MC68HC908JK8CDW - 8KB Flash 8-Bit HC08 MCU, 20-SOIC | NXP
MPN: MC68HC908JK8CDW ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.5 | $8.50 |
| 10 | $7.65 | $76.50 |
| 100 | $6.2 | $620.00 |
| 500 | $5.4 | $2,700.00 |
| 1,000 | $4.85 | $4,850.00 |
MC68HC908JK8CDW Overview
An 8-bit MCU (microcontroller unit) is a single-chip computer that integrates a CPU, RAM, program memory, and peripherals on one die, optimized for cost-sensitive embedded control. The HC08 architecture is a CISC (Complex Instruction Set Computer) design using a Von Neumann memory map, where program and data share the same address space - a hallmark of the Motorola/Freescale/NXP 68xx lineage. Within the broader taxonomy, the MC68HC908JK8 belongs to the 8-bit MCU segment of microcontrollers (MCU), which sits below 16-bit and 32-bit MCUs in processing power but excels in BOM-cost-sensitive applications.
Key features include 8KB FLASH program memory (8K x 8), 256 bytes of SRAM, 15 GPIO pins, an on-chip oscillator with trimming, and multiple power-saving modes. The device operates from a typical 5V supply (extended range supported) and integrates an LED drive capability that can source/sink sufficient current to directly control indicator LEDs without external transistors in many designs.
The HC08 core executes M68HC08 instruction set with enhanced addressing modes over the predecessor HC05 family. The integrated FLASH allows in-system reprogramming via the standard background debug mode (BDM), enabling field updates and reducing development-cycle time. The 8 MHz maximum bus frequency balances instruction throughput against power consumption for typical consumer and industrial control tasks.
Typical applications include appliance control panels, LED lighting controllers, simple motor drivers (small fans, pumps), remote-control transmitters, security keypads, and low-cost toy/consumer products. The combination of FLASH, PWM, and SCI in a 20-pin SOIC footprint makes it well-suited for compact, cost-constrained designs that still demand reprogrammability.
When designing with this part, ensure the supply voltage stays within the supported range and provision adequate decoupling (typically 100 nF plus a bulk cap) close to the VDD pins. For production programming, the BDM interface (BKGD/MS pins) is the standard path - plan the PCB to expose these test points for in-circuit firmware updates.
This page synthesizes distributor pricing, drop-in same-family alternatives, and practical design notes not found in the standalone datasheet, helping engineers source this legacy HC08 part and evaluate obsolescence risk.
Drop-in alternatives for MC68HC908JK8CDW — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MC68HC908JK8CDW (same form factor and footprint) — differing in Package, Program Memory Size, Mounting Type, EEPROM Size, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC68HC908JK3CDW
✅ Drop-In📋 Reference alternative (not in catalog)
MC68HC908JK1CDW
✅ Drop-In✓ In Stock
$4.8 / Unit
View Datasheet →MC68HC908JK3ECDW
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MC68HC908JL3ECDW
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$4.85 / Unit
View Datasheet →MC68HC908JK8CP
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MC68HC908JK8CDW Maximum Ratings & Electrical Characteristics
| Core Processor | HC08 |
| Core Size | 8-bit |
| Max Bus Frequency | 8 MHz |
| Program Memory Size | 8 KB (8K x 8) FLASH |
| RAM Size | 256 x 8 (256 bytes) |
| EEPROM Size | None (not present per datasheet summary) |
| Number of I/O Pins | 15 |
| Connectivity | SCI (Serial Communications Interface) |
| Peripherals | LED driver, LVD, POR, PWM |
| Package | 20-pin SOIC (DW), 7.5 mm body width |
| Mounting Type | Surface Mount |
| Architecture | Von Neumann (CISC) |
| Program Memory Type | FLASH |
MC68HC908JK8CDW Pin Configuration
| Pin 1 | RST — Reset input (active low) with internal pull-up |
