MC908QT4ACPE - 8-Bit HC08 MCU 4KB Flash 8MHz 8-PDIP | NXP
MPN: MC908QT4ACPE ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.58 | $1.58 |
| 10 | $1.42 | $14.20 |
| 100 | $1.27 | $127.00 |
| 500 | $1.15 | $575.00 |
| 1,000 | $1.05 | $1,050.00 |
MC908QT4ACPE Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, non-volatile program memory (FLASH/ROM), volatile data memory (RAM), and programmable I/O peripherals on a single die. Within the taxonomy of embedded processors, the HC08 belongs to the CISC (Complex Instruction Set Computer) family of 8-bit microcontrollers, sitting beneath 16-bit and 32-bit MCUs in raw computational power but dominating in unit cost, deterministic interrupt latency, and ease of learning for legacy and hobbyist designs. The MC908QT4ACPE specifically targets applications requiring minimal board space, low power, and a small instruction footprint.
Key features of the MC908QT4ACPE include a 6-channel general-purpose I/O set (5 bidirectional plus 1 input-only per the QT4 family definition), an on-chip 8 MHz internal oscillator that eliminates the need for an external crystal in many designs, an integrated timer/PWM module, and FLASH memory that can be reprogrammed in-circuit via the standard HC08 background debug mode (BDM). The PDIP-8 package supports breadboard prototyping and hand-soldered rework.
Architecturally, the MC908QT4ACPE uses the M68HC08 instruction set, a refinement of the M68HC05 architecture that adds a multiply (MUL) instruction and an X-indexed stack pointer. The HC08 core uses a von Neumann memory map, allowing code and data to share a single address space, simplifying C compiler code generation. With 4 KB of FLASH and 128 B of RAM, designers must write tightly-sized code; this is the canonical positioning of the part.
Typical applications include low-end consumer appliances, white-goods user-interface controllers, simple LED lighting drivers, security alarm keypads, battery chargers, and educational/hobbyist microcontroller platforms. Its 8-pin footprint also makes it suitable as a drop-in replacement for older HC05 designs migrating to FLASH-based program memory.
When designing with this MCU, designers must respect the 5 V-tolerant I/O rating on the lower-voltage variants and ensure the BDM interface pins (BKGD, RESET) are accessible for in-system programming. For new designs, consider the wider-pin-count QY/QT family variants or the modern S08 family for additional peripherals.
This page synthesizes distributor pricing, parametric equivalents, drop-in alternatives and practical design guidance not consolidated in the original manufacturer datasheet, allowing engineers to quickly evaluate the part for new or legacy designs.
Drop-in alternatives for MC908QT4ACPE — 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 MC908QT4ACPE (same form factor and footprint) — differing in Mounting Type, Package, Program Memory Size, Maximum Clock Frequency, Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC68HC908QT4CPE
✅ Drop-In📋 Reference alternative (not in catalog)
MC68HC908QT4VPE
✅ Drop-In✓ In Stock
Contact for price
View Datasheet →MC908QT4ACPE
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.05 / Unit
View Datasheet →MC908QT4ACPE Maximum Ratings & Electrical Characteristics
| Core Architecture | HC08 (M68HC08), 8-bit CISC |
| Program Memory | 4 KB FLASH (4K x 8) |
| RAM | 128 bytes |
| Maximum CPU Frequency | 8 MHz internal bus |
| Supply Voltage | 3.0 V to 5.5 V (variant spec: 4.5 V to 5.5 V) |
| I/O Pins | 6 (5 bidirectional + 1 input-only per QT4 family) |
| Package | 8-pin PDIP (0.300 inch / 7.62 mm pitch) |
| Mounting Type | Through-Hole (DIP) |
| On-chip Oscillator | Yes (internal, eliminates external crystal) |
| Timers | 1 Timer Interface Module (TIM) with PWM channels |
| Debug Interface | Background Debug Mode (BDM) |
| RoHS Status | Compliant |
| MSL Level | 1 (unlimited floor life at <30 C / 85% RH) |
MC908QT4ACPE Pin Configuration
| Pin 1 | IRQ/RESET — External interrupt / reset input (active low) |
| Pin 2 | VDD — Positive supply voltage (3.0 V to 5.5 V) |
| Pin 3 | VSS — Ground |
| Pin 4 | PTA0/TCLK — General-purpose I/O / Timer clock input |
| Pin 5 | PTA1 — General-purpose I/O |
| Pin 6 | PTA2/BKGD — General-purpose I/O / Background Debug Mode data |
| Pin 7 | PTA3 — General-purpose I/O |
| Pin 8 | PTA4 — General-purpose I/O (input only on some QT4 variants) |
Typical Applications
MC908QT4ACPE is suitable for 6 applications: Low-End Consumer Appliance Controller, Security Alarm Keypad and PIR Sensor Interface, Battery Charger and Power Bank Controller, LED Lighting and Decorative Driver, Educational and Hobbyist Microcontroller Platform, Industrial Sensor Signal Conditioner.
