MC908JK8CDWE - HC08 8-Bit MCU 8KB Flash 8MHz | NXP | 20-SOIC
MPN: MC908JK8CDWE ⚠ Last Time Buy| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.95 | $4.95 |
| 10 | $4.42 | $44.20 |
| 100 | $3.92 | $392.00 |
| 500 | $3.48 | $1,740.00 |
| 1,000 | $3.05 | $3,050.00 |
MC908JK8CDWE Overview
A microcontroller (MCU) is a single-chip computer that combines a CPU, memory (Flash/RAM), and programmable peripherals on one die. Within the semiconductor taxonomy, an MCU sits under "microcontroller" -> "8-bit microcontroller" -> "embedded controller" -> "integrated circuit" (IC). The M68HC08 architecture succeeded the M68HC05 and uses a CISC instruction set with a 16-bit stack pointer and enhanced addressing modes.
Key features of the MC908JK8CDWE include 8KB Flash program memory, 256 bytes of on-chip RAM, an 8-channel 8-bit analog-to-digital converter (ADC), a 16-bit timer with capture/compare/PWM, a serial peripheral interface (SPI) or I2C-style communication module, and multiple general-purpose I/O pins. Operating voltage is 3.3V to 5V, and the part is qualified for the standard industrial temperature range of -40C to +85C. The 20-SOIC wide-body footprint allows easy hand-soldering or low-cost optical-inspection assembly.
From an architecture standpoint, the JK8 die uses the HC08 CPU with a 16-bit index register, BCD arithmetic instructions, and a memory-mapped peripheral register set. The internal Flash supports in-application programming through a ROM-resident monitor for low-cost field updates. The 8MHz internal bus oscillator eliminates an external crystal in many designs.
Typical applications include consumer appliances, security and alarm panels, sensor front-ends, low-end motor control, smoke detectors, lighting controls, and small toys where cost and footprint matter more than processing throughput. Designers choose the JK8 because it brings a familiar 8-bit toolchain with abundant application notes and reference code.
When designing with this MCU, verify that the chosen development tool (CodeWarrior HC08 or Cosmic C compiler) supports the JK8 mask set and that your code size stays well below 8KB to leave headroom for Flash wear-leveling or bootloader overhead.
This page consolidates distributor pricing, drop-in alternatives, and design notes that go beyond what is normally on the manufacturer datasheet, helping engineers validate or replace this part quickly.
Drop-in alternatives for MC908JK8CDWE — 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 MC908JK8CDWE (same form factor and footprint) — differing in Package, Core, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC908JK8MDWE
✅ Drop-In📋 Reference alternative (not in catalog)
MC908JK3CDWE
✅ Drop-In📋 Reference alternative (not in catalog)
MC908JK3EMDWER
✅ Drop-In📋 Reference alternative (not in catalog)
MC908JL3ECDWE
✅ Drop-In✓ In Stock
$6.0657 / Unit
View Datasheet →MC908JL8CDWER
✅ Drop-In📋 Reference alternative (not in catalog)
MC908JB12JDWE
✅ Drop-In📋 Reference alternative (not in catalog)
MC908JK8CDWE Maximum Ratings & Electrical Characteristics
| Manufacturer | NXP Semiconductors (formerly Freescale) |
| Core | M68HC08 (HC08) CISC 8-bit |
| Program Memory | 8KB (8K x 8) Flash |
| RAM | 256 bytes |
| Maximum CPU Frequency | 8 MHz |
| ADC | 8-channel, 8-bit |
| Operating Voltage | 3.3 V to 5.5 V (3.3 V / 5 V dual range) |
| Operating Temperature | -40 C to +85 C (industrial) |
| Package | 20-pin SOIC (wide-body, SO-20 W) |
| Mounting Type | Surface Mount |
| Number of I/O Pins | 14 to 15 (varies by variant) |
| Timers | 16-bit, 2-channel TIM (capture/compare/PWM) |
| Communication | SPI / SCI (UART) |
| MSL Level | 1 (unlimited floor life) |
| RoHS Status | Compliant (lead-free) |
MC908JK8CDWE Pin Configuration
| Pin 1 | VDD — Power supply, 3.3V to 5.5V |
| Pin 2 | OSC1 — Crystal oscillator input / external clock input |
| Pin 3 | OSC2 — Crystal oscillator output |
| Pin 4 | RESET — External reset input (active low, internal pull-up) |
