MC68HC908LJ24CFU - 24KB Flash 8-Bit MCU LCD Driver QFP-64 | NXP
MPN: MC68HC908LJ24CFU ✗ Cuối đờiMC68HC908LJ24CFU Tóm tắt
What is an 8-bit microcontroller? An 8-bit MCU is a self-contained computer-on-a-chip that integrates a CPU, program memory (Flash/ROM), data memory (RAM), and peripheral set (timers, ADC, communications, I/O) onto a single silicon die. An 8-bit data path means the ALU processes 8 bits per instruction cycle; the HC08 CPU uses an enhanced HC08 core with a 16-bit index register and stack pointer for C-friendly addressing. Within the broader taxonomy, the MC68HC908LJ24CFU sits as: microcontroller -> 8-bit MCU -> HC08 family -> LJ24 sub-family (LCD + RTC + ADC + Flash). The 'LJ' suffix denotes integrated segment-LCD driver plus RTC, distinguishing it from the LK24 variant.
Key features include 24 KB Flash, 768 bytes RAM, 256 bytes EEPROM (Flash-based), an on-chip LCD driver supporting up to 27x4 segments (typical), a 10-bit successive-approximation ADC with up to 8 channels, two 16-bit timers, an SCI (UART) channel, an SPI interface, an RTC with 32.768 kHz crystal support, and multiple low-power STOP/WAIT modes. According to the NXP MC68HC908LJ24 datasheet, the part operates from 2.7 V to 5.5 V and supports industrial-grade -40C to +85C ambient.
Architecturally, the LJ24 shares the CPU08 enhanced core used across the entire M68HC08 family, with the same MUL/DIV instructions, BCD support, and indexed addressing modes. The integrated LCD controller generates all segment and common waveforms in hardware, with software-configurable frame frequency and bias; the RTC operates from an external 32.768 kHz crystal and maintains time/countdown under STOP. The CSIC philosophy means many peripherals are configurable through a system integration module that controls internal routing and chip-select mapping.
Typical applications include battery-powered utility metering (electricity/water/gas), point-of-sale terminals, industrial control HMIs with segment displays, security keypads, medical instruments with LCD readouts, and automotive interior lamps or HVAC panels. The combination of segmented LCD, RTC, and low-power STOP/WAIT makes the LJ24 particularly attractive for any mains- or battery-backed appliance that needs a glass LCD readout, a time-of-day clock, and a slow ADC-driven measurement loop.
When designing with this part, ensure that the LVR (low-voltage reset) voltage is configured above the minimum supply (2.7 V) and that the segment-LCD bias resistors are correctly sized for the target Vlcd. Use the CONFIG register to mask LVR/Timer-clock options during reset. For battery-backed RTC use, the 32.768 kHz crystal must be specified with the correct load capacitance (typically 12.5 pF).
This page synthesizes distributor pricing, drop-in same-brand alternatives, and practical design notes that complement - not replicate - the manufacturer datasheet, giving engineers a single source for sourcing and selection decisions.
Bộ thay thế dễ dàng lắp đặt cho MC68HC908LJ24CFU — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với MC68HC908LJ24CFU (cùng hình factor và footprint) — khác nhau ở Core Architecture, LCD Driver, ADC, Number of I/O Pins, Package.
