NXP Semiconductors MC9RS08KB12CFK

Overview

MC9RS08KB12CFK from NXP Semiconductors (formerly Freescale) is an 8-bit RS08 core microcontroller in a 24-pin QFN package, featuring 12 KB flash, 254-byte RAM, 10-bit ADC with 12 channels, and integrated peripherals including TPM, IIC, SCI, ACMP, and RTI. It operates from 1.8 V to 5.5 V at up to 20 MHz CPU frequency across –40 °C to 85 °C, targeting low-power embedded control in industrial sensors and appliance subsystems.

For engineers reviewing the MC9RS08KB12CFK datasheet, MC9RS08KB12CFK pinout, MC9RS08KB12CFK application, or MC9RS08KB12CFK equivalent, key selection criteria include its 24-pin QFN thermal resistance (θJA = 113 °C/W), single-wire background debug interface, 0.2% internal clock trimming accuracy, stop-mode current of 1.15 μA (typical at 5 V), and support for LIN-compliant SCI operation.

Technical Context

The MC9RS08KB12CFK implements an RS08 CPU core - a subset of the HC08 instruction set augmented with BGND - using a single global interrupt vector and no nested interrupts. Its memory subsystem includes 12 KB of on-chip flash with block protection and 254-byte RAM, both accessible across full voltage (1.8–5.5 V) and temperature (–40 to 85 °C) ranges.

System timing relies on dual clock sources: an external crystal/ceramic oscillator (31.25 kHz–16 MHz) and an internal clock source (ICS) with FLL-based frequency multiplication and factory-trimmed reference enabling ±2% deviation over voltage/temperature. Power management supports Wait and Stop modes with wakeup via RTI, KBI, ADC, ACMP, SCI, or LVD.

Key Specifications

Pinout & Package

MC9RS08KB12CFK is housed in a 24-pin QFN package (Case 1982-01) with 4×4 mm body, 0.5 mm pitch, and exposed thermal pad. The package uses copper wire bonding (per Freescale QFN Addendum Rev. 0, 98ASA00602D) and supports reflow soldering per JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC9RS08KA2CFK, the MC9RS08KB12CFK provides 6× more flash and 2× more RAM in the same 24-pin QFN footprint; versus MC9S08AC128CFK, it offers lower power consumption and smaller code size but lacks advanced peripherals like CAN and enhanced PWM.

Availability

MC9RS08KB12CFK is available at Aetrix Electronics and suitable for industrial sensor nodes, smart appliance subsystems, and automotive body control modules requiring stable component supply, long-term lifecycle support, and consistent QFN packaging.

Supply support for MC9RS08KB12CFK 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, now specializing in secure connectivity solutions for automotive, industrial, and IoT markets.

The MC9RS08KB12CFK belongs to NXP's RS08 family - a cost-optimized, ultra-low-power 8-bit MCU line designed for simple embedded control tasks where minimal code size, fast startup, and sub-μA stop-mode current are critical.

FAQ

What is the maximum operating frequency of the MC9RS08KB12CFK CPU core?

The MC9RS08KB12CFK CPU core operates at up to 20 MHz across the full supply voltage range of 1.8 V to 5.5 V and temperature range of –40 °C to 85 °C. This frequency is achieved using either the internal clock source (ICS) with FLL or an external crystal/resonator connected to the XOSC pins. Bus frequency is limited to 10 MHz, and actual core speed depends on bus configuration and clock source selection.

Does the MC9RS08KB12CFK support debugging during operation?

Yes, the MC9RS08KB12CFK supports in-circuit debugging via its single-wire background debug interface (BKGD pin). It allows breakpoint setting, register inspection, and flash programming without halting system clocks. The interface requires only one dedicated pin and does not need additional debug hardware beyond a compatible programmer, making it ideal for space-constrained designs where JTAG is impractical.

Can the MC9RS08KB12CFK operate from a 1.8 V supply in all modes?

Yes, the MC9RS08KB12CFK is fully specified to operate from 1.8 V in Run, Wait, and Stop modes across –40 °C to 85 °C. At 1.8 V, it delivers 2.40 mA typical run current (fBus = 10 MHz), 630.64 μA typical wait current (fBus = 2 MHz), and 0.39 μA typical stop current. RAM retention is guaranteed down to 0.81 V, enabling graceful shutdown during brownout conditions.

What analog peripherals are integrated into the MC9RS08KB12CFK?

The MC9RS08KB12CFK integrates a 12-channel, 10-bit successive-approximation ADC with 2.5 μs conversion time, automatic compare function, and internal bandgap reference; plus a rail-to-rail analog comparator (ACMP) with selectable internal bandgap reference and Stop-mode operation. Both peripherals support hardware triggering and share dedicated analog input pins (ADP0–ADP11), enabling simultaneous sensing and threshold detection without CPU intervention.

Is the MC9RS08KB12CFK pin-compatible with other members of the RS08 family?

No - the MC9RS08KB12CFK in its 24-pin QFN package is not pin-compatible with other RS08 variants such as the 8-pin SOIC/DFN MC9RS08KB2 or 16-pin TSSOP MC9RS08KB4. Pin assignments differ significantly across packages due to varying I/O counts and peripheral mappings. Migration requires PCB redesign; however, software compatibility is maintained within the RS08 instruction set architecture.