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NXP Semiconductors MC68HC908JB8ADW
- Part No.:
- MC68HC908JB8ADW
- Manufacturer:
- NXP Semiconductors
- Category:
- Microcontrollers
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
MC68HC908JB8ADW.pdf
- Description:
- IC MCU 8BIT 8KB FLASH 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,572
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Product details
Overview
MC68HC908JB8ADW from Freescale Semiconductor is an 8-bit HCS08 microcontroller with 8 KB on-chip FLASH, 512 B RAM, and integrated USB 1.1 low-speed device controller. It features a 20 MHz CPU bus speed, 24 I/O pins, and supports in-system programming via MON ROM. Used in embedded USB peripherals such as industrial HID devices and sensor interfaces requiring compact, cost-optimized MCU solutions.
For engineers reviewing the MC68HC908JB8ADW datasheet, MC68HC908JB8ADW pinout, MC68HC908JB8ADW application, or MC68HC908JB8ADW equivalent, key selection criteria include its USB transceiver integration, 20-pin SOIC package, 2.7–5.5 V operating range, and ROM-resident bootloader for field firmware updates.
Technical Context
The MC68HC908JB8ADW implements the HCS08 CPU core with enhanced addressing modes and low-power STOP/WAIT modes. Its USB module complies with USB 1.1 specification for low-speed (1.5 Mbps) operation and includes integrated voltage regulator, differential transceiver, and endpoint buffers for control (EP0), interrupt (EP1), and bulk (EP2) transfers.
Memory architecture integrates 8 KB FLASH with block protection, 512 B RAM, and 2 KB monitor ROM containing flash programming routines and serial bootloader. Clock system supports crystal (1–8 MHz), ceramic resonator, or external clock input with internal PLL for bus frequency scaling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| CPU Core | HCS08 8-bit CISC core with 24-bit address space and 16-bit index register - enables efficient memory-mapped peripheral access and compact code density. |
| FLASH Memory | 8 KB on-chip FLASH with 128-byte block erase and mass erase - supports field firmware updates without external programmer. |
| RAM | 512 bytes of on-chip RAM - sufficient for real-time USB descriptor handling and small application stacks. |
| USB Interface | Integrated USB 1.1 low-speed device controller (1.5 Mbps) with D+/D− pins and internal 3.3 V regulator - eliminates need for external PHY or LDO in basic HID designs. |
| Operating Voltage | 2.7 V to 5.5 V - allows direct interface with 3.3 V logic or legacy 5 V systems without level-shifting. |
| Package | 20-pin SOIC (Small Outline Integrated Circuit), case 751B-03 - compatible with standard surface-mount assembly and reflow profiles. |
| Max Bus Frequency | 20 MHz - delivers ~10 MIPS performance suitable for USB polling, sensor sampling, and HID report generation. |
Pinout & Package
MC68HC908JB8ADW is housed in a 20-pin SOIC package (case 751B-03) with 0.3 inch body width and 0.050 inch lead pitch. Pinout conforms to Freescale's standard HCS08 JB8 variant layout, supporting single-supply operation and integrated USB signaling.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD | Power supply input | Primary 2.7–5.5 V supply for core, I/O, and USB regulator - must be decoupled with 0.1 µF ceramic capacitor near pin. |
| VSS | Ground reference | Digital ground return for all internal circuits and I/O ports - requires low-impedance connection to PCB ground plane. |
| OSC1 / OSC2 | Clock oscillator terminals | Connects to 1–8 MHz crystal or ceramic resonator - determines base clock source for USB timing and CPU operation. |
| RST | Active-low reset input | Asynchronous reset pin; held low during power-up or brownout - triggers POR sequence and initializes all registers. |
| PTE3/D+ / PTE4/D− | USB differential data lines | Direct connection to USB host D+ and D− lines - no external termination resistors required due to integrated 1.5 kΩ pull-up on D+. |
| PTA0–PTA7 | Port A bidirectional I/O | 8-bit general-purpose port with individual direction control - supports keyboard scan matrix or digital sensor inputs. |
