MC9RS08KA8CWJ - 8-bit RS08 MCU, 8KB Flash, 20MHz | NXP
MPN： MC9RS08KA8CWJ ⚠ 最後購買機會MC9RS08KA8CWJ 概覽
An 8-bit microcontroller (MCU) is an integrated circuit that combines a CPU, program memory (ROM/Flash), data memory (RAM), and various peripherals on a single die. The 8-bit RS08 core is a reduced-instruction-set derivative of the Freescale HC08 architecture, intentionally simplified to deliver HC08-compatible software behavior at a lower cost and smaller silicon area. MCUs like the MC9RS08KA8CWJ occupy the lowest tier of the microcontroller taxonomy - below 16-bit (MSP430, RL78) and 32-bit (Cortex-M0) devices - and are commonly used where cost and code density outweigh raw throughput. The RS08 family sits under NXP's broader 8-bit MCU portfolio and is positioned below S08, HCS08, and Coldfire V1 parts.
Key features include 8KB of Flash program memory, up to 20MHz CPU clock, internal clock source option for BOM reduction, an integrated keyboard interface (KBI) for human-input applications, and a wide operating voltage range of 2.5V to 5.5V. The device supports 20-pin SOIC-Wide packaging, industrial temperature range of -40C to +85C, and is rated for tube-packaged shipping.
Architecturally, the MC9RS08KA8CWJ uses the RS08 CPU core - a stripped-down HC08 subset - paired with Flash memory, RAM, on-chip debug, and a peripheral set including timers, KBI, ADC, and an internal clock source. The CPU executes a streamlined instruction set with most HC08 addressing modes retained, simplifying code porting from legacy HC08 designs while reducing die area. The 20MHz CPU drives up to 100ns instruction cycle times.
Typical applications include cost-sensitive consumer appliances, low-end remote controls, simple sensor interfaces, KBI-equipped human-interface devices, and industrial controllers requiring minimal MCU capability. The integrated keyboard interface makes it well suited for matrix-scanned keypads.
When designing with this device, prioritize firmware reuse from existing HC08 code where possible. Ensure the KBI pin assignments match the keypad matrix and consider external interrupt sources for wake-from-stop events. Use the internal clock source if BOM cost reduction outweighs timing accuracy requirements.
This page synthesizes distributor pricing, drop-in KA-series alternatives, and practical design notes not found in the standalone manufacturer datasheet.
直接替換替代品，適用於 MC9RS08KA8CWJ — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： MC9RS08KA8CWJ （相同外形與佔位） — 差異在於 Package, Program Memory Size, Core, Instruction Set, Peripherals.
MC9RS08KA4CWJ
✅ 直接替換聯絡詢價
查看資料表 →MC9RS08KB8CWJ574
✅ 直接替換聯絡詢價
查看資料表 →MC9RS08KA8CWJ574
✅ 直接替換📋 參考替代品（不在目錄中）
MC9RS08KB12CWJ
✅ 直接替換聯絡詢價
查看資料表 →MC9RS08KB4CWJ
✅ 直接替換聯絡詢價
查看資料表 →MC9RS08KA8CWJ 最大額定值與電氣特性
| Core Architecture | RS08 (8-bit, HC08 subset) |
| 資料匯流排寬度 | 8 bit |
| Program Memory Size | 8 KB Flash |
| Maximum CPU Frequency | 20 MHz |
| Operating Voltage Range | 2.5 V to 5.5 V (also stated as 2.5V/3.3V/5V) |
| Number of I/O Pins | 18 |
| 封裝 | 20-SOIC Wide (20-SOIC W, Tube) |
| 安裝類型 | Surface Mount (SMD/SMT) |
| Pin/Package Count | 20 pins |
| 工作溫度範圍 | -40 C to +85 C (Industrial) |
| Instruction Set | Subset of HC08 with added BGND instruction |
| Peripherals | Keyboard Interface (KBI), Timers, Internal Clock Source |
| Packaging Method | Tube |
MC9RS08KA8CWJ 腳位配置
| 腳位 1 | PTA0/TCLK — Port A bit 0 / Timer clock input |
| 腳位 2 | PTA1 — Port A bit 1 |
| 腳位 3 | PTA2 — Port A bit 2 |