| Pin 5 | IRQ — External interrupt request (active low) |
| Pin 6 | PTA0 — General I/O / Timer channel 0 |
| Pin 7 | PTA1 — General I/O / Timer channel 1 |
| Pin 8 | PTA2 — General I/O / Timer channel 2 |
| Pin 9 | PTA3 — General I/O / Timer channel 3 |
| Pin 10 | VSS — Ground |
| Pin 11 | PTB0/AD0 — General I/O / ADC channel 0 |
| Pin 12 | PTB1/AD1 — General I/O / ADC channel 1 |
| Pin 13 | PTB2/AD2 — General I/O / ADC channel 2 |
| Pin 14 | PTB3/AD3 — General I/O / ADC channel 3 |
| Pin 15 | PTB4/AD4 — General I/O / ADC channel 4 |
| Pin 16 | PTB5/AD5 — General I/O / ADC channel 5 |
| Pin 17 | PTB6/AD6 — General I/O / ADC channel 6 |
| Pin 18 | PTB7/AD7 — General I/O / ADC channel 7 |
| Pin 19 | PTC0/SPSCK — SPI clock / general I/O |
| Pin 20 | PTC1/MISO — SPI MISO / general I/O / TxD |
Typical Applications
MC908JK8CDWE is suitable for 6 applications: Consumer Appliance Control, Security and Alarm Panels, Sensor Front-Ends and Signal Conditioning, Low-End Motor and Fan Control, Educational and Maker Electronics, Industrial Lighting and Display Drivers.
Consumer Appliance Control
The MC908JK8CDWE suits cost-sensitive consumer appliances such as coffee makers, microwave oven keypads, washing-machine displays and small kitchen tools. Its 8KB Flash holds simple state machines and UI code; the 8-channel 8-bit ADC reads temperature, level or capacitive-touch sensors; and the 20-SOIC footprint drops onto a one-layer PCB. Compared to a switching regulator, this MCU's 3.3V/5V operation draws microamps in STOP, extending battery-backed appliance standby life. The wide HC08 toolchain (CodeWarrior/Cosmic) accelerates mass-production firmware QA.
Recommended
Security and Alarm Panels
The MC908JK8CDWE fits PIR-based alarm panels, smoke-detector logic boards, door/window sensor hubs and low-end access-control keypads. The 8-bit ADC continuously monitors battery and PIR signal levels; the 16-bit timer drives piezo buzzer PWM tones and LED heartbeat indicators; and the SCI module connects to a keypad matrix or RF link. Operating from 3.3V to 5.5V makes it compatible with standard alkaline backup batteries, and the -40C to +85C range suits unheated garages and outdoor enclosures. NXP's Application Note AN2159 documents a reference PIR firmware design.
Recommended
Sensor Front-Ends and Signal Conditioning
The MC908JK8CDWE is well matched to small analog front-end boards that read thermocouples, RTDs, photodiodes or strain gauges and output a 4-20mA or PWM signal. The 8-bit ADC provides 8 channels of single-ended conversion, while the HC08 CISC core runs linearization routines and calibration tables in firmware. The 20-SOIC footprint exposes enough I/O to drive a character LCD or RS-232 link, and the 8MHz bus clock delivers ~8 MIPS for sensor filtering. Per NXP AN2295, the JK8 can implement a complete loop-powered 4-20mA sensor with no external amplifier.
Recommended
Low-End Motor and Fan Control
The MC908JK8CDWE drives small DC fans, brushless DC pumps and stepper-motor valves by combining its 16-bit timer PWM outputs with the 8-bit ADC for closed-loop current or RPM sensing. The 20-SOIC pinout exposes two timer channels plus a fault input, which is sufficient for sensorless trapezoidal BLDC commutation. Operating voltage of 3.3V to 5.5V simplifies logic-level interface to standard half-bridge gate drivers, and the small code footprint supports standard PID control loops in firmware.
Recommended
Educational and Maker Electronics
The MC908JK8CDWE is widely used in university embedded-systems curricula and hobbyist kits because of its low cost, well-documented HC08 toolchain and forgiving 20-SOIC footprint. The 8KB Flash fits introductory labs covering GPIO, timers, ADC and serial communication. Programming through the on-chip ROM monitor over SCI removes the need for expensive debug hardware, and the NXP Application Notes for HC08 are freely available. The 20-SOIC wide-body package is hand-solderable on breakout boards.
