NXP Semiconductors MC9RS08KB4CWJ

Overview

MC9RS08KB4CWJ from NXP Semiconductors (formerly Freescale) is an 8-bit RS08 core microcontroller in a 24-pin QFN package, featuring 4 KB flash, 126-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 across –40 °C to 85 °C and supports low-power stop/wait modes - used in battery-powered sensor nodes and industrial control interfaces.

For engineers reviewing the MC9RS08KB4CWJ datasheet, MC9RS08KB4CWJ pinout, MC9RS08KB4CWJ application, or MC9RS08KB4CWJ equivalent, this page delivers verified electrical specs, validated QFN-24 pin mapping, real-world use cases for embedded sensing and serial interface control, and two confirmed alternative parts with documented functional and packaging differences.

Technical Context

The MC9RS08KB4CWJ implements a subset of the HC08 instruction set with BGND support and a single global interrupt vector. Its internal clock source (ICS) uses a frequency-locked loop (FLL) with precision-trimmed internal reference enabling ±0.2% resolution and ≤2% deviation over voltage/temperature - supporting bus frequencies up to 10 MHz.

System protection includes COP reset with dedicated 1 kHz low-power oscillator, low-voltage detection (LVD) with reset/interrupt, illegal opcode/address detection, and flash-block protection. Wakeup from stop mode is supported via RTI, KBI, ADC, ACMP, SCI, and LVD events.

Key Specifications

Pinout & Package

MC9RS08KB4CWJ 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 copper-wire bonding migration (per QFN_Addendum Rev. 0) ensures improved reliability versus legacy gold-wire versions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC9RS08KB4CWJ, MC9RS08KB8CWJ offers double flash/RAM in identical packaging for seamless firmware scaling, while S9KEAZ128AMLH provides ARM-based performance and peripheral richness at the cost of board redesign and toolchain migration.

Availability

MC9RS08KB4CWJ is available at Aetrix Electronics and suitable for industrial sensor interfaces, smart metering subsystems, and home appliance control panels requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MC9RS08KB4CWJ 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 leader delivering secure, scalable solutions for automotive, industrial, IoT, and communication infrastructure markets.

The MC9RS08KB4CWJ belongs to the RS08 family - designed specifically for cost-sensitive, ultra-low-power embedded control applications where small code footprint, minimal external components, and robust operation across wide voltage/temperature ranges are essential.

FAQ

What is the maximum bus frequency supported by the MC9RS08KB4CWJ?

The MC9RS08KB4CWJ supports a maximum bus frequency of 10 MHz, achieved via its internal clock source (ICS) with frequency-locked loop (FLL). This is enabled by precision trimming of the internal reference, delivering ≤2% deviation over the full operating voltage (1.8–5.5 V) and temperature (–40 °C to 85 °C) range. External crystal oscillators can run up to 16 MHz but require configuration through the XOSC module.

Does the MC9RS08KB4CWJ support debugging without external hardware tools?

Yes, the MC9RS08KB4CWJ includes a single-wire background debug interface (BDC) accessible via the BKGD pin (PTA4). This allows full in-circuit debugging - including breakpoint setting, register inspection, and flash programming - using only a UART-to-BKGD adapter. No JTAG emulator or additional debug headers are required, simplifying development and reducing test fixture complexity.

Can the MC9RS08KB4CWJ operate in stop mode while retaining ADC functionality?

Yes, the MC9RS08KB4CWJ's 10-bit ADC supports operation in stop mode. It can perform conversions triggered by hardware events (e.g., RTI timeout or KBI edge) and complete measurements with 2.5 μs conversion time while consuming as little as 0.39 μA at 1.8 V. This enables precise, low-power sensor sampling without waking the CPU - critical for battery-operated devices.

What are the absolute maximum ratings for VDD and digital input voltage on the MC9RS08KB4CWJ?

The MC9RS08KB4CWJ has an absolute maximum VDD rating of –0.3 V to 5.8 V, and digital input voltage (VIn) must stay within –0.3 V to VDD + 0.3 V. Exceeding these limits risks permanent damage. Input pins are internally clamped to VSS and VDD (except RESET/VPP, clamped to VSS only), and DC injection current per pin is limited to ±0.2 mA - requiring external current-limiting resistors if interfacing with voltages beyond VDD or below VSS.

How does the MC9RS08KB4CWJ handle low-voltage conditions during operation?

The MC9RS08KB4CWJ integrates a programmable low-voltage detect (LVD) circuit with thresholds ranging from 1.80 V to 2.05 V (falling/rising). It can generate either a reset or interrupt signal upon detection, allowing firmware to safely save state or initiate shutdown. Combined with RAM retention down to 0.81 V, this ensures data integrity and graceful recovery during brown-out events - eliminating need for external supervisor ICs in most designs.