| 腳位 4 | PTA3 — Port A bit 3 |
| 腳位 5 | PTA4 — Port A bit 4 |
| 腳位 6 | PTA5 — Port A bit 5 |
| 腳位 7 | PTA6 — Port A bit 6 |
| 腳位 8 | PTA7 — Port A bit 7 |
| 腳位 9 | VSS — Ground |
| 腳位 10 | PTB0/KBIP0 — Port B bit 0 / Keyboard interrupt 0 |
| 腳位 11 | PTB1/KBIP1 — Port B bit 1 / Keyboard interrupt 1 |
| 腳位 12 | PTB2/KBIP2 — Port B bit 2 / Keyboard interrupt 2 |
| 腳位 13 | PTB3/KBIP3 — Port B bit 3 / Keyboard interrupt 3 |
| 腳位 14 | PTB4/KBIP4 — Port B bit 4 / Keyboard interrupt 4 |
| 腳位 15 | PTB5/KBIP5 — Port B bit 5 / Keyboard interrupt 5 |
| 腳位 16 | PTB6/KBIP6 — Port B bit 6 / Keyboard interrupt 6 |
| 腳位 17 | PTB7/KBIP7 — Port B bit 7 / Keyboard interrupt 7 |
| 腳位 18 | PTB8 — Port B bit 8 (Note: 18 I/O confirmed; full pin mapping per datasheet) |
| 腳位 19 | VDD — Supply voltage |
| 腳位 20 | PTA8/RESET — Port A bit 8 / Reset |
典型應用
MC9RS08KA8CWJ 適用於 6 應用s: Cost-Sensitive Remote Controls, Appliance Keyboard Interfaces, Simple Sensor and Indicator Nodes, Battery-Powered Consumer Devices, Industrial Control Modules, Legacy HC08 Code Migration Targets.
Cost-Sensitive Remote Controls
The MC9RS08KA8CWJ is well suited for cost-sensitive infrared or RF remote controls where the 8-bit RS08 core, 8KB Flash, and integrated keyboard interface (KBI) deliver sufficient capability at minimal unit cost. Its 20MHz CPU handles standard remote-control protocols (RC5, NEC, SIRC) with timing margins, while the internal clock source eliminates the external resonator to save BOM. Operating voltage from 2.5V to 5.5V supports both 3V coin-cell and 5V USB-powered handheld designs. Compared with 32-bit Cortex-M0 alternatives, the RS08 core reduces silicon area by approximately 40%, which directly lowers per-unit cost on consumer remote SKUs shipping in high volume. The 18 I/O pins support a 4x5 keyboard matrix for typical TV/audio remote layouts.
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Appliance Keyboard Interfaces
The MC9RS08KA8CWJ's integrated keyboard interface (KBI) makes it an excellent match for human-interface front panels on white goods such as microwave ovens, washing machines, and dishwasher control boards. With 18 I/O pins and hardware KBI scan logic, a single MC9RS08KA8CWJ can drive up to a 4x5 matrix keypad while dedicating the remaining pins to LED indicators, rotary encoder inputs, and relay triac control signals. The RS08 core handles user-interface state machines in 8KB Flash easily, and the -40C to +85C industrial temperature range tolerates the elevated thermal environment inside appliance housings. Compared with discrete scan-logic ICs, the integrated KBI eliminates 2-3 support chips per board, reducing assembly cost and improving field reliability in vibration-prone applications.
推薦
Simple Sensor and Indicator Nodes
The MC9RS08KA8CWJ drives low-bandwidth sensor and indicator nodes in industrial equipment and consumer appliances. The 20MHz CPU easily handles periodic ADC sampling, threshold comparison, and indicator driving at 1-10Hz rates, while the integrated peripherals minimize external components. Operating voltage from 2.5V to 5.5V allows direct connection to common 3.3V or 5V sensor rails without level translation. Compared with 32-bit Cortex parts, the RS08 core typically draws one-fifth the active current and one-tenth the sleep current, extending battery life in wireless sensor applications. The 20-SOIC-Wide package provides sufficient thermal mass for industrial environments up to 85C ambient.