| Pin 2 | IRQ — External interrupt request |
| Pin 3 | PTA0 — GPIO / Keyboard interrupt |
| Pin 4 | PTA1 — GPIO / Keyboard interrupt |
| Pin 5 | PTA2 — GPIO / Keyboard interrupt |
| Pin 6 | PTA3 — GPIO / Keyboard interrupt |
| Pin 7 | PTA4 — GPIO / SCI TX |
| Pin 8 | PTA5 — GPIO / SCI RX |
| Pin 9 | PTA6 — GPIO |
| Pin 10 | PTA7 — GPIO |
| Pin 11 | PTB0 — GPIO / PWM channel |
| Pin 12 | PTB1 — GPIO / PWM channel |
| Pin 13 | PTB2 — GPIO / PWM channel |
| Pin 14 | PTB3 — GPIO / PWM channel |
| Pin 15 | PTB4 — GPIO / LED driver |
| Pin 16 | PTB5 — GPIO / LED driver |
| Pin 17 | VSS — Ground |
| Pin 18 | VDD — Positive supply voltage |
| Pin 19 | BKGD/MS — Background debug mode / Mode select |
| Pin 20 | OSC1 — Crystal oscillator input / external clock input |
Typical Applications
MC68HC908JK8CDW is suitable for 6 applications: Appliance Control Panels, LED Lighting Controllers, Remote Control Transmitters, Small Motor Control (Fans, Pumps), Security Keypads and Access Panels, Consumer Toys and Hobby Devices.
Appliance Control Panels
The MC68HC908JK8CDW's 8KB FLASH, 256-byte RAM, and 15 GPIO pins make it a fit for washing machine, microwave, and dishwasher control boards where 8-bit MCU processing at low cost is required. The integrated LVD and POR simplify reset circuit design for mains-powered appliances with noisy rails. The PWM channels drive relays, buzzers, and triac interfaces directly, while the SCI port supports UART communication to the main board or external displays. Compared to older HC05 designs the in-system FLASH plus BDM accelerates firmware iteration during product development.
Recommended
LED Lighting Controllers
The MC68HC908JK8CDW's built-in LED driver peripheral, PWM channels, and 8KB program space fit decorative and architectural LED controllers requiring smooth dimming and color-mixing logic. The 8 MHz HC08 core provides enough headroom for simple PWM table lookups and SCI-based DMX or proprietary control protocols. 256 bytes of RAM is sufficient for state-machine-based lighting effects without external memory. Designers can use the SCI port to receive DMX-512 or 0-10V analog dim commands while the PWM outputs drive MOSFET gates directly.
Recommended
Remote Control Transmitters
For IR/RF remote controls the MC68HC908JK8CDW pairs 8KB FLASH (enough for protocol stacks like RC5, NEC, or custom RF) with low power consumption and the integrated SCI for factory-test communication. The 15 GPIO scan a typical 5x3 matrix keypad while timers handle IR modulation. BDM programming enables quick SKU variants for different markets without retooling. The 20-SOIC package keeps the PCB small enough to fit inside a slim remote enclosure, and the HC08's deterministic interrupt response is appropriate for real-time IR protocols.
Recommended
Small Motor Control (Fans, Pumps)
The MC68HC908JK8CDW's PWM channels and 8-bit ADC-friendly HC08 core suit low-power BLDC or brushed-DC motor control in small fans and pumps. With 8KB of FLASH the device can hold simple sensorless commutation tables and PI control loops. The LVD ensures safe startup under partial supply, while the integrated LED driver provides status indication without external transistors. The 20-SOIC package and 8 MHz clock are adequate for 4-pole BLDC motors in small appliances and cooling fans.
Recommended
Security Keypads and Access Panels
The MC68HC908JK8CDW's 15 GPIO easily handles 4x4 keypad matrices with leftover pins for relays, buzzers, and status LEDs. FLASH programming allows secure storage of access codes and learning logic; BDM keeps the production programming simple. The integrated LVD and POR ensure correct startup after power loss in critical security applications. SCI supports Wiegand or RS-485 communication to upstream access controllers, and the HC08 deterministic interrupt latency is well-suited to debounce logic in keypad input.
