NXP Semiconductors MC68HC908JB12JDW

Overview

MC68HC908JB12JDW from Freescale Semiconductor is an 8-bit HCS08 microcontroller with 12.288 KB Flash, 384 B RAM, and integrated USB transceiver supporting low-speed (1.5 Mbps) device mode. It features a 20-pin SOIC package, 3.3 V internal voltage regulator (VREG), and operates from 0 °C to +70 °C. Used in embedded USB peripherals such as HID devices and industrial control interfaces.

For engineers reviewing the MC68HC908JB12JDW datasheet, MC68HC908JB12JDW pinout, MC68HC908JB12JDW application, or MC68HC908JB12JDW equivalent, key selection criteria include USB D+/D− pullup configuration, PTD0/1 combined sink capability (45 mA), VREG LVI trip point (1.9–2.6 V), and absence of dual clock generator module.

Technical Context

The MC68HC908JB12JDW implements the M68HC08 CPU core with on-chip monitor ROM (1.472 KB), flash memory mapped from $CA00–$F9FF, and I/O registers at $0000–$007F. Its USB interface uses open-drain PTE3/D+ and PTE4/D– pins with software-controllable 1.5 kΩ or 5 kΩ pullups to VREG or VDD.

Unlike the JB16 variant, the JB12 omits the dual clock generator module (registers $0051–$0059 unimplemented) and supports only 20-pin and 28-pin SOIC packages. The PTD0/1 pin bonds internal pads together, requiring DDRD0 = DDRD1 for consistent direction control and enabling 45 mA sink capability in ILDD mode.

Key Specifications

Pinout & Package

MC68HC908JB12JDW is housed in a 20-pin SOIC package (Case No. 751D), 12.65–12.95 mm × 7.40–7.60 mm, 2.35–2.65 mm height, with 1.27 mm pitch. Pin 1 is OSC1; pins 13–14 are VREG and VDD; pins 19–20 are VSS and PTD0/1 (bonded).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit USB microcontroller applications.

Compared with MC68HC908JB16JDW, the MC68HC908JB12JDW trades 4 KB Flash and CGM capability for lower cost and identical USB/peripheral integration in 20-pin SOIC. Against MC9RS08KA2CSC, it delivers full USB device capability without external components-critical for compact, certified USB endpoints.

Availability

MC68HC908JB12JDW is available at Aetrix Electronics and suitable for industrial keypad controllers, USB HID peripherals, embedded serial-to-USB bridges, and sensor node interfaces requiring stable component supply across extended production lifecycles.

Supply support for MC68HC908JB12JDW 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 microcontrollers, analog, and connectivity solutions for automotive, industrial, and consumer markets.

The MC68HC908JB12JDW belongs to the HCS08 family, designed specifically for cost-sensitive, USB-enabled embedded control applications requiring integrated analog peripherals, robust I/O, and minimal external components.

FAQ

What is the maximum sink current capability of the PTD0/1 pin on the MC68HC908JB12JDW?

The PTD0/1 pin on the MC68HC908JB12JDW provides a maximum sink current of 45 mA when configured as an output in ILDD mode. This capability is enabled only when DDRD0 and DDRD1 are set identically, as both internal pads are bonded to the single PTD0/1 terminal in the 20-pin SOIC package. Exceeding this limit may cause output voltage rise or thermal stress.

Does the MC68HC908JB12JDW include an integrated USB transceiver?

Yes, the MC68HC908JB12JDW integrates a low-speed USB 1.1 transceiver with dedicated D+ and D– pins (PTE3 and PTE4). It supports USB device enumeration without external PHY components. Pullup resistors on these pins are software-configurable to either 1.5 kΩ (to VREG) or 5 kΩ (to VDD), ensuring compliance with USB specification requirements.

What is the VREG LVI trip point range for the MC68HC908JB12JDW?

The VREG LVI (Low-Voltage Inhibit) trip point for the MC68HC908JB12JDW is specified as 1.9 V (minimum), 2.2 V (typical), and 2.6 V (maximum). This threshold triggers a reset when the internal 3.3 V regulator output falls below the minimum value, protecting against unreliable operation during power brownout conditions.

Which memory resources are available on the MC68HC908JB12JDW?

The MC68HC908JB12JDW includes 12,288 bytes of user Flash memory ($CA00–$F9FF), 384 bytes of RAM ($0080–$01FF), 1,472 bytes of monitor ROM, and 48 bytes of Flash vectors ($FFD0–$FFFF). The memory map reserves $0000–$007F for I/O registers and leaves $0200–$C9FF unimplemented, distinguishing it from larger variants like the JB16.

Is the dual clock generator module present in the MC68HC908JB12JDW?

No, the dual clock generator module is not implemented in the MC68HC908JB12JDW. Registers $0051–$0059 related to the CGM are unimplemented, and associated functionality-including programmable clock synthesis-is absent. This omission differentiates the JB12 from the JB16 and simplifies timing design for fixed-frequency USB and peripheral operation.