MC908JB16FAE
MC908JB16FAE - 8-Bit HC08 MCU, 16KB Flash, USB, 32-LQFP | NXP
The NXP MC908JB16FAE is an 8-bit HC08 CISC microcontroller integrating a full-speed USB 1.1 device controller, 16 KB of on-chip Flash program memory, and 384 B of RAM in a 32-pin LQFP package (7x7 mm). It targets low-cost USB peripherals such as HID-class input devices, USB-to-UART bridges, and human-interface dongles, replacing external USB serializer ICs with an integrated MCU+USB combination.
A microcontroller (MCU) is a single-chip computer that combines a CPU core, program memory (Flash/ROM), working memory (RAM), and a set of peripheral interfaces (USB, timers, ADC, GPIO, SCI). The MC908JB16FAE belongs to the Freescale/NXP HC08 family of 8-bit CISC microcontrollers, the predecessor to the S08 and Kinetis families. By embedding a USB 1.1 (full-speed, 12 Mbps) device transceiver with on-chip 3.3 V regulator and 1.5 kΩ software-configurable pull-up on the D- line, this MCU eliminates the discrete PHY + serial-jtag converter required by earlier 8051-based USB designs, simplifying BOM and reducing board area.
Key features include 6 MHz internal bus clock, 21 general-purpose I/O pins (shared with USB, SCI, timer, and interrupt functions), built-in peripherals (LED driver, low-voltage detect, power-on reset, PWM, SCI), 16 KB Flash program memory with in-application programming support, 384 B RAM, and a 32-pin LQFP industrial-grade operating range of 0 C to +70 C (industrial variants available). The integrated USB module supports control, interrupt, bulk, and isochronous endpoints, sufficient for HID, CDC/ACM, and vendor-class device firmware.
The HC08 CPU core uses a Von Neumann memory architecture with a 16-bit stack pointer and a small unified instruction set optimized for code density (typical instructions are 1-3 bytes). The internal oscillator and phase-locked loop allow flexible system clock generation without an external crystal in some configurations, while the USB module requires a 48 MHz clock derived from the PLL for full-speed signaling. This architecture trades raw clock speed (6 MHz) for low power and deterministic interrupt latency, which suits HID polling loops and low-bandwidth USB CDC streams.
Typical applications include USB HID peripherals (mice, keyboards, custom input devices), USB-to-UART bridge dongles (replacing FTDI-style cables), embedded USB learning kits, industrial data-loggers with USB diagnostics, and point-of-sale peripherals. The integrated pull-up and embedded voltage regulator mean a USB device can be built with this MCU plus a few passives, no external USB PHY chip required.
When designing with this part, note that the HC08 instruction set, while capable, requires the legacy CodeWarrior HC08 toolchain (now superseded by S08/Kinetis tools); firmware migration to newer NXP families is recommended for new designs. USB firmware must implement the device-state machine per USB 1.1 specification to achieve enumeration. For new designs, consider the Freescale/NXP S08JM60 or Kinetis KE series as modern drop-in USB-enabled successors, though they require new toolchains and may differ in peripheral mapping.
This page synthesizes distributor pricing, pin-compatible alternatives, application references, and practical design notes that are not collated in the manufacturer datasheet alone.
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