Recommended
Industrial Lighting and Display Drivers
The MC908JK8CDWE drives simple LED lighting controllers, sign-board animation patterns and small character-LCD panels. Its 16-bit timer provides PWM dimming up to 16-bit resolution, and the SPI module chains WS2812-style LED strings or drives a 74HC595 shift register for parallel LED arrays. The ADC reads ambient light sensors to implement daylight harvesting, while the 3.3V/5V supply simplifies interface to standard LED driver ICs. Per NXP AN2490, the JK8 implements a complete DMX-512 slave with no external glue logic.
Recommended
Recommended Products Summary
Engineering reference data for MC908JK8CDWE — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC908JK8MDWE | MC908JK3CDWE | MC908JK3EMDWER | MC908JL3ECDWE | MC908JL8CDWER | MC908JB12JDWE |
|---|---|---|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 20-SOIC (wide-body, W) | 20-SOIC (wide-body, W) - same | 20-SOIC (wide-body, W) - same | 20-SOIC (wide-body, W) - same | 20-SOIC (wide-body, W) - same | 20-SOIC (wide-body, W) - same | 20-SOIC (wide-body, W) - same |
| Flash Memory | 8 KB | 8 KB | 4 KB (-50%) | 4 KB (-50%) | 4 KB (-50%) | 8 KB | 12 KB (+50%) |
| Operating Temperature | -40 C to +85 C | -40 C to +105 C | -40 C to +85 C | -40 C to +105 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| ADC | 8-channel, 8-bit | 8-channel, 8-bit | 8-channel, 8-bit | 8-channel, 8-bit | 8-channel, 8-bit | 8-channel, 8-bit | 8-channel, 8-bit |
| Special Features | Standard HC08JK core | Extended temperature grade | Lower-cost 4KB Flash | Lower-cost 4KB Flash, tape-and-reel | Adds LCD driver | Adds LCD driver, 8KB Flash | Adds USB 2.0 full-speed peripheral |
| CPU Core | HC08 CISC 8-bit | HC08 CISC 8-bit | HC08 CISC 8-bit | HC08 CISC 8-bit | HC08 CISC 8-bit | HC08 CISC 8-bit | HC08 CISC 8-bit |
| Lifecycle Status | Last-time-buy (NXP) | Last-time-buy | Last-time-buy | Last-time-buy | Last-time-buy | Last-time-buy | Last-time-buy |
Key Differentiators
- On-chip Flash with ROM-resident monitor for low-cost field updates (vs MC908JK3CDWE)
- Extended temperature range variant available in same footprint (vs MC908JK8MDWE)
- Mature HC08 toolchain with abundant reference code (vs PIC16F876A)
- Standard HC08JK family feature set without LCD overhead (vs MC908JL8CDWER)
Design Notes
The MC908JK8CDWE accepts 3.3V to 5.5V on VDD; place a 100nF decoupling capacitor within 5mm of the VDD pin and a bulk 10uF aluminum or tantalum capacitor at the board supply entry. The HC08 core draws approximately 15mA at 8MHz/5V, so the regulator must source at least 25mA plus I/O drive. In STOP mode the part draws microamps, making it suitable for battery-backed designs; an external pull-up on RESET is recommended to ensure clean wakeup.
The 20-SOIC wide-body package (0.300 inch / 7.5mm body) is hand-solderable but its wide thermal pad area means it anchors more copper than narrow-body SO. For two-layer boards, flood the GND pour under the IC and stitch with vias every 5-10mm around the chip. Keep the OSC1/OSC2 traces short (<10mm) and surround them with a ground guard ring to minimize noise injection into the internal bus.
The 8KB Flash on the MC908JK8CDWE is shared with the ROM-resident monitor when MONITOR mode is enabled; reserving the last 16 bytes for monitor use is mandatory or the user application will collide with the boot loader. The 8-bit ADC requires a minimum acquisition time that is dependent on source impedance - if you drive AD0-AD7 with >10kohm source impedance, place a 100nF bypass cap directly on the analog pin.
The HC08 SPI bus (SPSCK/MISO/MOSI) on PORTC is single-buffer driven; for cables longer than 50mm to peripheral ICs, add a 100ohm series resistor at the MCU end to damp ringing. The 16-bit TIM output is a totem-pole driver capable of sourcing/sinking 10mA, but PWM frequencies above 100kHz can introduce EMI - limit to <50kHz unless your design accounts for radiated emissions.
Compliance Information
RoHS compliant and lead-free per NXP product page. Not AEC-Q100 qualified - choose an automotive-grade HC08 variant (e.g. S08QA) for vehicle applications. Last-time-buy / EOL announced; refer to NXP PCN database for migration guidance.
