MC68HC908LJ12CFB - 8-bit HC08 MCU, 12KB FLASH, 52-LQFP | NXP
MPN: MC68HC908LJ12CFB ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9.8 | $9.80 |
| 10 | $8.65 | $86.50 |
| 100 | $7.1 | $710.00 |
| 500 | $5.95 | $2,975.00 |
| 1,000 | $5.2 | $5,200.00 |
MC68HC908LJ12CFB Overview
An HC08 microcontroller is a high-performance 8-bit MCU family that evolved from the earlier M68HC05 architecture, adding a broader instruction set, faster execution, and a more memory-rich program model. Within the broader taxonomy it sits as: microcontroller -> 8-bit MCU -> HC08 family -> M68K lineage -> embedded control IC. The 68HC908LJ12 specifically targets applications that benefit from on-chip LCD drive and a small ADC, which is why the part is widely used in metrology, instrumentation, appliance control, and consumer display electronics.
Key features of the MC68HC908LJ12CFB include 20 general-purpose I/O pins, an integrated LCD driver sized to support typical segment displays used in handheld instrumentation, brownout (LVD) and power-on reset (POR), and user-selectable internal oscillator modes that eliminate the need for an external crystal in many designs. Security is provided by a Flash lock mechanism that prevents unauthorized read-out of the on-chip program memory.
The CPU core is the standard HC08, executing instructions from internal Flash and supporting BCD and signed arithmetic operations useful for sensor readout and display handling. Memory is organized as 12KB Flash for code and a 512-byte RAM for scratchpad data, while configuration bytes in the Flash array set clock source, oscillator trimming, and security lock. The integrated 10-bit ADC with multiple input channels allows direct digitization of analog signals such as battery voltage or sensor outputs.
Typical applications include portable instruments with LCD readout, thermostats and HVAC controls, appliance user interfaces, low-cost remote-control units, and consumer products that benefit from internal LCD drive combined with HC08 software reuse. Connectivity peripherals (SPI, IRSCI) allow easy links to companion RF, sensor, or display driver chips.
When designing with this part, confirm oscillator mode settings against the actual system clock used at start-up, since the internal oscillator trimming register directly affects timing-critical peripherals. Always check Flash lock bits before programming production units, because incorrect lock configuration can lock out further in-system programming.
This page consolidates distributor pricing, drop-in alternatives within the HC08 family, and practical design notes that complement the manufacturer datasheet MC68HC908LJ12 (Freescale technical data).
Drop-in alternatives for MC68HC908LJ12CFB — 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 MC68HC908LJ12CFB (same form factor and footprint) — differing in ADC, Package, Connectivity, Core Architecture, Peripherals.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC68HC908LJ24CFB
✅ Drop-In📋 Reference alternative (not in catalog)
MC68HC908LJ24CFU
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →MC68HC908LJ12CFB Maximum Ratings & Electrical Characteristics
| Core Processor | HC08 |
| Core Size | 8-bit |
| Maximum CPU Clock | 8 MHz |
| Program Memory Size | 12 KB (12K x 8) FLASH |
| RAM Size | 512 bytes |
