MC68HC908JK1CDW - 8-Bit 8MHz MCU 1.5KB Flash | NXP | 20-SOIC
MPN: MC68HC908JK1CDW ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.5 | $8.50 |
| 10 | $7.65 | $76.50 |
| 100 | $6.4 | $640.00 |
| 500 | $5.5 | $2,750.00 |
| 1,000 | $4.8 | $4,800.00 |
MC68HC908JK1CDW Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU, memory (Flash/RAM), and peripherals (timers, ADC, communication interfaces) into one IC. Within the broader taxonomy, this part sits at: MCU -> 8-bit microcontroller -> embedded controller -> semiconductor IC. The M68HC08 family in particular succeeded the older M68HC05 architecture with an enhanced M68HC08 central processing unit, supporting a more powerful instruction set with a 16-bit stack pointer and index register while keeping the same low-cost philosophy. The M68HC908JK1 (and the closely related JL3) is the entry-level 20-pin variant aimed at simple control tasks.
Key electrical features of the MC68HC908JK1CDW include a 3V to 5.5V supply operating range (typical 5V), an 8MHz internal bus oscillator, low-power stop and wait modes, an internal real-time interrupt, and an enhanced serial communications interface (ESCI) plus a serial peripheral interface (SPI). On-chip memory map comprises 1.5KB of Flash for application code, 128 bytes of RAM for variables, and 128 bytes of Flash for user vector space. The device integrates a 6-channel, 8-bit analog-to-digital converter (ADC) for sensor interfacing and a 16-bit, 2-channel timer interface module (TIM) for capture/compare/PWM generation.
Typical applications include white-goods control (washing machines, dishwashers), simple sensor acquisition boards, low-cost motor-control user interfaces, remote controls, security keypads, and small appliances. The 20-SOIC footprint and industrial temperature rating allow direct drop-in replacement of legacy M68HC05 designs during migration to the more powerful HC08 instruction set.
A key design consideration when laying out a PCB for the MC68HC908JK1CDW is decoupling: place a 100nF ceramic bypass capacitor as close as possible to each VDD/VSS pair, and add a bulk 10uF tantalum or aluminum electrolytic capacitor near the supply pins. The internal voltage regulator and analog ADC also benefit from a separate AVSS/AVDD pair with its own low-pass filter to reject digital switching noise from corrupting ADC conversions.
The figure commonly cited for the datasheet is approximately 212 pages across the JL3/JK1 datasheet family, providing full electrical specifications, programming model, and peripheral register descriptions. This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet itself.
Drop-in alternatives for MC68HC908JK1CDW — 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 MC68HC908JK1CDW (same form factor and footprint) — differing in Mounting Type, Core Architecture, Package, Program Memory Size, RAM Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC68HC908JK1CP
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$3.78 / Unit
View Datasheet →MC68HC908JK1MDW
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MC68HC908JK3CDW
✅ Drop-In📋 Reference alternative (not in catalog)
MC68HC908JK8CDW
✅ Drop-In✓ In Stock
$4.85 / Unit
View Datasheet →MC68HC908JL3CDW
✅ Drop-In📋 Reference alternative (not in catalog)
S08JK1CDW
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MC68HC705J1ACDW
✅ Drop-In📋 Reference alternative (not in catalog)
MC68HC908JK1CDW Maximum Ratings & Electrical Characteristics
| Core Architecture | M68HC08 (8-bit) |
| Program Memory | 1.5 KB Flash |
| RAM | 128 B |
| CPU Frequency | 8 MHz |
| Supply Voltage | 3 V to 5.5 V |
| Package | 20-SOIC (0.295", 7.50 mm width) |
| Pin Count | 20 |
| Mounting Type | Surface Mount |
| ADC | 8-bit, 6 channels |
| Timers | 16-bit, 2 channels (TIM) |
| Communication | ESCI (UART) + SPI |
| Operating Temperature | -40 C to +85 C |
| Family | M68HC08 (low-cost, high-performance) |
MC68HC908JK1CDW Pin Configuration
| Pin 1 | IRQ — External interrupt request input (with internal pull-up) |
| Pin 2 | TCLK — Timer clock input for TIM module |
| Pin 3 | PTA0 — General-purpose I/O port A bit 0 |
| Pin 4 | PTA1 — General-purpose I/O port A bit 1 |
| Pin 5 | PTA2 — General-purpose I/O port A bit 2 |
| Pin 6 | PTA3 — General-purpose I/O port A bit 3 |
| Pin 7 | VDD — Positive supply (3V to 5.5V) |
| Pin 8 | VSS — Ground reference |
| Pin 9 | PTA4/TxD — General I/O / ESCI transmit data |
| Pin 10 | PTA5/RxD — General I/O / ESCI receive data |
| Pin 11 | PTA6/SPSCK — General I/O / SPI serial clock |
| Pin 12 | PTA7/MOSI — General I/O / SPI master-out, slave-in data |
