64-pin QFP (Quad Flat Package) with 0.5 mm pitch, compliant with JEDEC MO-137AB. The package provides full I/O access including dedicated analog inputs, crystal connections, and regulator control pins.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908AP64ACFAE, the MC908AP32ACFAE offers identical peripherals and timing performance at lower memory cost; versus MC9S08AW32CFUE, it lacks CAN but provides superior I/O count and QFP thermal performance for industrial ambient conditions.

Availability

MC908AP32ACFAE is available at Aetrix Electronics and suitable for industrial motor control, home appliance UI, smart power metering, and automotive body control applications requiring stable component supply and long-term manufacturability.

Supply support for MC908AP32ACFAE 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 embedded systems, emphasizing robustness, low power, and toolchain maturity.

The MC908AP32ACFAE belongs to the HCS08 AP-family, designed specifically for appliance control, industrial automation, and metering applications where Flash endurance, analog integration, and monitor-mode programmability are critical.

FAQ

What is the maximum operating frequency of the MC908AP32ACFAE CPU bus?

The MC908AP32ACFAE supports a maximum CPU bus frequency of 20 MHz. This is achieved via the Clock Generator Module's PLL, which multiplies the internal RC oscillator or external crystal source. The actual bus speed depends on CGM configuration and is verified in Section 6.3.6 of the Rev. 3 datasheet. MC908AP32ACFAE maintains timing compliance across its full 2.7–5.5 V supply range at this frequency.

Does the MC908AP32ACFAE include an internal voltage regulator?

Yes, the MC908AP32ACFAE includes an integrated 3.3 V voltage regulator accessible via the VREG pin. It can be configured as either an output (supplying regulated power to external circuitry) or an input (accepting external 3.3 V for internal analog blocks). This regulator powers the ADC reference and internal oscillator circuitry, improving noise immunity. Configuration is controlled by the CONFIG1 register bit VREGEN, as documented in Chapter 3.

How many ADC channels does the MC908AP32ACFAE support, and what is their resolution?

The MC908AP32ACFAE supports eight 10-bit analog-to-digital converter channels (AD0–AD7), multiplexed onto Port B pins. Resolution is fixed at 10 bits with typical INL of ±1 LSB. The ADC clock must be set between 500 kHz and 1 MHz per Section 15.7.2; conversion time ranges from 25 to 50 µs depending on clock setting and sample time configuration. MC908AP32ACFAE uses a successive-approximation architecture with internal reference derived from VDDA or VREG.

Can the MC908AP32ACFAE enter low-power Stop mode while retaining RAM contents?

Yes, the MC908AP32ACFAE retains full 1 KB RAM contents in Stop mode when VDD remains ≥ 1.8 V. During Stop, the CPU, bus clocks, and most peripherals halt, but RAM, CONFIG registers, and certain wakeup sources (IRQ, KBI, RTC alarm) remain active. Exit occurs via external interrupt or reset. This behavior is confirmed in Section 4.5.2 and Table 22-4 (DC Electrical Characteristics) of the MC68HC908AP A-Family Data Sheet, Rev. 3.

What debug and programming interfaces are supported by the MC908AP32ACFAE?

The MC908AP32ACFAE supports in-circuit debugging and programming via its built-in Monitor ROM, accessed through the SCI interface using standard serial commands. No external JTAG or BDM hardware is required. The monitor enables flash erase, program, and verify operations at standard baud rates (e.g., 9600 or 19200 bps). Entry requires specific reset timing and break signal assertion, detailed in Chapter 8. MC908AP32ACFAE does not support background debug mode (BDM) or SWD.