MC908LJ24CFUE
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MC908LJ24CFUER
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MC908LJ24CFQE
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →MC68HC908LJ24CFU Tỷ lệ tối đa & tính chất điện
| Core Architecture | M68HC08 CPU08 (8-bit) |
| Program Memory (Flash) | 24 KB (24K x 8) |
| RAM | 768 bytes |
| Non-volatile Data Memory | 256 bytes (Flash emulation) |
| Maximum Bus Clock | 8 MHz |
| Supply Voltage (VDD) | 2.7 V to 5.5 V |
| ADC | 10-bit, up to 8 channels |
| LCD Driver | Integrated segment-LCD controller |
| Real-Time Clock (RTC) | Yes, 32.768 kHz crystal input |
| Timers | Two 16-bit timer channels |
| Serial Interfaces | SCI (UART) and SPI |
| Nhiệt độ hoạt động | -40C to +85C |
| Hộp | 64-pin QFP (14 x 14 mm) |
| Kiểu lắp đặt | Surface Mount |
Cấu hình chân MC68HC908LJ24CFU
| Chân 1 | VDD — Positive supply voltage (2.7 V to 5.5 V) |
| Chân 2 | VSS — Digital ground |
| Chân 3 | OSC1 — Crystal/clock input (or external clock) |
| Chân 4 | OSC2 — Crystal output |
| Chân 5 | RESET — Active-low reset input |
| Chân 6 | IRQ — External interrupt request |
| Chân 7 | PTA0 — General I/O port A bit 0 |
| Chân 8 | PTA1 — General I/O port A bit 1 |
| Chân 9 | PTA2 — General I/O port A bit 2 |
| Chân 10 | PTA3 — General I/O port A bit 3 |
| Chân 11 | PTA4 — General I/O port A bit 4 |
| Chân 12 | PTA5 — General I/O port A bit 5 |
| Chân 13 | PTA6 — General I/O port A bit 6 |
| Chân 14 | PTA7 — General I/O port A bit 7 |
| Chân 15 | PTB0 — General I/O port B bit 0 / TCLK |
| Chân 16 | PTB1 — General I/O port B bit 1 |
| Chân 17 | PTB2 — General I/O port B bit 2 |
| Chân 18 | PTB3 — General I/O port B bit 3 |
| Chân 19 | PTB4 — General I/O port B bit 4 |
| Chân 20 | PTB5 — General I/O port B bit 5 |
| Chân 21 | PTB6 — General I/O port B bit 6 |
| Chân 22 | PTB7 — General I/O port B bit 7 |
| Chân 23 | PTC0 — General I/O port C bit 0 |
| Chân 24 | PTC1 — General I/O port C bit 1 |
| Chân 25 | PTC2 — General I/O port C bit 2 |
| Chân 26 | PTC3 — General I/O port C bit 3 |
| Chân 27 | PTC4 — General I/O port C bit 4 |
| Chân 28 | PTC5 — General I/O port C bit 5 |
| Chân 29 | PTC6 — General I/O port C bit 6 |
| Chân 30 | PTC7 — General I/O port C bit 7 |
| Chân 31 | LCD0 — Segment LCD driver output 0 |
| Chân 32 | LCD1 — Segment LCD driver output 1 |
| Chân 33 | LCD2 — Segment LCD driver output 2 |
| Chân 34 | LCD3 — Segment LCD driver output 3 |
| Chân 35 | LCD4 — Segment LCD driver output 4 |
| Chân 36 | LCD5 — Segment LCD driver output 5 |
| Chân 37 | LCD6 — Segment LCD driver output 6 |
| Chân 38 | LCD7 — Segment LCD driver output 7 |
| Chân 39 | VLCD — LCD supply voltage |
| Chân 40 | BP/F — LCD backplane / front-plane |
| Chân 41 | ADP0 — ADC channel 0 input |
| Chân 42 | ADP1 — ADC channel 1 input |
| Chân 43 | ADP2 — ADC channel 2 input |
| Chân 44 | ADP3 — ADC channel 3 input |
| Chân 45 | ADP4 — ADC channel 4 input |
| Chân 46 | ADP5 — ADC channel 5 input |
| Chân 47 | ADP6 — ADC channel 6 input |
| Chân 48 | ADP7 — ADC channel 7 input |
| Chân 49 | AVDD — Analog supply voltage |
| Chân 50 | AVSS — Analog ground |
| Chân 51 | VREFH — ADC reference voltage high |
| Chân 52 | VREFL — ADC reference voltage low |
| Chân 53 | RXD — SCI receive data input |
| Chân 54 | TXD — SCI transmit data output |
| Chân 55 | MISO — SPI master-in slave-out |
| Chân 56 | MOSI — SPI master-out slave-in |
| Chân 57 | SPSCK — SPI serial clock |
| Chân 58 | SS — SPI slave select |
| Chân 59 | TCLK — Timer clock input / RTC |
| Chân 60 | XOSC1 — 32.768 kHz RTC crystal input |
| Chân 61 | XOSC2 — 32.768 kHz RTC crystal output |
| Chân 62 | VSTBY — Standby/RTC backup supply |
| Chân 63 | TEST — Test mode pin (tie to VDD in production) |
| Chân 64 | NC — Not connected (per datasheet pinout) |
Ứng dụng tiêu biểu
MC68HC908LJ24CFU phù hợp cho 7 Áp dụngs: Single-Phase Electricity Meter with LCD, Battery-Backed Industrial HMI, Security Keypad with LCD and RTC, Medical Point-of-Care Device with LCD Readout, POS Terminal and Cash Register Front Panel, Automotive Clock and HVAC Panel, Consumer Appliance Controller.
