NXP Semiconductors MC33FS8420G0KS

Overview

MC33FS8420G0KS from NXP Semiconductors is an ASIL B–capable automotive fail-safe system basis chip (SBC) integrating a VPRE synchronous buck controller, two low-voltage synchronous buck converters (BUCK1 and BUCK2), one boost converter, and two LDOs. It delivers up to 3.6 A peak per buck rail, supports 60 V DC input, and features SPI/I²C control with CRC, fail-safe output (FS0B), and power-good/reset signaling - designed for radar and ADAS domain controller power management.

For engineers reviewing the MC33FS8420G0KS datasheet, MC33FS8420G0KS pinout, MC33FS8420G0KS application, or MC33FS8420G0KS equivalent, this device enables deterministic power sequencing, EMC-optimized frequency synchronization (FIN/FOUT), thermal and overvoltage supervision across six monitoring inputs (VMON1–VMON4, VCOREMON, VDDIOMON), and functional safety compliance per ISO 26262 up to ASIL B.

Technical Context

The MC33FS8420G0KS implements a multi-rail power architecture with independent control loops for VPRE (external MOSFET controller), BUCK1 (MCU core supply with SVS), and BUCK2 (multi-phase capable up to 7.2 A peak when paired with BUCK1). Its fail-safe state machine integrates ABIST/LBIST, challenger watchdog, and dedicated FCCU monitoring inputs (FCCU1/FCCU2) for MCU-level fault detection.

It supports configurable power-up sequencing across eight slots, deep fail-safe autoretry (infinite), and real-time analog monitoring via AMUX output. Safety-critical functions-including PGOOD, RSTB, FS0B, and interrupt (INTB)-are hardware-decoupled from the main power management logic to meet ASIL B partitioning requirements.

Key Specifications

Pinout & Package

MC33FS8420G0KS is housed in a HVQFN56 package (8 mm × 8 mm × 0.85 mm, 0.5 mm pitch, wettable flank, dimple variant for KS suffix) with exposed thermal pad (EP) connected to GNDFS/GND.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar automotive SBC applications.

Compared with MC33FS8420G0KS, MC33FS8425G0KS adds FCCU monitoring and extra VMON channels for tighter MCU coupling, while MC33FS8520A0KS upgrades to ASIL D with dual watchdog and ERRMON - both require revalidation of safety mechanisms and OTP configuration.

Availability

MC33FS8420G0KS is available at Aetrix Electronics and suitable for radar sensor modules, ADAS domain controllers, and automotive camera systems requiring stable component supply, long-term automotive qualification, and ISO 26262-compliant power management.

Supply support for MC33FS8420G0KS 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 specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with leadership in automotive microcontrollers and power management.

The FS84 product line delivers ASIL B–certified system basis chips optimized for radar, vision, and domain controller power architectures - emphasizing functional safety, EMC robustness, and flexible OTP configuration for automotive Tier 1s.

FAQ

What is the maximum output current supported by BUCK1 in the MC33FS8420G0KS?

The MC33FS8420G0KS supports up to 4.5 A peak output current on its BUCK1 regulator, configured at 1.8 V for MCU core supply. This rating assumes proper thermal design with the exposed pad (EP) soldered to a thermal plane, and operation within AEC-Q100 Grade 1 temperature limits (−40 °C to +125 °C). Current limit is fixed by OTP programming and cannot be adjusted in-circuit.

Does the MC33FS8420G0KS support multiphase operation between BUCK1 and BUCK2?

Yes, the MC33FS8420G0KS supports multiphase operation between BUCK1 and BUCK2, enabling combined peak current delivery up to 7.2 A on a single output rail. Phase shifting is controlled via OTP configuration (delay values programmed at factory), and both regulators share the same 2.22 MHz switching frequency. No external phase-control circuitry is required.

How does the fail-safe output (FS0B) behave during thermal shutdown?

During thermal shutdown (TSD), the MC33FS8420G0KS asserts its FS0B pin as an active-low open-drain signal and enters deep fail-safe mode with infinite autoretry. The output remains asserted until either the die temperature falls below the TSD release threshold or a valid reset sequence (e.g., VSUP cycle or SPI-initiated recovery) is executed - ensuring no unsafe power restoration.

Can the MC33FS8420G0KS be used with both SPI and I²C interfaces simultaneously?

No, the MC33FS8420G0KS supports SPI or I²C communication exclusively - not concurrently. Interface selection is determined at power-up by the state of the DBG pin and fixed by OTP configuration. Once selected, the unused interface pins (e.g., SCL/SDA when using SPI) are disabled and must not be driven externally to avoid contention.

What is the purpose of the AMUX pin on the MC33FS8420G0KS?

The AMUX pin on the MC33FS8420G0KS provides time-multiplexed analog output of internal measurements - including BUCK1/BUCK2/BOOST output voltages, die temperature, and VMON inputs - selectable via SPI or I²C commands. It enables MCU ADC-based health monitoring without additional external sensors, reducing BOM cost and board space.

Is the MC33FS8420G0KS pin-compatible with other FS84 family members like MC33FS8430G0KS?

Yes, all FS84 devices including MC33FS8420G0KS and MC33FS8430G0KS are pin-to-pin and software compatible per the datasheet. However, functional differences exist: MC33FS8430G0KS adds BUCK3, while MC33FS8420G0KS omits it. PCB layout is identical, but firmware must disable unused regulators and adjust sequencing slots accordingly.