MC9RS08KB8CWJ574 - RS08 8-bit MCU, 8KB Flash, 20MHz | NXP
MPN: MC9RS08KB8CWJ574 ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.0047 | $1.00 |
| 10 | $0.95 | $9.50 |
| 100 | $0.89 | $89.00 |
| 500 | $0.82 | $410.00 |
| 1,000 | $0.74 | $740.00 |
MC9RS08KB8CWJ574 Overview
A microcontroller (MCU) is a single-chip processing element that combines a CPU, volatile and non-volatile memory, and a programmable peripheral set in one package. RS08 microcontrollers belong to the broader 8-bit MCU category and sit below 16-bit/32-bit MCUs in the processing-performance hierarchy; they are preferred when BOM cost, deterministic interrupt latency, and low static power are more critical than raw MIPS. The RS08KB family is purpose-built for ultra-low-cost designs and pairs the CPU with integrated analog and timer resources, removing the need for external glue logic.
Key differentiating features include the 20 MHz maximum CPU clock, 8KB of Flash for application firmware and calibration data, multiple timers and a multi-channel 10-bit ADC for analog signal acquisition, plus flexible low-power modes optimized for battery-backed operation. The wide-body SOIC-20 footprint simplifies hand-prototyping and visual inspection, while the RS08 instruction set keeps code density tight, often eliminating the need for an external EEPROM. According to the manufacturer product family description, the RS08KB family uses an efficient core to support interrupt-driven designs that save both component cost and PCB area.
Technically, the device leverages the HCS08-derived RS08 core, which is intentionally stripped of unused addressing modes to shrink silicon area and reduce leakage. Its 20 MHz bus rate, combined with single-cycle instructions in many cases, yields sufficient throughput for slow-loop control tasks such as PWM LED driving, thermostat regulation, and simple user-interface scanning. The integrated brown-out reset and watchdog extend system reliability in harsh electrical environments.
Typical applications include white-goods and small-appliance controllers, IR remote-control transmitters, low-end consumer gadgets, battery chargers, simple sensor hubs, and educational/development platforms. Designers also use the RS08KB family in industrial control panels where deterministic behavior and inexpensive replacement parts are valued.
When designing with this MCU, verify that the chosen in-circuit debugger and software toolchain (CodeWarrior or MCU Eclipse) support the RS08KB sub-family before committing to firmware development, because tool support differs across HCS08 derivatives. Ensure decoupling is placed within 5 mm of the VDD pin to suppress switching transients during Flash programming.
This page consolidates distributor pricing, drop-in compatible alternatives, and practical design notes that complement the RS08KB family datasheet and help engineers evaluate the part quickly.
Drop-in alternatives for MC9RS08KB8CWJ574 — 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 MC9RS08KB8CWJ574 (same form factor and footprint) — differing in Package, Program Memory Size, Peripherals, Core, Core Processor.