| PTB0–PTB7 | Port B bidirectional I/O | 8-bit general-purpose port with weak pull-ups - usable for LED drive, switch sensing, or SPI slave interface. |
| PTC0–PTC7 | Port C bidirectional I/O | 8-bit port with KBI interrupt capability - enables wake-from-sleep on keypress without CPU active. |
Key Features
| Feature | Design Value |
|---|---|
| ROM-resident monitor (MON) | 2 KB on-chip ROM containing flash programming routines and UART-based bootloader - enables firmware updates over RS-232 without JTAG hardware. |
| USB 1.1 low-speed device controller | Fully integrated transceiver with internal 3.3 V regulator and D+ pull-up - reduces BOM count by eliminating external PHY and LDO. |
| Flash block protection | Configurable 128-byte block lock bits - prevents accidental overwrite of bootloader or critical application code during field updates. |
| Keyboard interrupt (KBI) module | 8-input scan-capable interrupt controller with wake-from-stop capability - supports low-power human-interface devices with <1 µA standby current. |
| Computer Operating Properly (COP) watchdog | Programmable timeout (0.5 ms to 1.0 s) with independent clock source - ensures fail-safe recovery from software hangs in safety-critical functions. |
Applications
| Industrial HID Device | USB Sensor Node |
|---|---|
Use Scenario: Compact USB-connected pushbutton panel for PLC control or machine status indication. IC Role / Device Role / Timing Role: Primary MCU executing HID report generation, button debouncing, and USB enumeration. Use Value: Integrated USB transceiver and MON ROM eliminate external components, reducing PCB area and enabling firmware updates via standard COM port. |
Use Scenario: Battery-powered environmental sensor (temperature/humidity) reporting via USB to host PC or gateway. IC Role / Device Role / Timing Role: System controller managing ADC sampling, data formatting, and USB interrupt endpoint transmission. Use Value: Low-voltage operation (2.7 V) extends battery life; KBI and STOP mode allow wake-on-sensor-event with sub-µA quiescent current. |
| Embedded Keypad Interface | Legacy Equipment USB Adapter |
Use Scenario: Retrofit keypad for older industrial equipment requiring USB connectivity instead of PS/2 or serial. IC Role / Device Role / Timing Role: Protocol translator mapping matrix scan to USB HID keyboard reports. Use Value: On-chip 8 KB FLASH stores HID descriptor tables and translation logic; no external memory needed. |
Use Scenario: USB-to-parallel/serial adapter for legacy test instruments lacking native USB support. IC Role / Device Role / Timing Role: Bridge controller handling USB setup transactions and parallel port bit-banging. Use Value: 24 GPIO pins provide flexible I/O mapping; MON ROM enables field-upgradable protocol firmware without dedicated programmer. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microcontroller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC9RS08KA2 | RS08 core, 2 KB FLASH, no integrated USB - requires external USB-to-UART bridge for USB connectivity. | Lacks native USB device stack; suitable only when USB is implemented externally or omitted. | Select if lower cost and smaller footprint are prioritized over integrated USB functionality. |
| MC9S08QG8 | S08 core, 8 KB FLASH, USB 2.0 full-speed capable - larger 44-pin QFP package and higher power consumption. | Supports higher-bandwidth USB applications (e.g., audio streaming) but increases PCB size and BOM complexity. | Choose when full-speed USB (12 Mbps) or additional peripherals (e.g., CAN, LIN) are required. |
Compared with MC9RS08KA2 and MC9S08QG8, the MC68HC908JB8ADW uniquely balances native low-speed USB integration, compact 20-pin SOIC packaging, and sufficient memory for HID-class firmware - making it optimal for space-constrained, cost-sensitive USB peripheral designs where full-speed bandwidth is unnecessary.
Availability
MC68HC908JB8ADW is available at Aetrix Electronics and suitable for industrial HID devices, USB sensor nodes, and legacy equipment adapters requiring stable component supply and long-term manufacturability.