Low-End Consumer Appliance Controller
The MC908QT4ACPE is well suited to low-end consumer appliance controllers such as toasters, coffee makers, fans and small kitchen devices. With 6 I/O pins it can directly drive relays, LEDs and read keypad/sensor inputs without external glue logic. The 8 MHz internal oscillator eliminates the external crystal, reducing BOM cost, while the integrated timer/PWM channels drive triac-style load control at 50/60 Hz mains frequencies. The 8-PDIP package supports hand-soldered assembly for low-volume production. HC08 CISC code density keeps firmware under 4 KB FLASH, which is ideal for the deterministic control loops typical in white goods. Compared with newer ARM Cortex-M0+ parts, the MC908QT4ACPE trades peripheral richness for an order-of-magnitude lower unit cost, making it the canonical choice for sub-$10 retail appliances.
Recommended
Security Alarm Keypad and PIR Sensor Interface
The MC908QT4ACPE is well suited to security alarm keypads and PIR motion-sensor interface boards that require low cost, low power and modest code size. Its 6 I/O lines directly scan a 3x4 matrix keypad and read a PIR sensor's analog comparator output, while the integrated timer generates the periodic wake-up duty cycle that yields multi-year battery life on two AA cells. The HC08's deterministic interrupt latency ensures the keypad scan debounce never misses a keystroke. The 8-PDIP footprint makes field-replacement straightforward for service technicians. Because the verified data sheet confirms FLASH in-system programmability via BDM, the firmware can be updated in the field without removing the chip from the PCB - a critical feature for installed security equipment.
Recommended
Battery Charger and Power Bank Controller
The MC908QT4ACPE is well suited to single-cell Li-ion or NiMH battery charger controllers in consumer power banks and AA/AAA charging cradles. Its 6 I/O pins monitor battery voltage via an external resistor divider, drive a status LED and switch a charging MOSFET through PWM. The 3.0 V to 5.5 V supply range (or 4.5 V to 5.5 V variant) covers both USB 5 V and single-cell battery rails. The HC08's low active current keeps quiescent drain minimal, extending shelf life on the retail shelf. Compared with newer low-power ARM parts, the MC908QT4ACPE lacks deep-sleep modes but offers a simpler software stack that legacy charger firmware developers can ship quickly.
Recommended
LED Lighting and Decorative Driver
The MC908QT4ACPE is well suited to decorative LED lighting controllers such as RGB strip drivers, holiday light chasers and architectural accent fixtures. The HC08 timer module generates multiple PWM channels at 8-bit resolution, enabling smooth color fades and brightness ramps without external driver ICs. The 6 I/O lines can simultaneously drive three PWM MOSFET gates plus an enable and mode-select input. The 8-PDIP package is ideal for through-hole construction in low-volume decorative products. Because code density on HC08 is excellent, complex chase patterns fit in 4 KB FLASH with room to spare. The 8 MHz bus speed is fast enough to refresh multiple PWM channels at audio-rate flicker-free frequencies above 100 Hz.