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View Datasheet →MC9S08QG4CFFE
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View Datasheet →MC9S08SH4MFK
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View Datasheet →MC9RS08KB8CWJ574 Maximum Ratings & Electrical Characteristics
| Manufacturer | NXP Semiconductors (formerly Freescale) |
| Core | RS08 (8-bit) |
| Family | RS08KB |
| Program Memory Type | Flash |
| Program Memory Size | 8 KB (8K x 8) |
| CPU Speed (Max) | 20 MHz |
| Package / Case | 20-SOIC (wide-body, 7.5 mm width) |
| Mounting Type | Surface Mount |
MC9RS08KB8CWJ574 Pin Configuration
| Pin 1 | VDDA — Analog supply voltage |
| Pin 2 | VSSA — Analog ground |
| Pin 3 | PTA0 — GPIO / peripheral function (TPM ch / IRQ) |
| Pin 4 | PTA1 — GPIO / peripheral function |
| Pin 5 | PTA2 — GPIO / peripheral function (ADC) |
| Pin 6 | PTA3 — GPIO / peripheral function (ADC) |
| Pin 7 | PTA4 — GPIO / peripheral function |
| Pin 8 | BKGD — Background Debug Mode pin |
| Pin 9 | RESET — Active-low reset input |
| Pin 10 | PTB0 — GPIO / peripheral function |
| Pin 11 | PTB1 — GPIO / peripheral function |
| Pin 12 | PTB2 — GPIO / peripheral function |
| Pin 13 | PTB3 — GPIO / peripheral function |
| Pin 14 | PTB4 — GPIO / peripheral function (TPM) |
| Pin 15 | PTB5 — GPIO / peripheral function (TPM) |
| Pin 16 | PTB6 — GPIO / peripheral function |
| Pin 17 | PTB7 — GPIO / peripheral function |
| Pin 18 | PTC0 — GPIO / peripheral function |
| Pin 19 | VDD — Digital supply voltage |
| Pin 20 | VSS — Digital ground |
Typical Applications
MC9RS08KB8CWJ574 is suitable for 6 applications: White Goods Appliance Controller, IR Remote Control Transmitter, Battery Charger / Power Tool Controller, Industrial Sensor Hub / Transmitter, Low-End Consumer Gadget (Toy / Education Kit), User Interface Panel (HMI Keypad / LED).
White Goods Appliance Controller
The MC9RS08KB8CWJ574 fits white-goods appliance control because its 20 MHz RS08 core and 8KB Flash cover thermostat loops, user-button scanning, and triac/relay drive sequencing in a single chip. The integrated ADC samples temperature or humidity sensors, while the timer/PWM module drives compressor relays and indicator LEDs at deterministic intervals. Because RS08KB code density is high, the 8KB ceiling accommodates state machines for wash cycles, oven profiles, and refrigerator defrost timing. Drop-in alternatives like the MC9RS08KB12CWJ give headroom for additional diagnostics without changing the PCB.
Recommended
IR Remote Control Transmitter
Battery-powered IR remote controls benefit from the MC9RS08KB8CWJ574's low quiescent current, RS08 deterministic interrupt response, and 8KB Flash sufficient for protocol stacks (RC5, NEC, SIRC) plus key-matrix decoding. The 20 MHz core generates accurate 38 kHz / 40 kHz / 56 kHz carrier frequencies via a Timer/PWM without external oscillators. Sleep current in the RS08KB family is well-suited for coin-cell or two-AAA operation across years of standby. Same-package variants let designers A/B test firmware images before locking the BOM.
Recommended
Battery Charger / Power Tool Controller
Lithium-ion battery charger and power-tool control boards use the MC9RS08KB8CWJ574 because the RS08 core performs cell voltage monitoring, current-loop PI control, and temperature derating with predictable timing. The 10-bit ADC reads shunt voltage and thermistor inputs, while PWM channels drive the synchronous-FET gate drivers in CC/CV regulation. 8KB Flash stores charge profile tables and fault logs without external EEPROM. Designers scaling up to brushless-motor control should evaluate the S08PT family for additional PWM and ADC channels on the same 20-pin footprint.
Recommended
Industrial Sensor Hub / Transmitter
Industrial 4-20 mA sensor hubs pair a sensing front-end with the MC9RS08KB8CWJ574 because the RS08 core linearizes sensor curves, applies temperature compensation, and transmits HART or Modbus messages via the on-chip UART. 8KB Flash stores calibration coefficients and unit conversion tables, while the SOIC-20 footprint survives -40C-to-85C industrial environments when ordered with the industrial temperature suffix. Same-footprint drops let designers transition from development to field units without redesigning the PCB.
Recommended
Low-End Consumer Gadget (Toy / Education Kit)
Consumer toys and educational electronics kits rely on the MC9RS08KB8CWJ574 because RS08KB silicon delivers enough compute for sound effects, LED animations, and motor sequencing at the lowest possible unit cost. The 20-pin SOIC allows hand-soldering at student workbenches and breadboard-friendly adapters, lowering assembly friction. 8KB Flash accommodates Bluetooth-BLE pairing stub code or simple robotics routines in STEM kits. Cross-brand ARM Cortex-M0+ alternatives are emerging, but the RS08KB still wins on absolute unit cost.
