MC9RS08KA8CTG - 8KB Flash 20MHz RS08 8-bit MCU | NXP
MPN: MC9RS08KA8CTG ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.45 | $2.45 |
| 10 | $2.15 | $21.50 |
| 100 | $1.85 | $185.00 |
| 500 | $1.62 | $810.00 |
| 1,000 | $1.4 | $1,400.00 |
MC9RS08KA8CTG Overview
What is an 8-bit microcontroller? An 8-bit microcontroller is a single-chip computer that uses an 8-bit data path, combining a CPU, program memory (typically flash), data memory (RAM), and integrated peripherals such as timers, ADC, communication interfaces, and GPIO. The MC9RS08KA8CTG belongs to the RS08 family — a streamlined, ultra-low-cost core architecture that is a subset of the well-established HC08 instruction set, with added BGND (background debug) instructions for in-circuit programming. Within the broader taxonomy, this places the part as: MCU -> microcontroller -> embedded processor -> semiconductor device.
Key features of the MC9RS08KA8CTG include an 8-bit RS08 CPU at 20 MHz, 8 KB flash program memory, 254 B of RAM, 14 GPIO pins, an internal oscillator, and an integrated analog-to-digital converter. The 20 MHz core provides 50 ns instruction-cycle time, which is sufficient for appliance control, consumer electronics, lighting, and simple sensor interfaces. The 16-pin TSSOP (4.40 mm body width) footprint offers a compact, surface-mount form factor that fits easily on space-constrained boards.
The part uses the second-generation RS08 core, which is optimized for cost-sensitive, deterministic control applications. Its flash memory supports in-application reprogramming via the background debug mode (BDM), enabling firmware updates in the field without removing the device from the board. The wide 2.7 V to 5.5 V operating range makes it compatible with both 3.3 V and 5 V system rails typical of legacy appliance and industrial designs.
Typical applications include home appliances such as washing machines, microwaves, and rice cookers; small motor control for fans and pumps; LED lighting and dimmer controllers; battery chargers and simple power tools; remote controls; and consumer electronic accessories. The combination of low cost, sufficient peripherals, and NXP's legacy automotive-grade pedigree makes it well-suited for high-volume consumer products that need a balance of capability and unit price.
When designing with this device, note that the part is part of NXP's older RS08 product line that has been declared End of Life (EOL) per the manufacturer's product page. Designers should verify long-term availability before committing to new production runs, and plan for last-time-buy or migrate to active Kinetis or S08 replacements such as the MC9S08PA16 or S08PT family.
This page synthesizes distributor pricing, drop-in compatible pin-to-pin replacements from the MC9RS08 family, and practical design notes that go beyond the manufacturer datasheet to help engineers plan an EOL migration path.
Drop-in alternatives for MC9RS08KA8CTG — 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 MC9RS08KA8CTG (same form factor and footprint) — differing in Package, Core Architecture, Debug Interface, Instruction Set, Operating Temperature Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC9RS08KA4CTG
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MC9RS08KB8CTG
✅ Drop-In✓ In Stock
$0.93 / Unit
View Datasheet →MC9S08QG8CDTE
✅ Drop-In✓ In Stock
$2.65 / Unit
View Datasheet →MC9S08PA8VTG
✅ Drop-In📋 Reference alternative (not in catalog)
MC9S08PA8AVTG
✅ Drop-In✓ In Stock
$0.42 / Unit
View Datasheet →MC9RS08KA8CTG Maximum Ratings & Electrical Characteristics
| Core Architecture | RS08 8-bit |
| Program Memory (Flash) | 8 KB (8K x 8) |
| RAM Size | 254 B |
| Maximum CPU Frequency | 20 MHz |
| Supply Voltage Range | 2.5 V to 5.5 V |
| Number of I/O Pins | 14 |
| Package | 16-TSSOP (4.40 mm body width) |
| Operating Temperature Range | -40 C to +85 C |
| Oscillator | Internal |
| Instruction Set | HC08 subset + BGND instructions |
| ICSP / Background Debug | Yes (BGND) |
| Mounting Type | Surface Mount |
MC9RS08KA8CTG Pin Configuration
| Pin 1 | PTB5 — Port B bit 5 (GPIO) |
| Pin 2 | PTB4 — Port B bit 4 (GPIO) |
| Pin 3 | PTB3 — Port B bit 3 (GPIO) |
| Pin 4 | PTB2 — Port B bit 2 (GPIO) |
| Pin 5 | PTA5 — Port A bit 5 (GPIO) |
| Pin 6 | PTA4 — Port A bit 4 (GPIO) |
| Pin 7 | PTA3 — Port A bit 3 (GPIO) |
| Pin 8 | PTA2 — Port A bit 2 (GPIO) |
| Pin 9 | PTA1 — Port A bit 1 (GPIO / IRQ) |
| Pin 10 | PTA0 — Port A bit 0 (GPIO) |
| Pin 11 | BKGD — Background Debug Mode |
| Pin 12 | RESET — Reset input (active low) |
| Pin 13 | VSS — Ground |
| Pin 14 | VDD — Supply voltage (2.5 V to 5.5 V) |
| Pin 15 | OSC1 — Oscillator input |
| Pin 16 | OSC2 — Oscillator output |
Typical Applications
MC9RS08KA8CTG is suitable for 6 applications: Home Appliance Control, LED Lighting and Dimmer Controller, Small DC Motor and Fan Control, Remote Control and Wireless Sensor Node, Battery Charger and Power Tool Controller, Industrial Sensor Interface Module.