| Number of I/O Pins | 20 |
| Package Type | 52-TQFP (10x10 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature Range | -40C to +85C |
| Connectivity | IRSCI, SPI |
| Peripherals | LCD driver, LVD, POR, PWM (2 channels) |
| ADC | 10-bit, multiple channels |
| Internal Oscillator | Yes |
| Series | HC08 |
MC68HC908LJ12CFB Pin Configuration
| Pin 1 | PTE0/RxD — GPIO / SCI receive |
| Pin 2 | PTE1/TxD — GPIO / SCI transmit |
| Pin 3 | PTE2 — GPIO |
| Pin 4 | PTE3 — GPIO |
| Pin 5 | PTE4 — GPIO |
| Pin 6 | PTE5 — GPIO |
| Pin 7 | PTE6 — GPIO |
| Pin 8 | PTE7 — GPIO |
| Pin 9 | VDD — Power supply |
| Pin 10 | VSS — Ground |
| Pin 11 | PTA0 — GPIO |
| Pin 12 | PTA1 — GPIO |
| Pin 13 | PTA2 — GPIO |
| Pin 14 | PTA3 — GPIO |
| Pin 15 | PTA4 — GPIO |
| Pin 16 | PTA5 — GPIO |
| Pin 17 | PTA6 — GPIO |
| Pin 18 | PTA7 — GPIO |
| Pin 19 | PTB0 — GPIO / external interrupt |
| Pin 20 | PTB1 — GPIO / external interrupt |
| Pin 21 | PTB2 — GPIO / external interrupt |
| Pin 22 | PTB3 — GPIO / external interrupt |
| Pin 23 | PTB4 — GPIO / external interrupt |
| Pin 24 | PTB5 — GPIO / external interrupt |
| Pin 25 | PTB6 — GPIO / external interrupt |
| Pin 26 | PTB7 — GPIO / external interrupt |
| Pin 27 | PTC0 — GPIO / ADC |
| Pin 28 | PTC1 — GPIO / ADC |
| Pin 29 | PTC2 — GPIO / ADC |
| Pin 30 | PTC3 — GPIO / ADC |
| Pin 31 | PTC4 — GPIO / ADC |
| Pin 32 | PTC5 — GPIO / ADC |
| Pin 33 | PTC6 — GPIO / ADC |
| Pin 34 | PTC7 — GPIO / ADC |
| Pin 35 | PTD0/MOSI — GPIO / SPI MOSI |
| Pin 36 | PTD1/MISO — GPIO / SPI MISO |
| Pin 37 | PTD2/SPSCK — GPIO / SPI clock |
| Pin 38 | PTD3/SS — GPIO / SPI slave select |
| Pin 39 | PTD4 — GPIO |
| Pin 40 | PTD5 — GPIO / PWM |
| Pin 41 | PTD6 — GPIO / PWM |
| Pin 42 | PTD7 — GPIO |
| Pin 43 | LCD1 — LCD segment drive |
| Pin 44 | LCD2 — LCD segment drive |
| Pin 45 | LCD3 — LCD segment drive |
| Pin 46 | LCD4 — LCD segment drive |
| Pin 47 | LCD5 — LCD segment drive |
| Pin 48 | LCD6 — LCD segment drive |
| Pin 49 | LCD7 — LCD segment drive |
| Pin 50 | LCD8 — LCD segment drive |
| Pin 51 | OSC1 — Crystal/clock input |
| Pin 52 | OSC2 — Crystal/clock output |
Typical Applications
MC68HC908LJ12CFB is suitable for 7 applications: Handheld Digital Multimeters with LCD, Programmable Thermostats and HVAC Controls, Consumer Appliance User Interfaces, IR Remote Controls with LCD Status, Portable Battery-Powered Instrumentation, Industrial Sensor Front-End Modules, Low-Cost Educational Microcontroller Kits.
Handheld Digital Multimeters with LCD
Why MC68HC908LJ12CFB fits: the integrated segment LCD driver and 10-bit ADC let a handheld DMM display resistance, voltage, and current measurements directly without an external LCD controller. The HC08 8-bit core runs the range-switching logic and auto-ranging firmware, while the on-chip 12KB Flash holds the calibration tables needed for 3.5-digit accuracy. Design pattern: place a precision shunt resistor on one ADC channel and a resistive divider on another; the MCU reads the ADC, converts, and drives the LCD segments via internal charge pump. Trade-off: only 512 bytes of RAM limits on-screen history, so engineers typically store only the live reading and one min/max. Performance gain: one MCU replaces what previously needed a separate driver IC plus a secondary microcontroller, cutting BOM cost by ~30% and shrinking the PCB.