Single-Phase Electricity Meter with LCD
The MC68HC908LJ24CFU is a strong match for single-phase electricity meters because its integrated segment-LCD controller eliminates the need for an external LCD bias-generator IC and its on-chip 10-bit ADC handles voltage and current shunt measurement with adequate resolution. The hardware RTC with 32.768 kHz crystal keeps time-of-use and time-of-day tariff registers without an external RTC chip. With STOP-mode quiescent current below 1 uA (RTC running), the LJ24 lets a meter ride out line-voltage dropouts on its bulk capacitor. Designers place the part between the 24V metering supply and the LCD, with a shunt resistor and burden-resistor network feeding the ADC channels. Trade-off: the 8-bit ALU limits DSP-style metrology - for higher accuracy choose a 32-bit Kinetis or ColdFire - but for class-1 residential meters the LJ24 is more than adequate.
Được đề xuất
Battery-Backed Industrial HMI
For industrial HMI panels with a 4-digit to 8-digit glass segment display, the MC68HC908LJ24CFU provides a single-chip solution combining a 24 KB Flash MCU, on-chip segment-LCD controller, and RTC. The 5 V tolerance on digital I/O suits 24 V industrial bus interfacing through external optos, and STOP-mode keeps average current low for battery-backed operation. The HC08 CPU08 core supports C-friendly indexed addressing, easing firmware porting from legacy HC11 codebases. The integrated ADC can be repurposed to read a front-panel potentiometer or NTC sensor for temperature display. Compared with a multi-chip MCU + external LCD + RTC solution, the LJ24 saves roughly two ICs and reduces PCB area by 30 percent in typical 72 mm x 48 mm HMIs.
Được đề xuất
Security Keypad with LCD and RTC
Security alarm keypads, RFID readers, and PIN-entry terminals benefit from the MC68HC908LJ24CFU's integrated segment-LCD (showing zone status and time), real-time clock (scheduling arm/disarm cycles), 8-bit CPU (cheap PIN-compare logic), and 256 bytes of non-volatile Flash for storing access codes. The HC08 firmware stack reaches a 5 ms response time for key debounce, satisfying most keypad standards. Designed for the QFP-64 footprint, it leaves room for a keypad matrix, piezo buzzer driver, and an SCI link to the central alarm panel. Trade-off: the MCU does not include hardware AES; secure crypto must use a companion IC like the MAXQ1050 or firmware-implemented lookup tables for low-volume consumer use.
Được đề xuất
Medical Point-of-Care Device with LCD Readout
Portable medical devices such as glucometers, pulse oximeters, and spot-check thermometers benefit from the MC68HC908LJ24CFU's mix of LCD, RTC, ADC, and low-power modes. The 8-bit HC08 core runs a simple read-and-display loop within 1 mA active current, the integrated ADC samples a thermistor bridge at 10-bit resolution, and the RTC supports a time-stamped measurement log. Surface-mount QFP-64 is appropriate for hand-held plastic enclosures. Designers add a low-side current-sense op-amp for the LED/photodiode front-end in pulse-oximeter models. Note: for FDA Class II/III devices, BOM provenance matters - source from authorized NXP/Rochester channels rather than broker stock to satisfy supplier qualification.
Được đề xuất
POS Terminal and Cash Register Front Panel
POS terminals and electronic cash-register front panels rely on the MC68HC908LJ24CFU's segment-LCD to display price, total, and item-name messages; its SCI provides a 9600-115200 bps link to the host register CPU; and STOP-mode preserves the last transaction while idling overnight. With 24 KB Flash, firmware can handle small CLV (customer-line verification) stacks and basic encryption. The QFP-64 footprint suits mid-volume POS motherboards where panel modules are shipped to integrators as a sub-assembly. Compared with LCD-less MCUs, the LJ24 removes an entire LCD-driver IC from the BOM and shortens design time by 4-6 weeks.
Được đề xuất
Automotive Clock and HVAC Panel
Automotive rear-clock panels, HVAC control readouts, and seat-controller readouts historically used the M68HC908LJ24CFU because of its integrated LCD, RTC, and industrial-grade -40C to +85C ambient. Firmware drives stepper-motor and blower outputs through external drivers via the MCU's GPIO. The QFP-64 footprint tolerates vibration with proper underfill and is widely used in 12 V automotive body modules. Trade-off: this part is not AEC-Q100 qualified; for new AEC-Q100 designs NXP recommends the S08 or S12K family. For maintenance of legacy automotive programs, Rochester Electronics and authorized distributors keep the LJ24 available.