Supply support for MC68HC908JB8ADW 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, delivering high-performance, energy-efficient microcontrollers and analog solutions for automotive, industrial, and consumer markets.
The MC68HC908JB8ADW belongs to Freescale's HCS08 microcontroller family, designed specifically for cost-sensitive, USB-enabled embedded peripherals requiring robust in-field programmability and low-power operation.
FAQ
What is the maximum operating frequency of the MC68HC908JB8ADW?
The MC68HC908JB8ADW supports a maximum bus frequency of 20 MHz, achieved using its internal PLL with an external 1–8 MHz crystal or resonator on OSC1/OSC2. This yields approximately 10 MIPS performance, sufficient for real-time USB descriptor handling, HID report generation, and sensor data acquisition without external acceleration.
Does the MC68HC908JB8ADW require an external USB transceiver?
No, the MC68HC908JB8ADW integrates a complete USB 1.1 low-speed (1.5 Mbps) transceiver with internal 3.3 V regulator and D+ pull-up resistor. Only passive ESD protection diodes and optional series resistors are recommended on D+/D− lines - no external PHY chip is needed for basic HID or CDC device implementations.
How is firmware updated on the MC68HC908JB8ADW in the field?
Firmware updates for the MC68HC908JB8ADW are performed using its 2 KB monitor ROM (MON), which contains flash programming routines accessible via UART. Engineers can use standard terminal software to send S-record files over RS-232, eliminating the need for JTAG debuggers or external programmers during field deployment or maintenance.
What low-power modes does the MC68HC908JB8ADW support?
The MC68HC908JB8ADW supports WAIT and STOP modes. In STOP mode, current drops below 1 µA while retaining RAM contents and allowing wake-up via IRQ, KBI, or USB resume. This makes it suitable for battery-powered USB peripherals that spend most time idle but must respond rapidly to host requests or user input.
Is the MC68HC908JB8ADW pin-compatible with other HCS08 family members?
The MC68HC908JB8ADW uses a 20-pin SOIC package shared with MC68HC908JB12ADW and MC68HC908JT8 variants, but pin functions differ across models - especially USB-related signals (PTE3/D+, PTE4/D−) and oscillator configuration. Direct substitution requires verification of signal mapping, memory size, and peripheral enablement in the target application.
MC68HC908JB8ADW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- Series:
- HC08
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Core Processor:
- HC08
- Core Size:
- 8-Bit
- Speed:
- 3MHz
- Connectivity:
- USB
- Peripherals:
- LVD, POR, PWM
- Number of I/O:
- 21
- Program Memory Size:
- 8KB (8K x 8)
- Program Memory Type:
- FLASH
- EEPROM Size:
- -
- RAM Size:
- 256 x 8
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 5.5V
- Data Converters:
- -
- Oscillator Type:
- Internal
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
MC68HC908JB8ADW FAQ
1.How can I place an order for MC68HC908JB8ADW through Aetrix?
Please submit a Request for Quotation (RFQ) for MC68HC908JB8ADW on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MC68HC908JB8ADW reliable?
The price and inventory of MC68HC908JB8ADW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC68HC908JB8ADW is usually 5 days.
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MC68HC908JB8ADW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC68HC908JB8ADW order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MC68HC908JB8ADW?
For technical support, including MC68HC908JB8ADW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC68HC908JB8ADW requirements.
6.How does Aetrix verify that MC68HC908JB8ADW is sourced from the original manufacturer or authorized distributors?
All MC68HC908JB8ADW products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MC68HC908JB8ADW meets industry standards.
7.What is the process for return or replacement of MC68HC908JB8ADW?
All MC68HC908JB8ADW units undergo pre-shipment inspection (PSI). If there is an issue with MC68HC908JB8ADW, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MC68HC908JB8ADW part is unused and in its original packaging.
Return procedure for MC68HC908JB8ADW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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