Recommended
Programmable Thermostats and HVAC Controls
Why MC68HC908LJ12CFB fits: HVAC user interfaces need a low-cost MCU that can drive an LCD, read analog temperature sensors, and switch relays via PWM, all of which the LJ12 integrates. The HC08's robust instruction set handles BCD math for setpoint arithmetic and signed comparisons for hysteresis. Circuit role: the ADC reads a 10k NTC thermistor divider, the CPU computes the temperature, and the LCD shows the setpoint; a PWM output drives a triac gate for a 24 VAC load. Trade-off: only two PWM channels mean multistage HVAC systems need either an external PWM expander or a bigger LJ24-family pin-compatible upgrade. Performance gain: integrating LCD + ADC + PWM in one IC eliminates the cost of three discrete chips in a basic 1H/1C thermostat.
Recommended
Consumer Appliance User Interfaces
Why MC68HC908LJ12CFB fits: white-goods appliances (microwaves, washing machines, induction cookers) need an MCU that handles front-panel buttons, drives an LCD or 7-segment display, and pulses the buzzer and timer load. The LJ12's 20 GPIO and on-chip LCD driver are sized precisely for a mid-size appliance fascia. Application: the MCU decodes a matrix keypad, runs a state machine for cooking profiles, drives the LCD time/temperature, and toggles triacs via PWM; the IRSCI port supports an optional remote-control receiver. Trade-off: the SPI can talk to external EEPROM for storing user presets but at 8 MHz the bus is rate-limited. Performance gain: integrating keypad scanning, display drive, and triac control on a single 8-bit MCU reduces front-panel board cost vs designs using separate display-driver ICs.
Recommended
IR Remote Controls with LCD Status
Why MC68HC908LJ12CFB fits: the IRSCI peripheral provides hardware infrared transmit/receive, and the SPI can talk to an external RF transceiver for two-way remote designs. With the LCD driver the remote can show channel, volume, and menu state - features normally locked out by simpler 4-bit MCUs. Application pattern: pressing a button triggers an IRSCI transmit frame, while a 1.5V coin-cell powers the device through the ADC monitoring channel. Trade-off: the internal oscillator has limited accuracy, so BLE/RF users may still need a 32 kHz crystal for sub-second timing. Performance gain: the integrated IRSCI saves an external UART-to-IR convert IC and reduces standby current by offloading bit-banging tasks to hardware.
Recommended
Portable Battery-Powered Instrumentation
Why MC68HC908LJ12CFB fits: the HC08 LJ family runs at low VDD with several STOP/WAIT low-power modes that extend battery life in portable meters and field instruments. The integrated LCD driver keeps the display active while the CPU is halted. Circuit role: a 3V lithium cell powers the MCU; the ADC monitors cell voltage while the LCD shows measurements; the MCU returns to a STOP mode between samples. Trade-off: the LJ12 has no dedicated RTC, so timekeeping must be derived from a software loop or external 32 kHz crystal. Performance gain: combined LCD + ADC + low-power modes achieve weeks of operation on a single CR2032 - very useful for portable calibrators and field loggers.
Recommended
Industrial Sensor Front-End Modules
Why MC68HC908LJ12CFB fits: industrial sensors with local displays (pressure transducers, flow meters) often need an MCU that reads the sensor, displays the value on an LCD, and supports an SPI link to a higher-level controller. The 20 GPIO and integrated peripherals are sized exactly for this kind of smart-sensor module. Application: an external pressure sensor signal is amplified and read by the 10-bit ADC, the MCU converts it to engineering units, displays the result on the LCD, and pushes a digital reading over SPI to a PLC. Trade-off: 8 MHz bus limits how fast the SPI master can poll, which can constrain update rates to ~1 kHz. Performance gain: a single HC908 LJ replaces a 4-chip analog signal-conditioner plus display-and-serial module, which is the standard 4-20 mA industrial building block.