Recommended
Consumer Toys and Hobby Devices
Cost-optimized consumer products such as electronic toys, novelties, and hobby trainers use the MC68HC908JK8CDW to drive a small number of LEDs, a piezo buzzer via PWM, and accept button inputs over its GPIO. FLASH-based firmware supports multiple SKUs and field upgrades. The 256-byte RAM and 8 MHz clock are well matched to state-machine firmware for these short-interaction designs. The 20-SOIC footprint and NXP's mature HC08 tool chain keep BOM and development cost low - key for sub-$10 retail pricing.
Recommended
Recommended Products Summary
Engineering reference data for MC68HC908JK8CDW — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC68HC908JK3CDW | MC68HC908JK1CDW | MC68HC908JK3ECDW | MC68HC908JL3ECDW | MC68HC908JK8CP |
|---|---|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 20-SOIC (DW) | 20-SOIC (DW) - same | 20-SOIC (DW) - same | 20-SOIC (DW) - same | 20-SOIC (DW) - same | 20-SOIC (DW) - same |
| Core | HC08 (8-bit, 8 MHz) | HC08 (8-bit, 8 MHz) | HC08 (8-bit, 8 MHz) | HC08 enhanced (8-bit, 8 MHz) | HC08 enhanced (8-bit, 8 MHz) | HC08 (8-bit, 8 MHz) |
| Program Memory (FLASH) | 8 KB | 4 KB | 1 KB | 4 KB | 4 KB (ROM/FLASH options) | 8 KB |
| RAM Size | 256 bytes | 256 bytes | 256 bytes | 256 bytes | 256 bytes | 256 bytes |
| GPIO Pins | 15 | 15 | 15 | 15 | 23 | 15 |
| Peripherals | SCI, LED, LVD, POR, PWM | SCI, LED, LVD, POR, PWM | SCI, LED, LVD, POR, PWM | SCI, LED, LVD, POR, PWM | SCI, LED, LVD, POR, PWM, ADC | SCI, LED, LVD, POR, PWM |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete / NRND | Obsolete / NRND | Obsolete |
Key Differentiators
- Largest FLASH in 20-SOIC HC08 JK/JL family (vs MC68HC908JK3CDW)
- Pin-compatible with JL3 family for migration headroom (vs MC68HC908JL3ECDW)
- FLASH-based vs OTP/EPROM-based HC05 predecessors (vs MC68HC705J1ACDW)
Design Notes
Place a 100 nF ceramic decoupling capacitor as close as possible to the VDD pin (pin 18), and add a bulk capacitor (e.g. 10 uF) near the supply rail entry. The integrated LVD requires stable supply ramp; verify rise time meets the datasheet spec to avoid spurious resets at power-up. Estimated: at 5V VDD with 8 MHz bus, typical HC08 active current is in the single-digit mA range, so 10 uF bulk is adequate for most designs.
Route the BKGD/MS (pin 19) and OSC1 (pin 20) traces short and away from noisy digital lines to preserve debug reliability and clock integrity. Keep the RESET line trace short and avoid running it parallel to switching signals. The 20-SOIC land pattern follows JEDEC MS-013 with 1.27 mm pitch; follow standard SOIC PCB layout guidelines for solder joint reliability.
Do not assume any EEPROM is present - the MC68HC908JK8 uses FLASH only. Configuration and calibration data must be stored in a reserved FLASH sector with wear-leveling if writes are frequent. The P-FLAG security bits in FLASH prevent unauthorized read-back; set them only after final firmware validation. The HC08 BDM (BKGD/MS) requires an open-drain connection per NXP/legacy Freescale toolchain documentation - use the recommended 4.7 kohm pull-up.
Compliance Information
Compliance fields marked unknown because the legacy HC908JK8 family pre-dates strict RoHS reporting on older NXP/Motorola part numbers; designers should consult the NXP material declaration or the reel label for the specific manufacturing lot. AEC-Q100 not applicable for an industrial/consumer 8-bit MCU.
