MC68HC908QT4CDW - 8-bit HC08 MCU 4KB Flash 8MHz | NXP
MPN: MC68HC908QT4CDW ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.5 | $4.50 |
| 10 | $4.1 | $41.00 |
| 100 | $3.65 | $365.00 |
| 500 | $3.2 | $1,600.00 |
| 1,000 | $2.85 | $2,850.00 |
MC68HC908QT4CDW Overview
An 8-bit microcontroller (MCU) is a compact, self-contained computing element that integrates a CPU, program memory, RAM, peripherals, and I/O into a single chip. The MC68HC908QT4CDW belongs to the HC08 family — a CISC, Von Neumann architecture family of low-cost, high-performance 8-bit microcontrollers. Within the broader taxonomy, this device sits at: microcontroller -> 8-bit MCU -> HC08 family -> QY/QT sub-family -> embedded system component.
Key features include on-chip LVD (Low-Voltage Detect) and POR (Power-On Reset) peripherals, PWM output, internal oscillator (eliminating external crystal), and 4KB of in-system programmable Flash. The HC08 core uses an enhanced M68HC08 central processor with a von Neumann architecture. With 5 I/O pins available, the QT4 variant targets space-constrained applications where minimal pin count is essential.
Typical applications include low-cost consumer electronics, white goods control, automotive body electronics (non-safety), small appliances, simple sensor interfaces, and cost-sensitive industrial control. The 5V supply range suits traditional 5V system designs while the industrial temperature grade enables harsh-environment deployments.
When designing with this part, note that with only 5 I/O pins available, applications must rely heavily on peripheral functions (PWM, timers) and may need I/O expanders if more pins are required. Programming requires a compatible HC08 programmer/debugger interface. This page synthesizes distributor pricing, drop-in same-family alternatives, and practical design notes not found in the standalone datasheet.
Drop-in alternatives for MC68HC908QT4CDW — 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 MC68HC908QT4CDW (same form factor and footprint) — differing in RAM Size, Number of I/O Pins, Peripherals, Program Memory Size, ADC.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC68HC908QT2CDW
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →MC68HC908QT1CDW
✅ Drop-In📋 Reference alternative (not in catalog)
MC68HC908QY4CDWE
✅ Drop-In📋 Reference alternative (not in catalog)
MCHC908QT4MDWE
✅ Drop-In✓ In Stock
$1.65 / Unit
View Datasheet →MC68HC908QY2CDWE
✅ Drop-In📋 Reference alternative (not in catalog)
MC68HC908QT4CDW Maximum Ratings & Electrical Characteristics
| Core Processor | HC08 |
| Core Size | 8-bit |
| Maximum Clock Speed | 8 MHz |
| Program Memory Size | 4 KB (4K x 8) Flash |
| RAM Size | 128 x 8 bytes |
| Number of I/O Pins | 5 |
| Supply Voltage (Vcc/Vdd) | 5 V (typical) |
| Oscillator Type | Internal |
| Peripherals | LVD, POR, PWM |
| Package / Case | 8-SOIC (0.209 inch / 5.30 mm width) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial) |
| RoHS Status | unknown |
| Packaging | Tube |
MC68HC908QT4CDW Pin Configuration
| Pin 1 | PTA4/TCLK2/SS — I/O port A bit 4 / Timer clock / SPI SS (function multiplexed) |
| Pin 2 | PTA3/ADC3 — I/O port A bit 3 / ADC channel 3 (multiplexed) |
| Pin 3 | Vdd — Positive supply voltage (5 V typical) |
| Pin 4 | Vss — Ground reference |
| Pin 5 | PTA0/IRQ — I/O port A bit 0 / External interrupt request (multiplexed) |
| Pin 6 | PTA1/ADC1 — I/O port A bit 1 / ADC channel 1 (multiplexed) |
| Pin 7 | PTA2/ADC2 — I/O port A bit 2 / ADC channel 2 (multiplexed) |
| Pin 8 | RST — Reset input (active low) |
Typical Applications
MC68HC908QT4CDW is suitable for 6 applications: Low-cost consumer electronics controller, White goods and small appliance control, Simple sensor interface modules, Automotive body electronics (non-safety), Industrial control and timing modules, Educational and hobbyist embedded projects.
Low-cost consumer electronics controller
The MC68HC908QT4CDW fits low-cost consumer electronics controllers because its 4 KB Flash, 128 B RAM, and 5 GPIO are sufficient for simple button/switch interfaces with PWM-driven LED or buzzer outputs. Operating at 5 V from a USB or wall-adapter-derived rail, it removes the need for an external crystal via its 8 MHz internal oscillator. The 8-SOIC package enables placement on single-sided PCBs to minimize BOM and assembly cost in high-volume products.
Recommended
White goods and small appliance control
For washing machine sub-modules, microwave user interfaces, and small appliance controllers, the MC68HC908QT4CDW's industrial temperature grade (-40C to +85C), integrated LVD/POR, and PWM peripherals provide robust operation across mains-ripple environments. The 5 V supply domain suits relay and triac-driver interfaces commonly used in appliance designs. With 4 KB Flash, designers can implement timed-control state machines plus a simple UI driver without external memory.