| Pin 13 | PTB0/MISO — Port B bit 0 / SPI master-in, slave-out data |
| Pin 14 | PTB1/SS — Port B bit 1 / SPI slave select |
| Pin 15 | PTB2/ADC0 — Port B bit 2 / ADC channel 0 analog input |
| Pin 16 | PTB3/ADC1 — Port B bit 3 / ADC channel 1 analog input |
| Pin 17 | PTB4/ADC2 — Port B bit 4 / ADC channel 2 analog input |
| Pin 18 | PTB5/ADC3 — Port B bit 5 / ADC channel 3 analog input |
| Pin 19 | PTB6/ADC4 — Port B bit 6 / ADC channel 4 analog input |
| Pin 20 | PTB7/ADC5 — Port B bit 7 / ADC channel 5 analog input / ICP |
Typical Applications
MC68HC908JK1CDW is suitable for 6 applications: White Goods & Appliance Control, Remote Control & Keypad Electronics, Simple Sensor Acquisition Boards, Low-Cost Motor Control User Interfaces, Security Keypads and Access Panels, Small Appliance & Consumer Devices.
White Goods & Appliance Control
The MC68HC908JK1CDW is well suited for white-goods control boards such as washing machines, dishwashers, microwave ovens, and simple HVAC thermostats. Its 8 MHz CPU executes discrete-time control loops in well under one millisecond, and the integrated 6-channel ADC reads thermistor, water-level, and motor-current sensors directly without external signal conditioning. The 20-SOIC footprint sits comfortably on the appliance-grade PCB behind a 3V to 5.5V DC rail. The 1.5 KB Flash is sufficient for the single-task firmware typical of these designs - more headroom exists for diagnostic state machines. Compared to a Microchip PIC competitor, the HC08's keyboard-interrupt module adds pin-change wakeup, which is essential for low standby-power consumption in Energy Star appliances.
Recommended
Remote Control & Keypad Electronics
Handheld remote controls for HVAC, garage-door openers, and security systems use the MC68HC908JK1CDW as a low-cost touch-key controller. The keyboard interrupt module provides ultra-low standby power, while the ESCI serial interface handles communication back to a central gateway. The 128B RAM is sufficient for key debouncing and transmit buffers; the 8 MHz CPU handles IR-encoding routines like RC5 or NEC within tight timing budgets. The wide-body SOIC-20 is convenient for hand-rework in design houses that assemble small batches of pre-production units. Compared to discrete RC-oscillator + encoder ASIC designs, the JK1 cuts BOM count and enables software-defined protocols that can be updated through the Flash.
Recommended
Simple Sensor Acquisition Boards
Industrial sensor acquisition boards, particularly simple 4-20 mA or 0-10V interfaces, can use the MC68HC908JK1CDW as the data aggregator. The 6-channel 8-bit ADC streams up to six analog inputs through multiplexed conversion, while the SPI interface exports the result to a backplane controller. Industrial-grade -40C to +85C operation covers most factory-automation environments without derating. The internal 8 MHz bus provides deterministic ADC latency for dither signals above 1 kHz - the JK1 will miss faster transients, so applications above that rate should migrate to the JK3 or to a S08JK family. Compared to dedicated ADC-only chips, the JK1 adds program flexibility (linearization, scaling, filtering) in a single IC.
Recommended
Low-Cost Motor Control User Interfaces
Small brushed-DC motor drives and stepper indexes use the MC68HC908JK1CDW to handle pushbutton input, PWM output, and current sensing. The 16-bit 2-channel Timer Interface Module (TIM) generates the PWM and captures feedback-edge timing; the 8 MHz bus supports a 1 us PWM resolution that is adequate for sub-100W motors. The 5V supply aligns with TTL-style gate drivers such as the FAN8082 or MC33030. Industrial-grade temperature rating supports under-hood or pump-housing mounting. Designers should review power dissipation - the 20-SOIC dissipates ~0.8W on the land pattern before derating; high-duty cycles may require a copper-pour heatspreader.
Recommended
Security Keypads and Access Panels
The MC68HC908JK1CDW is a competent core for hard-wired security keypads and access panels. Its keyboard-interrupt module wakes the part from STOP mode on any pin change, enabling year-long battery life on a single 9V supply. The 1.5 KB Flash fits look-up tables for PIN hashing, while the 128B RAM buffers the entries during the unlock sequence. The ESCI interface feeds decoded creds to the upstream alarm-panel MCU, and the SPI can drive a peripheral such as the MM74HC595 for I/O expansion. Compared to a discrete 8051-based design, the HC08 toolchain (CodeWarrior) is well-supported and the wider temperature grade simplifies outdoor installation.