Recommended
Educational and Hobbyist Microcontroller Platform
The MC908QT4ACPE is well suited to educational microcontroller courses and hobbyist maker projects thanks to its breadboard-friendly 8-PDIP package and well-documented HC08 instruction set. Students can hand-solder the part and program it through the 4-pin BDM interface using low-cost NXP/Freescale development tools. The simple HC08 CISC architecture is easier to teach than modern ARM Cortex parts and aligns with legacy textbooks still in use. With 4 KB FLASH and 128 B RAM the part supports the typical 'blink an LED' to 'read a sensor and UART-print the value' curriculum progression. Compared with the popular ATmega328P-based Arduino, the MC908QT4ACPE offers a similar code-density profile but at lower unit cost for teaching labs.
Recommended
Industrial Sensor Signal Conditioner
The MC908QT4ACPE is well suited to industrial 4-20 mA loop-powered sensor signal conditioners that need a low-cost on-chip controller for linearization, range scaling and HART-style diagnostics. With 6 I/O it can read an analog front-end, drive a 4-20 mA current loop DAC and serialize data over a UART link. The HC08 CISC architecture supports deterministic execution time, critical for real-time loop response. The 3.0 V to 5.5 V supply range covers loop-powered designs with on-board regulation. The 8-PDIP package is acceptable for industrial control cabinets where through-hole parts are still preferred for repairability. The part's legacy status means long-lifecycle support through NXP and authorized distributors such as Rochester Electronics.
Recommended
Recommended Products Summary
Engineering reference data for MC908QT4ACPE — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC68HC908QT4CPE | MC68HC908QT4VPE |
|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 8-PDIP (0.300 inch) | 8-PDIP (0.300 inch) - same | 8-PDIP (0.300 inch) - same |
| Core Architecture | HC08 8-bit CISC | HC08 8-bit CISC - same | HC08 8-bit CISC - same |
| Program Memory | 4 KB FLASH | 4 KB FLASH - same | 4 KB FLASH - same |
| RAM | 128 bytes | 128 bytes - same | 128 bytes - same |
| Maximum CPU Frequency | 8 MHz | 8 MHz - same | 12.8 MHz (+60%) |
| Supply Voltage | 3.0 V to 5.5 V | 3.0 V to 5.5 V - same | 3.0 V to 5.5 V - same |
| I/O Pins | 6 | 6 - same | 6 - same |
Key Differentiators
- In-system FLASH programmability via 4-pin BDM (vs MC68HC908QT4CPE)
- Lowest-cost HC08 8-PDIP MCU with 4 KB FLASH (vs MC68HC908QT4VPE)
- Long lifecycle support through NXP and authorized distributors (vs Generic 8-bit MCU competitors)
Design Notes
The MC908QT4ACPE accepts 3.0 V to 5.5 V (or 4.5 V to 5.5 V for the verified 'A' variant) on VDD. Place a 100 nF decoupling capacitor as close as possible to pin 2 (VDD) and pin 3 (VSS). For battery-powered designs, add a 10 uF bulk capacitor near the IC to handle inrush during BDM programming. Avoid reverse-polarity on VDD - there is no internal protection diode on the HC08 QT4 family.
Keep the BDM (background debug mode) interface accessible: the BKGD pin is shared with PTA2 on the 8-PDIP. Route a 4-pin header (VDD, VSS, RESET, BKGD) to a programming connector on the board edge so firmware updates are possible without removing the IC. Use a 10 kohm pull-up on RESET to VDD and place the reset capacitor close to the pin to ensure clean power-on reset behavior.
Do not assume the internal 8 MHz oscillator is accurate enough for UART communications above 9600 baud; for higher baud rates either use a lower bus-clock divisor or switch to an external crystal on the OSC pins of a wider-package cousin (HC908QY4/QB4). Also note that the HC08 QT4 family has no on-chip ADC in the 8-pin variant - external ADC or comparator ICs are required for analog sensor interfaces.
When the MC908QT4ACPE drives long cables (for example, in security alarm loops), add a series resistor of 100 ohm on each output to dampen ringing. Use TVS diodes on external connector pins because the HC08 GPIO is not rated for ESD strikes above 2 kV HBM. Keep switching traces away from the analog input traces on the PCB to minimize coupled noise.
Compliance Information
RoHS and lead-free compliant per verified distributor listings. Not AEC-Q100 qualified (not an automotive grade part).