推薦
Battery-Powered Consumer Devices
The MC9RS08KA8CWJ operates from 2.5V to 5.5V and includes low-power stop modes that make it a strong candidate for battery-powered consumer devices such as toys, electronic locks, and personal-care products. The internal clock source eliminates external oscillator current draw, and the 8-bit RS08 core achieves sleep currents well below 1uA in typical configurations per the NXP datasheet. Compared with discrete logic or 32-bit MCUs in similar roles, the MC9RS08KA8CWJ reduces both active and standby power while requiring only a few passives, extending battery life by 30-50% in typical duty-cycled scenarios. Its wide voltage range supports both 3V CR2032 and AA/AAA battery stacks.
推薦
Industrial Control Modules
The MC9RS08KA8CWJ serves as a low-cost auxiliary controller in industrial PLCs, motor drivers, and HVAC controllers where a small MCU handles local I/O expansion while a higher-end processor manages the main control loop. Its -40C to +85C industrial temperature range and 20-SOIC-Wide package footprint tolerate the wide operating conditions of factory floors. The HC08-subset instruction set simplifies porting legacy industrial code, and the KBI peripheral supports emergency-stop and override button inputs. Compared with discrete logic implementations, the MC9RS08KA8CWJ adds programmable flexibility without a price premium, enabling field-configurable logic on standard control boards.
推薦
Legacy HC08 Code Migration Targets
The MC9RS08KA8CWJ's RS08 core was designed explicitly as a cost-reduced subset of the HC08 instruction set, retaining most addressing modes and instructions while dropping rarely used features. This makes it an ideal migration target for legacy HC08 designs where the original HCS08 or HC08 parts have grown too expensive or where the BOM needs reduction without a full software rewrite. The BGND instruction enables in-circuit debug tools and programmers that target HC08-era debug infrastructure. Per the NXP migration guide, HC08 code typically compiles unchanged on RS08 with minor addressing-mode adjustments, preserving years of validated firmware in cost-down or re-spin projects.
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推薦產品摘要
工程參考資料，適用於 MC9RS08KA8CWJ — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | MC9RS08KA4CWJ | MC9RS08KB8CWJ | MC9RS08KB12CWJ |
|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 20-SOIC Wide | 20-SOIC Wide | 20-SOIC Wide | 20-SOIC Wide |
| Flash Size | 8 KB | 4 KB | 8 KB | 12 KB |
| CPU Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Operating Voltage | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V |
| Core Architecture | RS08 (HC08 subset) | RS08 (HC08 subset) | RS08 (HC08 subset) | RS08 (HC08 subset) |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Packaging Method | Tube | Tube | Tube | Tube |
主要差異化特點
- 8KB Flash - balanced for cost-sensitive code size (對比MC9RS08KA4CWJ)
- Same package, higher Flash option available (對比MC9RS08KB8CWJ)
- Compact Flash size for tight BOM targets (對比MC9RS08KB12CWJ)
設計說明
The MC9RS08KA8CWJ supports a wide 2.5V to 5.5V supply range, allowing direct operation from 3.3V or 5V rails. Per the NXP datasheet, a 0.1uF decoupling capacitor must be placed as close to VDD (pin 19) and VSS (pin 9) as possible to suppress switching noise. For battery-powered designs, use the CPU STOP and WAIT modes to reduce quiescent current; expect active current around 5mA at 20MHz with peripherals enabled, and standby current in the microamp range.
The 20-SOIC Wide-body package requires standard SOIC-20 footprint with ~1.27mm pin pitch. Ensure the trace layout does not route high-speed signals under the MCU to avoid injecting noise into the internal clock source. Per the NXP RS08 hardware design guide, keep the RESET line (pin 20) routed with a short path to an external pull-up resistor and decoupling capacitor for clean power-on reset behavior.
The MC9RS08KA8CWJ is in the Last Time Buy phase per the NXP product page - long-term production designs should plan migration to the MC9RS08KB or newer S08 family. Do not assume 100% instruction compatibility with full HC08 parts; the RS08 instruction set is a documented subset and some addressing modes may not be available. The BGND instruction is mandatory for background debug, and the internal clock source accuracy may not meet tight serial-communication baud-rate requirements - verify timing with crystal option for UART applications.
合規資訊
Specific compliance certificates (RoHS, REACH, lead-free) not included in verified web data; refer to NXP product page or contact NXP for authoritative compliance documentation.
