MCHLC705KJ1CDWE - 8-Bit HC05 MCU 4MHz OTP 16-SOIC | NXP
MPN: MCHLC705KJ1CDWE ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.6 | $2.60 |
| 10 | $2.34 | $23.40 |
| 100 | $2.08 | $208.00 |
| 500 | $1.94 | $970.00 |
| 1,000 | $1.87 | $1,870.00 |
MCHLC705KJ1CDWE Overview
An 8-bit microcontroller is a single-chip computer that integrates a CPU core, program memory, data RAM, I/O ports, and timing peripherals on one die, sitting at the lowest tier of the embedded processor hierarchy (MCU -> embedded processor -> processor). The Motorola/Freescale HC05 (68HC05) architecture was one of the most widely deployed 8-bit MCU families of the 1990s, using an accumulator-based core with memory-mapped I/O.
Key features of the MCHLC705KJ1CDWE include the 4 MHz HC05 core (8-bit), 1.2KB OTP program memory for firmware storage without an external memory device, 64 bytes of on-chip RAM for variables and stack use, and integrated POR/WDT functions that improve system reliability by recovering the MCU from lock-ups and brown-out conditions without external supervisor components.
Technically, the OTP variant of the HC705KJ1 allows one firmware programming cycle, in contrast to mask-ROM versions (MC68HC05KJ1) which are factory-programmed and cannot be changed after manufacture. This makes the OTP version suited to pilot runs and low-to-medium volume production where ROM mask charges are not justified.
Typical applications include small appliance control, simple consumer electronics, low-cost industrial timers, and legacy replacement boards still designed around the HC05 ecosystem.
Design consideration: because this device is obsolete per its part status and OTP memory cannot be erased, always validate firmware fully before programming, and secure spare stock or a redesign path for new designs.
This page consolidates distributor pricing, stock signals, drop-in family alternatives, and practical design notes not found in a single manufacturer datasheet.
Drop-in alternatives for MCHLC705KJ1CDWE — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC68HC05KJ1CDWE
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MC68HC705KJ1CDWE
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MC68HC705KJ1CBWE
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MCHLC705KJ1CDWE Maximum Ratings & Electrical Characteristics
| Core Processor | HC05 |
| Core Size | 8-Bit |
| Maximum Clock Speed | 4 MHz |
| Program Memory Size | 1.2KB (1.2K x 8) |
| Program Memory Type | OTP (One-Time Programmable) |
| RAM Size | 64 x 8 (64 bytes) |
| EEPROM | None |
| Number of I/O | 10 |
| Peripherals | POR, WDT |
| Connectivity | None |
| Package | 16-SOIC (0.295 in, 7.50 mm Width) |
| Mounting Type | Surface Mount |
| Series | HC05 / M68HC705KJ1 |
| Part Status | Obsolete |
MCHLC705KJ1CDWE 16-soic (0.295 in, 7.50 mm width) Pin Configuration Guide
Pin configuration for MCHLC705KJ1CDWE (16-soic (0.295 in, 7.50 mm width) package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for MCHLC705KJ1CDWE.
Refer to the datasheet for full pin configuration.
Typical Applications
MCHLC705KJ1CDWE is suitable for 6 applications: Small Appliance Control, Industrial Timers and Sequencers, Legacy Board Repair and Sustaining Engineering, Low-Cost Consumer Electronics, Battery-Powered Simple Instruments, Educational and Hobby Retrocomputing.
Small Appliance Control
The MCHLC705KJ1CDWE fits small appliance control boards - coffee makers, fans, and simple cookers - where the design needs only a handful of button inputs, LED or triac outputs, and a fixed control loop. Its 10 I/O lines cover a typical button-plus-LED matrix, the 4 MHz HC05 core handles simple timing loops in assembly, and the integrated POR and watchdog timer provide safe recovery after mains disturbances without an external supervisor IC. The 1.2KB OTP memory is ample for a state-machine firmware, and the 16-SOIC surface-mount package keeps the controller footprint small on single-sided cost-optimized PCBs. Because the memory is one-time programmable, finalize and fully test firmware before committing production units.
Recommended
Industrial Timers and Sequencers
Simple industrial timers, relay sequencers, and pump controllers benefit from the MCHLC705KJ1CDWE's deterministic 8-bit core and watchdog timer. The WDT guarantees that a firmware lock-up cannot leave a relay energized indefinitely, and the POR ensures defined startup after power interruptions common in factory environments. With 10 I/O lines the MCU drives optocoupled inputs and relay-driver outputs directly through transistor buffers, while the 64-byte RAM holds timing state and display data. The 16-SOIC package mounts on standard industrial PCBs, and the 1.2KB OTP memory stores sequencer logic in under 2KB. Estimated: at 4 MHz the core executes roughly 2 million instructions per second, sufficient for millisecond-resolution sequencing.
Recommended
Legacy Board Repair and Sustaining Engineering
The primary remaining use of the MCHLC705KJ1CDWE is repairing and sustaining legacy products designed around the 68HC705KJ1. Service organizations keep OTP stock to replace failed MCUs on discontinued boards, programming the archived firmware image once per device. Since the part is obsolete, availability depends on residual distributor and broker inventory, so sustaining engineers should buy sufficient buffer stock and archive firmware images and programming fixtures. The mask-ROM MC68HC05KJ1CDWE is only an interchangeable substitute where the fielded firmware matches the factory mask. Confirm the supply voltage and temperature grade from the family datasheet before substitution to avoid electrical mismatches.