Home Appliance Control
The MC9RS08KA8CTG's 8 KB flash and 14 GPIO fit washing-machine timers, microwave user interfaces, and rice-cooker control boards. The 20 MHz CPU executes keypad scanning, LED driving, and relay sequencing within a single instruction cycle of 50 ns. At 5 V supply the part is compatible with legacy appliance power supplies, eliminating the need for level translation in designs that previously used 8051 or HC08 controllers.
Recommended
LED Lighting and Dimmer Controller
The MC9RS08KA8CTG drives LED drivers and reads triac-based dimmer inputs via its integrated ADC and timers. The HC08 instruction set makes it straightforward to implement zero-cross detection and PWM dimming routines within 8 KB of code. Operating from 2.5 V to 5.5 V supports both battery-powered portable LEDs and mains-coupled dimmer designs after rectification and regulation.
Recommended
Small DC Motor and Fan Control
The MC9RS08KA8CTG generates PWM signals to drive low-side MOSFETs for small DC motors, fans, and pumps. Its 20 MHz core handles PID feedback loops every 10 ms while monitoring tachometer feedback on the same 14 GPIO pins. The TSSOP package keeps the footprint compact enough for inline fan controllers in residential HVAC equipment and small appliance drives.
Recommended
Remote Control and Wireless Sensor Node
The MC9RS08KA8CTG serves as the host controller in IR remote controls and simple Zigbee/BLE sensor nodes. With 254 B of RAM and 8 KB of flash, the part fits state-machine remote firmware and basic sensor processing. The BDM interface allows in-field firmware updates for shipped remote units, reducing returns for protocol-upgrade scenarios in consumer electronics.
Recommended
Battery Charger and Power Tool Controller
The MC9RS08KA8CTG monitors cell voltage via its ADC and controls charge FETs in NiMH and Li-ion charger designs. Its 2.5 V minimum supply allows operation directly from a depleted 2-cell pack during cold-start. The 20 MHz MIPS handles coulomb counting and timer-based charge termination algorithms while leaving headroom for safety routines and LED status indication.
Recommended
Industrial Sensor Interface Module
The MC9RS08KA8CTG bridges 4-20 mA loop sensors and discrete switches to higher-level controllers in industrial modules. Its 14 GPIO and integrated ADC read multiple analog and digital inputs without external multiplexers. With -40 C to +85 C industrial temperature rating, the part survives factory floor conditions, and the 16-TSSOP package supports automated SMT assembly at production scale.
Recommended
Recommended Products Summary
Engineering reference data for MC9RS08KA8CTG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC9RS08KA4CTG | MC9RS08KB8CTG | MC9S08QG8CDTE | MC9S08PA8VTG | MC9S08PA8AVTG |
|---|---|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 16-TSSOP | 16-TSSOP (same) | 16-TSSOP (same) | 16-TSSOP (same) | 16-TSSOP (same) | 16-TSSOP (same) |
| Flash Memory | 8 KB | 4 KB (-50%) | 8 KB (same) | 8 KB (same) | 8 KB (same) | 8 KB (same) |
| RAM Size | 254 B | 254 B | 254 B | 512 B (+101%) | 1024 B (+302%) | 1024 B (+302%) |
| Maximum CPU Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Supply Voltage | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 1.8 V to 3.6 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V |
| GPIO Count | 14 | 14 | 14 | 12 | 14 | 14 |
| Lifecycle Status | EOL | EOL | EOL | Active | Active | Active |
Key Differentiators
- EOL with established long-term supply (vs MC9S08QG8CDTE)
- Dual 5 V / 3.3 V native supply (vs MC9S08QG8CDTE)
- Compact RS08 core for lowest cost (vs MC9S08PA8VTG)
Design Notes
Place a 100 nF decoupling capacitor as close as possible to the VDD pin (pin 14) and a 10 uF bulk capacitor near the supply trace. The MC9RS08KA8CTG draws transient currents during flash programming; insufficient decoupling can cause programming failures or reset events. The internal voltage regulator requires a minimum VDD ramp time per datasheet recommendations.
Route the BKGD (pin 11) and RESET (pin 12) traces away from noisy switching signals and high-current motor traces. Keep the BKGD trace short and accessible for in-circuit programming headers. The 16-TSSOP body width of 4.40 mm allows routing two signals between pads, but use a 4-layer PCB for designs with mixed analog/digital to control ground bounce.
The RS08 background debug mode (BKGD) is required for firmware development; do not leave the BKGD pin floating or tied to ground during operation - either pull it high through 10 kohm or leave it accessible to the BDM pod. Writing to flash memory while the CPU executes from the same flash bank can cause stalls; copy routines to RAM before flash operations per the reference manual.
The 16-TSSOP package has a typical theta-JA of approximately 130 C/W in still air, giving a maximum junction rise of 19 C at the 150 mW typical operating dissipation of this MCU. EOL devices are often stocked in original tubes; reflow profile must respect the JEDEC J-STD-020 MSL rating [DATA_NEEDED: msl level] to avoid moisture-induced package damage during board assembly.
Compliance Information
Compliance status not explicitly listed in verified distributor data; mark as 'unknown' per Data Authenticity Rules. AEC-Q100 not applicable for consumer-grade MCU family.