Recommended
Simple sensor interface modules
Sensor interface modules — temperature probes, optical switches, single-channel detectors — fit the MC68HC908QT4CDW's 5 I/O and PWM profile. The internal oscillator simplifies integration into compact PCB modules where board area is constrained. Industrial-grade operation supports factory floor installation, and the Flash-based program memory supports field firmware updates via HC08 MON08-compatible tools.
Recommended
Automotive body electronics (non-safety)
Non-safety automotive body electronics — interior lighting controllers, simple door-module sub-tasks, accessory timers — historically used the MC68HC908QT4CDW. With 5 V supply tolerance and integrated LVD, it survives automotive cranking transients when paired with proper supply conditioning. The part is obsolete; for new designs use the AEC-Q100-qualified MCHC908QT4MDWE automotive variant as the drop-in pin-compatible upgrade.
Recommended
Industrial control and timing modules
Industrial timing, sequencing, and simple control tasks that do not need networking fit the MC68HC908QT4CDW's resource profile. The PWM output can drive opto-isolators, small solenoids, or LED indicators directly, while the internal 8 MHz oscillator eliminates crystal failure modes common in vibrating industrial cabinets. Industrial temperature grade operation supports factory-floor deployment in cabinets and control panels.
Recommended
Educational and hobbyist embedded projects
The MC68HC908QT4CDW is widely adopted in educational and hobbyist embedded projects because of its simple 8-SOIC footprint, exposed HC08 architecture, and rich legacy teaching material. It can be hand-soldered easily, programmed via low-cost MON08-compatible debuggers, and integrated into simple line-following robots, blinking-LED trainers, and timing experiments. The 4 KB Flash provides headroom for student projects while keeping complexity manageable.
Recommended
Recommended Products Summary
Engineering reference data for MC68HC908QT4CDW — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC68HC908QT2CDW | MC68HC908QT1CDW | MC68HC908QY4CDWE | MCHC908QT4MDWE | MC68HC908QY2CDWE |
|---|---|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 8-SOIC | 8-SOIC - same | 8-SOIC - same | 8-SOIC (extended pinout) - same family | 8-SOIC - same | 8-SOIC (extended pinout) - same family |
| Program Memory (Flash) | 4 KB | 2 KB (-50%) | 1 KB (-75%) | 4 KB (same) | 4 KB (same) | 2 KB (-50%) |
| RAM Size | 128 bytes | 128 bytes (same) | 128 bytes (same) | 128 bytes (same) | 128 bytes (same) | 128 bytes (same) |
| Number of I/O | 5 | 5 (same) | 5 (same) | 13 (+160%) | 5 (same) | 13 (+160%) |
| Core Speed | 8 MHz | 8 MHz (same) | 8 MHz (same) | 8 MHz (same) | 8 MHz (same) | 8 MHz (same) |
| Oscillator Type | Internal | Internal | Internal | Internal | Internal | Internal |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +125C (Automotive/AEC-Q100) | -40C to +85C (Industrial) |
Key Differentiators
- Larger Flash within same 8-SOIC footprint (vs MC68HC908QT2CDW)
- Pin-compatible automotive grade option exists (vs MCHC908QT4MDWE)
- Minimal pin count optimized for cost-sensitive designs (vs MC68HC908QY4CDWE)
Design Notes
Estimated: At 5 V Vdd and 8 MHz CPU clock with all 5 I/O toggling, typical active current is in the single-digit mA range. Add bulk decoupling (10 uF) near Vdd (pin 3) and a 100 nF ceramic between Vdd and Vss (pin 4) within 5 mm of the package to suppress switching transients. The integrated POR holds the device in reset until Vdd stabilizes, but ensure ramp time meets the datasheet specification.
Because the QT4 only exposes 5 I/O pins (PTA0-PTA4), several functions are multiplexed: PTA4/TCLK2/SS, PTA3/ADC3, PTA1/ADC1, PTA2/ADC2, PTA0/IRQ. Carefully plan pin allocation before layout; losing pins to peripherals can leave no general-purpose I/O available. Confirm the exact multiplex map in the HC08Q datasheet before finalizing the schematic to avoid I/O starvation on the smallest variant.
Estimated: At 5 V supply and 8 MHz, the 8-SOIC package dissipates well under 100 mW even at full activity. The industrial temperature grade (-40C to +85C) is the binding constraint; for environments up to +125C use the MCHC908QT4MDWE automotive drop-in instead. Standard SO-8 land patterns provide adequate copper for thermal relief in normal convection cooling.
Compliance Information
Compliance data not present in the verified web data extract. RoHS/REACH status should be confirmed at the orderable distributor level. AEC-Q100 qualification applies only to the automotive MCHC908QT4MDWE variant, not the standard QT4.