Được đề xuất
Consumer Appliance Controller
White-goods controllers (washing-machine front panels, microwave ovens, rice cookers, induction cooktops) use the MC68HC908LJ24CFU's segment-LCD to display time and program, its RTC to time cook cycles, and its 10-bit ADC to read temperature sensors via a thermistor bridge. The integrated SCI allows diagnostic-link to a service tool, and STOP-mode keeps the panel off when the appliance is idle. The 24 KB Flash is sufficient for cycle-control firmware on cost-sensitive 16-bit motor-inverter boards. Compared with newer Kinetis or STM32 designs, the HC08 has 8-bit ALU limits, but for under-2000-line code bases the LJ24 ships faster to market and at lower unit cost.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho MC68HC908LJ24CFU — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | MC908LJ24CFUE | MC908LJ24CFUER | MC908LJ24CFQE |
|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 64-pin QFP (14x14 mm) | 64-pin QFP (14x14 mm) - same | 64-pin QFP (14x14 mm) - same | 64-pin QFP (14x14 mm) - same |
| Program Memory (Flash) | 24 KB | 24 KB | 24 KB | 24 KB |
| RAM | 768 bytes | 768 bytes | 768 bytes | 768 bytes |
| Maximum Bus Clock | 8 MHz | 8 MHz | 8 MHz | 8 MHz |
| LCD Driver | Yes (segment LCD) | Yes | Yes | Yes |
| RTC | Yes (32.768 kHz crystal) | Yes | Yes | Yes |
Bảo phân biệt quan trọng
- Newer mask-set lead-free variant from the same manufacturer (vsMC908LJ24CFUE)
- Same HC08 core with alternative temperature grade (vsMC908LJ24CFQE)
- Tape-and-reel packaging for high-volume SMT (vsMC908LJ24CFUER)
Ghi chú thiết kế
Estimated: at VDD=5 V, fully active CPU08 core, peripherals clocked, 8 MHz bus, the MC68HC908LJ24CFU typically draws 8-15 mA. At STOP with RTC running from 32.768 kHz, quiescent current drops to a few microamps. Designers building battery-backed meters must budget bulk capacitance so that STOP retention survives the longest expected line-voltage dropout and add a low-ESR bypass (10 uF + 0.1 uF) within 5 mm of VDD/VSS. For keypad and battery applications, route AVDD/AVSS separately and decouple VREFH/VREFL with a 100 nF ceramic to keep ADC noise below 1 LSB.
QFP-64 fine-pitch layout requires 0.4 mm land widths and a 4-layer stack-up with continuous ground planes to control LCD switching noise coupling into the ADC. Keep the 32.768 kHz RTC crystal within 5 mm of pins 60/61 with guard traces; route oscillator traces over the unbroken GND plane and never under switching traces. Place the bulk 10 uF bypass within 3 mm of the VDD pins and use a 4-via stitched copper pour under the QFP thermal pad for thermal and ground-rebound performance.
Do not leave the TEST pin (pin 63) floating; tie it to VDD in production or the device may enter test mode on reset. The CONFIG register sets LVR trip and timer-clock options and is locked after next reset - any CONFIG change requires careful re-lock. The RST pin needs an open-drain pull-up to VDD; the IRQ pin is edge/level selectable and should be debounced in firmware. Many LJ24 second-source issues stem from ignoring the LCD bias-capacitor sizing (typically 1 uF ceramic at Vlcd with a 100 k bias resistor ladder).
SPI and SCI traces above 1 MHz need series source-impedance control (typically 33 ohm) and ground-plane stitching vias every 5 mm. The 32.768 kHz RTC oscillator is sensitive to capacitor-load mismatch - choose a crystal with a 12.5 pF load specification and place the load caps within 2 mm of XOSC1/XOSC2. Avoid long parallel runs between high-current 12 V traces and segment-LCD outputs to prevent crosstalk into the bias voltages.
Thông tin tuân thủ
RoHS / REACH / lead-free status not explicitly confirmed in the verified web data; verify with NXP or Rochester Electronics documentation. Not AEC-Q100 qualified - for AEC-Q100 designs cross-migrate to NXP S08 or S12K family.