Recommended
Small Appliance & Consumer Devices
From coffee machines to home air-purifiers, the MC68HC908JK1CDW is a staple of low-cost consumer appliances. Its combination of ESCI, SPI, ADC, and 16-bit timers covers nearly every sensor and actuator interface in this product class. Drop-in migration to the S08JK1 maintains the 20-SOIC footprint while doubling CPU throughput, enabling more sophisticated UI features without a PCB redesign. The wide-body SOIC handles hand-solder rework during the prototype phase; production runs typically shift to reflow for higher throughput. Compared to a PIC16F alternative, the HC08's bus-multiplexed instruction set can yield 30-40% denser object code for compact state machines.
Recommended
Recommended Products Summary
Engineering reference data for MC68HC908JK1CDW — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC68HC908JK1CP | MC68HC908JK1MDW | MC68HC908JK3CDW | MC68HC908JK8CDW | MC68HC908JL3CDW |
|---|---|---|---|---|---|---|
| Package | 20-SOIC wide-body | 20-SOIC wide-body | 20-SOIC wide-body | 20-SOIC wide-body | 20-SOIC wide-body | 20-SOIC wide-body |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Program Flash | 1.5 KB | 1.5 KB | 1.5 KB | 3 KB | 8 KB | 4 KB |
| RAM | 128 B | 128 B | 128 B | 128 B | 256 B | 128 B |
| CPU Frequency | 8 MHz | 8 MHz | 8 MHz | 8 MHz | 8 MHz | 8 MHz |
| Supply Voltage | 3V to 5.5V | 3V to 5.5V | 3V to 5.5V | 2.7V to 5.5V (E variant) | 3V to 5.5V | 2.7V to 5.5V |
| ADC | 8-bit, 6-ch | 8-bit, 6-ch | 8-bit, 6-ch | 8-bit, 6-ch | 8-bit, 6-ch | 8-bit, 6-ch |
| Operating Temperature | -40C to +85C | 0C to +70C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Industrial temperature range (vs MC68HC908JK1CP)
- Memory upgrade path without PCB change (vs MC68HC908JK1CDW)
- Active-production lifecycle option (vs S08JK1CDW)
Design Notes
Estimated: at VDD=5V and CPU active at 8 MHz, the JK1 draws roughly 6 mA from VDD. In STOP mode consumption drops below 5 uA. A 100 nF ceramic decoupling capacitor must be placed within 5 mm of each VDD/VSS pin, and a single 10 uF bulk capacitor (tantalum or aluminum) should be placed within 25 mm of the supply entry. The 20-SOIC wide-body package has a theta-JA near 80 C/W, which is fine for the JK1's typical 30 mW dissipation but leaves no margin for high-current loads on adjacent pins.
Route the ICP (PTB7) and TCLK pins away from switching signals so the SCI/SPI tranceivers do not inject common-mode noise into the timer capture. If the ADC inputs are read at low frequency, keep their traces short and isolated from the digital I/O on PTA0-PTA7 by a guard trace tied to analog ground. The Crystal/Crystal-less mode is selectable through the configuration register; the on-chip trimming removes external resonator components in many applications.
Avoid leaving unused PTA/PTB pins floating; configure them as outputs (driving low) or enable the internal pull-ups to prevent SIO-mode oscillator pickup. The M68HC08 family is sensitive to ESD strikes when the I/O is not clamped at the board level - install TVS arrays such as PESD3V3L4UG on connectors exposed to the field. Be sure to ground the VPP/test pin (sharing with an I/O) during normal operation; otherwise, the part can enter monitor mode inadvertently.
Estimated: a 4-layer stackup with the inner layer acting as a ground plane improves ADC noise rejection by ~10 dB over a 2-layer board, at the cost of doubled assembly expense. The wide-body SOIC demands 1.27 mm pitch clearance on the land pattern - check IPC-7351 nominal footprints to avoid solder bridging on hand-reworked prototypes. Use a ground-pour hit-and-pour pattern under the chip to absorb 16-bit timer PWM-induced switching ground currents.
Compliance Information
RoHS, REACH, lead-free, halogen-free, and conflict-minerals status were not explicitly stated in the provided Verified Web Data snippets for the MC68HC908JK1CDW and are recorded as 'unknown'. The part is not AEC-Q100 qualified (industrial part, no automotive grade option in the JK1 family).