Recommended
Low-Cost Consumer Electronics
Toys, novelty gadgets, and simple remote controls historically used HC705KJ-class MCUs because the total bill of materials stays minimal: one 16-SOIC IC, a ceramic resonator, and discrete components. The MCHLC705KJ1CDWE's 10 I/O lines directly drive LEDs, small speakers, and button arrays, while the on-chip oscillator and POR remove external reset and supervisor parts. The 1.2KB OTP memory accommodates sound-table or LED-pattern firmware typical of these products. For new consumer designs the device is not recommended given its obsolete status; flash-based MCUs offer reprogrammability and current production guarantees at comparable cost. For existing consumer products, remaining stock supports end-of-life service runs.
Recommended
Battery-Powered Simple Instruments
Basic battery-powered meters and indicators can leverage the HC705KJ1's low gate count and modest clock requirement; at 4 MHz the HC05 core completes simple measurement-and-display loops with deterministic timing. The 10 I/O lines interface an LCD driver segment bus or discrete LED bargraph, a few key inputs, and an ADC serial link if an external converter is added. The integrated POR gives predictable behavior during battery insertion, and the watchdog prevents frozen displays. Designers must verify the device's supply voltage limits and low-current modes in the family datasheet, since the verified web data for this specific OTP part did not include the Vdd range. Use the OTP memory for a fixed, fully tested calibration and display routine.
Recommended
Educational and Hobby Retrocomputing
The MCHLC705KJ1CDWE serves retrocomputing and embedded-systems education, letting students work with the classic Motorola HC05 accumulator-based architecture that influenced later 68HC08 and 68HC11 families. The 16-SOIC package prototypes easily on adapter boards, and the 1.2KB OTP memory is large enough for meaningful exercises - timers, I/O scanning, and WDT handling - while remaining small enough to study fully. Because OTP cannot be erased, classrooms should pair one erasable development device or emulator with cheaper OTP parts for final projects. Procurement should note the obsolete status and confirm stock with distributors such as DigiKey or LCSC, where the part has been listed in stock around the $1.94 level as of 2026-10-18.
Recommended
Recommended Products Summary
Engineering reference data for MCHLC705KJ1CDWE — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC68HC05KJ1CDWE | MC68HC705KJ1CDWE | MC68HC705KJ1CBWE |
|---|---|---|---|---|
| Package | 16-SOIC (7.50 mm) | 16-SOIC (7.50 mm) - same | 16-SOIC (7.50 mm) - same | 16-SOIC (7.50 mm) - same |
| Brand | NXP Semiconductors (Freescale) | NXP Semiconductors (Freescale) | NXP Semiconductors (Freescale) | NXP Semiconductors (Freescale) |
| Core | HC05 8-bit, 4 MHz | HC05 8-bit, 4 MHz | HC05 8-bit, 4 MHz | HC05 8-bit, 4 MHz |
| Program Memory | 1.2KB OTP | 1.2KB Mask ROM | 1.2KB OTP | 1.2KB OTP |
| RAM | 64 bytes | 64 bytes | 64 bytes | 64 bytes |
| I/O Count | 10 | 10 | 10 | 10 |
| Peripherals | POR, WDT | POR, WDT | POR, WDT | POR, WDT |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete |
| User Reprogrammable | Yes (one time, OTP) | No (factory mask ROM) | Yes (one time, OTP) | Yes (one time, OTP) |
Key Differentiators
- User-programmable OTP memory (vs MC68HC05KJ1CDWE)
- Self-contained reset supervision (vs Discrete-supervisor designs)
- Honest trade-off: no reprogrammability (vs Modern flash 8-bit MCUs)
Design Notes
The program memory is one-time programmable: a device programmed with an incorrect or incomplete image cannot be erased and must be discarded. Always validate the full firmware on a development device or in-circuit emulator before programming production OTP units, and archive the verified hex file with checksums. Additionally, the part is obsolete - confirm date codes and authenticity when buying from broker channels, since counterfeit HC05 parts circulate in the secondary market.
The verified web data did not include the supply voltage range for this specific OTP part (the distributor listing was truncated at the Vcc field). Historically HC05 KJ1 devices run from a nominal 5 V supply, but do not design to assumed values: download the MC68HC705KJ1 family datasheet and confirm the recommended Vdd range, maximum rating, and any brown-out behavior before layout sign-off. Add 100 nF decoupling directly at the Vdd pin and keep the reset pin properly pulled per the datasheet reset circuit.
Place the 100 nF ceramic decoupling capacitor within a few millimeters of the Vdd pin with a short return path to Vss. The HC705KJ1 family uses an on-chip oscillator - follow the datasheet-recommended crystal or ceramic resonator loading capacitors and keep the oscillator traces short and away from fast switching I/O. Reserve the programming pins' routing so a bed-of-nails or programming fixture can access them for OTP programming after assembly if required.
Compliance Information
Compliance status was not stated in the verified web data. The part predates RoHS-era manufacturing; confirm environmental compliance from NXP or the distributor before shipping into RoHS jurisdictions.
