NXP Semiconductors MC908JB8JDWE

Overview

MC908JB8JDWE from Freescale Semiconductor is an 8-bit HCS08 microcontroller featuring 8 KB on-chip FLASH, 512 B RAM, integrated USB 1.1 low-speed interface (1.5 Mbps), and a 20-pin SOIC package. It operates at up to 8 MHz bus frequency, supports in-circuit programming via MON ROM, and includes TIM, KBI, COP, LVI, and 5-port I/O for embedded control applications.

For engineers reviewing the MC908JB8JDWE datasheet, MC908JB8JDWE pinout, MC908JB8JDWE application, or MC908JB8JDWE equivalent, this page delivers verified technical context, validated pin functions, real-world use cases, and confirmed alternative options for industrial sensor nodes, USB peripheral controllers, and low-power human-interface devices.

Technical Context

The MC908JB8JDWE implements the HCS08 CPU core with enhanced addressing modes and a 16-bit index register. Its USB module integrates a dedicated voltage regulator, differential transceiver, and full endpoint control logic compliant with USB Specification Rev. 1.1 for low-speed operation only.

It features a programmable 8-bit TIM with input capture, output compare, and PWM generation; a keyboard interrupt module supporting up to 8-key matrix scanning; and a configurable COP watchdog with selectable timeout intervals (1.0–4.1 ms). All peripherals are clocked from the internal bus clock derived from the crystal oscillator or external source.

Key Specifications

Pinout & Package

MC908JB8JDWE is housed in a 20-pin SOIC package (case 751BD-03) with 0.300" body width and standard 0.050" pitch. Pin assignments are defined per Section 1.5 of the MC68HC908JB8/D Rev. 2.3 datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908JB8JDWE, MC908JB16CDWE offers double FLASH capacity in identical packaging for seamless scalability, while MC9S08QG8CDTE trades integrated USB for broader S08 ecosystem compatibility and lower unit cost where USB is handled externally.

Availability

MC908JB8JDWE is available at Aetrix Electronics and suitable for USB peripheral controllers, industrial sensor interfaces, and embedded HID devices requiring stable component supply, long-term manufacturability, and legacy design continuity.

Supply support for MC908JB8JDWE 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 global leader in embedded processing solutions, delivering high-reliability microcontrollers for automotive, industrial, and consumer applications.

The MC908JB8JDWE belongs to the HCS08 microcontroller family, designed specifically for cost-sensitive, low-power USB-enabled embedded systems requiring integrated analog and digital peripherals without external support chips.

FAQ

What is the maximum operating frequency of the MC908JB8JDWE?

The MC908JB8JDWE supports a maximum bus frequency of 8 MHz, derived from its internal oscillator circuit or external clock source. This frequency governs instruction execution speed, timer resolution, and USB bit timing accuracy. The core runs at the same bus frequency, and all peripherals-including TIM, KBI, and USB-are synchronized to this clock domain. Performance remains stable across the full 2.7–5.5 V supply range.

Does the MC908JB8JDWE include an integrated USB transceiver?

Yes, the MC908JB8JDWE integrates a full USB 1.1 low-speed (1.5 Mbps) transceiver with differential D+ and D– drivers, receiver circuitry, and an on-chip 3.3 V voltage regulator. This eliminates the need for external USB PHY components. The transceiver is accessible via PTE3/D+ and PTE4/D– pins and complies with USB electrical specifications for low-speed device operation only.

Can the MC908JB8JDWE be programmed in-circuit without a dedicated programmer?

Yes, the MC908JB8JDWE includes a factory-programmed Monitor ROM (MON) that enables in-system programming via UART using standard terminal commands. This feature allows firmware updates and initial programming directly through the target system's serial interface-no external debugger or programmer is required. The MON ROM occupies fixed memory space and is accessible after reset when the RST pin is held low during power-up.

What low-power modes does the MC908JB8JDWE support?

The MC908JB8JDWE supports Wait and Stop modes. In Wait mode, the CPU halts but bus clock continues, allowing peripherals like TIM or KBI to generate interrupts and wake the core. In Stop mode, all clocks stop except for the LVI and COP modules, achieving ultra-low current draw (<1 µA typical). Both modes retain RAM contents and can be exited via IRQ, KBI, or COP timeout events.

Is the MC908JB8JDWE pin-compatible with other members of the JB8 family?

Yes, the MC908JB8JDWE shares identical pinout and package (20-pin SOIC) with MC908JB8CDWE and MC908JB8MDWE. Differences between these variants are limited to FLASH configuration (e.g., security settings), temperature grade, and packaging markings-not pin function or electrical behavior. This ensures PCB design reuse across commercial, extended, and industrial temperature versions of the same base part.