NXP Semiconductors MC9RS08KB4CFK

Overview

MC9RS08KB4CFK from NXP Semiconductors (formerly Freescale) is an 8-bit RS08 core microcontroller with 4 KB flash, 126-byte RAM, and integrated peripherals including 10-bit ADC, analog comparator, TPM timer/PWM, IIC, SCI, and keyboard interrupt module. It operates from 1.8 V to 5.5 V at up to 20 MHz CPU frequency and supports industrial temperature range (–40 °C to 85 °C). Used in cost-sensitive embedded control applications such as appliance panels and sensor interfaces.

For engineers reviewing the MC9RS08KB4CFK datasheet, MC9RS08KB4CFK pinout, MC9RS08KB4CFK application, or MC9RS08KB4CFK equivalent, key selection considerations include its 24-pin QFN package (case 1982-01), single-wire background debug interface, low-power stop mode (0.39 µA typical at 1.8 V), internal clock source with ±2% deviation over voltage/temperature, and 12-channel ADC with 2.5 µs conversion time.

Technical Context

The MC9RS08KB4CFK implements a subset of the HC08 instruction set with added BGND instruction and a single global interrupt vector. Its RS08 CPU features a 2-stage pipeline and executes instructions in one or two bus cycles, enabling deterministic timing for real-time control loops.

System-level timing is managed via multiple clock sources: external crystal/ceramic resonator (31.25 kHz–16 MHz) or internal clock source (ICS) with frequency-locked-loop (FLL) and precision-trimmed reference (0.2% resolution, ±2% deviation). Power management includes Wait and Stop modes with wakeup capability from RTI, KBI, ADC, ACMP, SCI, and LVD.

Key Specifications

Pinout & Package

MC9RS08KB4CFK is packaged in a 24-pin QFN (quad flat no-lead) with exposed thermal pad, case number 1982-01, footprint per JEDEC MO-220. The package uses copper wire bonding per Freescale QFN migration addendum Rev. 0 (2014).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with MC9RS08KB8CFK, the MC9RS08KB4CFK offers identical functionality at reduced memory capacity - ideal for cost-optimized designs with fixed firmware footprints. Versus S9KEAZ128AMLH, it delivers lower system cost and power but lacks ARM ecosystem tooling and advanced peripherals.

Availability

MC9RS08KB4CFK is available at Aetrix Electronics and suitable for home appliance control panels, industrial sensor nodes, and smart lighting dimmer modules requiring stable component supply and long-term industrial lifecycle support.

Supply support for MC9RS08KB4CFK includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor company formed from the spin-off of Philips' semiconductor division and later the acquisition of Freescale Semiconductor in 2015.

The MC9RS08KB4CFK belongs to the RS08 family - a cost-optimized 8-bit MCU line designed for simple embedded control tasks in appliances, consumer electronics, and industrial subsystems where low gate count, minimal power, and small footprint are critical.

FAQ

What is the maximum operating frequency of the MC9RS08KB4CFK CPU core?

The MC9RS08KB4CFK CPU core operates at up to 20 MHz across the full industrial temperature range (–40 °C to 85 °C) and supply voltage range (1.8 V to 5.5 V). This frequency is achievable using either the internal clock source (ICS) with FLL or an external crystal/resonator. Bus frequency is limited to 10 MHz when using the ICS module, while external oscillators support full 20 MHz operation.

Does the MC9RS08KB4CFK support in-circuit debugging, and what interface is used?

Yes, the MC9RS08KB4CFK supports in-circuit debugging via a single-wire background debug (BKGD) interface. This interface uses the PTA4 pin and requires only one physical connection plus ground. It enables full read/write memory access, register inspection, and single-breakpoint capability during development - all without halting real-time peripheral operation.

What are the low-power modes supported by the MC9RS08KB4CFK, and how do they differ?

The MC9RS08KB4CFK supports Wait and Stop modes. In Wait mode, the CPU halts but system clocks remain active, allowing peripherals like ADC or TPM to operate and generate interrupts. In Stop mode, all clocks stop and the voltage regulator enters standby, reducing current to 0.39 µA typical at 1.8 V. Both modes support wakeup via RTI, KBI, ADC, ACMP, SCI, or LVD events - making them suitable for battery-powered sensing applications.

Can the MC9RS08KB4CFK's ADC operate while the device is in Stop mode?

Yes, the MC9RS08KB4CFK's 10-bit ADC can perform conversions while the device is in Stop mode. This feature allows ultra-low-power data acquisition - for example, triggering a conversion upon wakeup from Stop mode using an external event, then completing the sample before returning to low-power state. The ADC adder current in Stop mode is specified at 54.77 µA typical (1.8 V, –40 °C).

What package type and pin count does the MC9RS08KB4CFK use, and is it RoHS compliant?

The MC9RS08KB4CFK uses a 24-pin QFN package (case number 1982-01) with exposed thermal pad and copper wire bonding. It complies with RoHS Directive 2011/65/EU and is lead-free. The package footprint follows JEDEC MO-220 standards and is compatible with standard reflow soldering processes used in high-volume manufacturing.