Recommended
Low-Cost Educational Microcontroller Kits
Why MC68HC908LJ12CFB fits: HC08 was historically the workhorse of university and hobbyist embedded-system curricula, and many CodeWarrior-based labs target the LJ family. The LJ12's integrated peripherals give students hands-on exposure to ADC, PWM, LCD, and SCI in a single package. Application: students wire the development board to a sensor, write C/assembly firmware, flash via BDM, and read back results on the LCD. Trade-off: the modern MCUXpresso and S08/S12 lines have eclipsed HC08 for greenfield designs; HC08 kits mainly preserve legacy training value. Performance gain: the integrated LCD + ADC + PWM avoids the cost of buying separate breakout boards, which makes HC08 starter kits substantially cheaper than ARM Cortex kits.
Recommended
Recommended Products Summary
Engineering reference data for MC68HC908LJ12CFB — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC68HC908LJ24CFB | MC68HC908LJ24CFU |
|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 52-LQFP (10x10 mm) | 52-LQFP (10x10 mm) - same | 52-LQFP (10x10 mm) - same |
| Core / Family | HC08 / LJ family | HC08 / LJ family | HC08 / LJ family |
| Program Flash | 12 KB | 24 KB | 24 KB |
| RAM Size | 512 bytes | 512 bytes | 512 bytes |
| Maximum CPU Clock | 8 MHz | 8 MHz | 8 MHz |
| Number of I/O | 20 | 20 | 20 |
| Peripherals | LCD, ADC, PWM, SPI, IRSCI, LVD, POR | LCD, ADC, PWM, SPI, IRSCI, LVD, POR - same | Same as LJ24 CFB |
| Lifecycle Status | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Integrated segment LCD driver on-chip (vs MC68HC908JB8JDWE (no LCD, USB-only))
- Pin-compatible upgrade path within LJ family (vs MC68HC908LJ24CFB)
- On-chip 10-bit ADC with multiple channels (vs MC9S08SH4MFK (10-bit ADC, fewer channels))
- Bipolar HC08 stability over extended temperature (vs MC9S08QG8CFFE (CMOS low-power focus))
Design Notes
Estimated: at 8 MHz internal bus and 3.3V VDD, the HC08 LJ12 draws roughly 5-8 mA active and ~10 uA in STOP mode with the LCD enabled. Add a 1 uF decoupling capacitor on VDD within 25 mm of the IC, plus a 100 nF bypass on the analog VDD pin if used. If STOP-mode current must drop below 5 uA, disable the LCD charge pump explicitly in the configuration register before entering STOP. Power-on reset (POR) and LVD should be left enabled in production designs to prevent code runaway on brownout.
Use a 4-layer PCB with a continuous ground plane under the 52-LQFP; route all LCD segment lines on the same layer to minimize display-segment mismatch. Keep the OSC1/OSC2 loop area small (under 5 mm^2) when using an external crystal - the resistive feed-through path can inject noise into the LCD drivers. Provide at least 2 mm clearance between analog ADC traces and the LCD backplane signals; the LCD's common-mode voltage can alias into ADC readings during the last conversion if layout is poor.
Do not rely on the LJ12's internal oscillator for time-sensitive serial communications; the IRC trim tolerance is typically +/- 5% out of reset, and without trim adjust the SCI baud rate can drift across frame boundaries. Always load the oscillator-trim constants from a documented calibration byte in Flash before enabling the SCI. The Flash security byte must be cleared after final in-system programming or the BDM debugger will be permanently disabled - debug at first to verify, then lock.
The integrated LCD driver sources segment pins at low current (a few hundred microamps each); long traces or capacitive loads above ~30 pF will degrade the contrast duty cycle. Series resistors of 1k-10k are not usually required, but keeping segment traces short (under 75 mm) and routed away from the oscillator block improves contrast uniformity across the LCD's operating temperature range. Place a guard ring around ADC inputs on the schematic to minimize LCD cross-coupling during conversions.
Compliance Information
Compliance fields are set to 'unknown' because the verified distributor pages do not show explicit RoHS/REACH/lead-free flags. Engineers must request the latest NXP material declaration for industrial and European market products before qualification.
