20 MHz RS08 core in a 16-TSSOP — what this MCU brings to the BOM
The NXP MC9RS08KB4CTG is an 8-bit microcontroller built around the RS08 core, clocked at 20 MHz. It carries 4 KB of on-chip Flash and 126 bytes of RAM — enough for a single control loop, a sensor readout, or a simple PWM sequence. The 14 general-purpose I/O lines and the 8-channel 10-bit ADC cover basic analog sensing without an external converter. Supply range spans 1.8 V to 5.5 V. The internal oscillator keeps the BOM count low — no external crystal or resonator needed unless the application demands tighter timing. On-chip peripherals include a low-voltage detect (LVD), power-on reset (POR), a PWM timer, and a watchdog timer (WDT). I²C and SPI are available for connecting to a temperature sensor, an EEPROM, or a small display. The part is rated for -40°C to 85°C, which covers outdoor telecom cabinets, factory-floor sensor nodes, and under-hood automotive modules that don't require AEC-Q100 certification.
4 KB Flash, 126 B RAM — sizing the memory budget
The 4 KB program memory is a hard limit for firmware size. This part suits a state machine, a fan-speed controller, or a simple keypad scanner — not a protocol stack or a data logger. The 126 bytes of RAM handle a few variables and a small stack; anything larger needs external SRAM or a bigger MCU.
Active lifecycle — no LTB clock ticking
The MC9RS08KB4CTG carries an Active product status. For a BOM line that needs a stable, long-term supply, this MCU doesn't carry the obsolescence risk of an NRND or EOL part.