Recommended
User Interface Panel (HMI Keypad / LED)
The MC9RS08KB8CWJ574 handles keypad scanning, LED PWM dimming, and rotary-encoder decoding in low-end HMI panels, where its 20 MHz core and 8KB Flash comfortably debounce keys and run a small state machine. The 20-SOIC footprint fits the slim PCB outline of wall-mount controllers and accepts hand rework if a keypad legend needs to change late in the design cycle. Same-package variants allow designers to A/B test higher-memory layouts before locking volume production, and the BDM interface simplifies in-system firmware updates during field servicing.
Recommended
Recommended Products Summary
Engineering reference data for MC9RS08KB8CWJ574 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC9RS08KB4CWJ | MC9RS08KB12CWJ | MC9S08PT16AVWJ |
|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 20-SOIC (wide-body) | 20-SOIC (wide-body) | 20-SOIC (wide-body) | 20-SOIC (wide-body) |
| Core | RS08 (8-bit) | RS08 (8-bit) | RS08 (8-bit) | S08 (8-bit) - newer arch |
| Flash Memory | 8 KB | 4 KB | 12 KB | 16 KB |
| Max CPU Clock | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Lifecycle Status | NRND | NRND | NRND | Active |
Key Differentiators
- Lowest unit cost within NXP's 8-bit MCU portfolio with RS08 deterministic core (vs MKL02Z16VFG4)
- 20-pin SOIC wide-body package simplifies hand-soldering and breadboarding (vs MC9S08PT16AVWJ)
- 8KB Flash sweet-spot for thermostat / small-appliance firmware (vs MC9RS08KB4CWJ)
Design Notes
Place a 100 nF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 19) and a bulk 10 uF aluminum-polymer or ceramic capacitor on the same supply rail to suppress switching transients during Flash programming. The MC9RS08KB8CWJ574 draws higher inrush currents during row-program cycles that can momentarily sag a lightly decoupled supply, so do not route the analog VDD/VSS traces through long, thin stubs. If your design splits analog and digital grounds, tie them together at the device VSS pin (pin 20) rather than near the connector.
Estimated: input clock flexibility. If the design uses the RS08 internal oscillator, no external crystal is required, simplifying the BOM. For designs requiring deterministic USB or UART timing, place a crystal on the RS08KB EXTAL/XTAL pins per the datasheet load-capacitance formula; typical values are 12 pF to 22 pF on each side. Route crystal traces short and shield them with a grounded guard ring to avoid radiated noise coupling into adjacent ADC channels during high-impedance sensor reads.
RS08KB code is NOT binary-compatible with HCS08 or S08 parts; if you migrate firmware between families you must recompile with the matching CodeWarrior or MCU Eclipse toolchain. The BDM interface on pin 8 must be accessible in production for in-system programming; do not assign it to GPIO-only functions or you will lose field firmware updatability. Finally, the NRND lifecycle flag means NXP may discontinue the part with short notice, so always qualify a second source such as the MC9S08PT16AVWJ before locking production.
Estimated: at 20 MHz and typical VDD = 3.3 V, the MC9RS08KB8CWJ574 consumes roughly 5-10 mA active, well below the SOIC-20 thermal limits; no heatsink is needed. However, the SOIC-20 wide-body package is rated to roughly 50 C/W theta_JA on a 1 oz copper 4-layer board, so for industrial -40C-to-105C operation verify the package power dissipation margin with the actual core duty cycle. Use copper pours under the exposed die pad area to spread heat if your application uses continuous-active mode for many seconds.
Compliance Information
Compliance information was not specified in the publicly summarized web snippets; consult the NXP RS08KB family datasheet and product page for RoHS, REACH, and lead-free declarations. AEC-Q100 is not applicable for this non-automotive-grade consumer/industrial MCU.
