Posted On: Jul-2026 | Categories : Automotive
Automotive power distribution is moving from a passive network of wires, relays and replaceable fuses into a software-controlled system that determines where electricity flows, which loads remain active and how the vehicle responds to an electrical fault. This change is being driven by electric powertrains, advanced driver-assistance systems, central computers, steer-by-wire, brake-by-wire, connectivity and continuously powered security functions.
A modern vehicle can contain between 1,000 and 3,000 semiconductor chips, while increasingly complex models may carry software approaching 200 million lines of code. Supplying these electronic systems through a conventional architecture requires long cable runs, numerous electronic control units and large fuse-and-relay boxes. The wiring harness can consequently become one of the vehicle’s heaviest and most difficult components to install.
The industry’s response is not simply to install more efficient power converters. Automakers and semiconductor companies are redesigning the complete low-voltage electrical network. Zonal controllers are moving power management closer to vehicle loads, 48V buses are reducing current requirements, and smart electronic fuses are allowing software to isolate, monitor and recover circuits. Infineon, Texas Instruments, STMicroelectronics, Renesas and Monolithic Power Systems are positioning their power components around this wider architectural transition.
Traditional vehicles distribute electricity from a central battery and power box to individual control units through separate cable runs. Mechanical relays switch the loads, while melting fuses disconnect circuits when excessive current creates a safety risk. The arrangement is familiar and relatively inexpensive, but it was designed for vehicles containing far fewer electronic functions.
The weakness becomes more apparent as automakers add cameras, radar sensors, high-performance processors, electric pumps, active suspension, advanced lighting and automated-driving functions. Every additional system requires power, communication, circuit protection and fault diagnosis. A domain-based architecture can centralize computing for functions such as the powertrain or chassis, but the components belonging to one domain may still be distributed across the complete vehicle, preserving the requirement for long wiring runs.
Power Electronics News estimates that a domain-based vehicle may contain approximately 50 kilograms of wiring. The publication also reports that some zonal designs can reduce cabling weight substantially, although the exact saving depends on the vehicle platform, voltage architecture and number of zones. Less wiring can lower material requirements, simplify assembly and reduce vehicle weight, which is particularly important for battery-electric vehicles where mass directly affects driving range and battery sizing.
The commercial objective is therefore broader than replacing copper. Automakers want an electrical architecture that can be reused across several models, reconfigured through software and expanded when new features are added. This is turning the power-distribution network into a strategic part of the software-defined vehicle.
Zonal architectures organize electronic systems according to their physical location instead of assigning every device to a functional domain. A controller positioned in the front-left zone, for example, may manage nearby lights, sensors, suspension components, window motors and braking electronics even though these systems perform different functions.
Texas Instruments describes a two-level structure in which a power-distribution box supplies high-current electricity to zone control modules, while each zonal module distributes secondary power to nearby sensors, actuators and control units. Shortening the distance between the switch and its load reduces cable length and gives the local controller more detailed authority over power consumption.
The zonal controller is also becoming a meeting point between power and data. It can operate as a local communications gateway, collect diagnostic information and control semiconductor switches according to commands from the central computer. STMicroelectronics identifies the zonal control unit as a hub for smart power distribution as well as a gateway between vehicle domains.
This architecture supports platform reuse. An automaker can develop a common zone controller and then configure its outputs differently for a compact car, premium sport-utility vehicle or electric commercial vehicle. The physical hardware may remain similar while software determines which channels supply seats, lighting, pumps, sensors or comfort systems.
Infineon divides the evolution into three stages. The first relies predominantly on mechanical relays and fuses. The second places secondary power-distribution units closer to loads and partially replaces mechanical devices with semiconductors. The third integrates the secondary power-distribution function directly into the zonal controller, creating an almost entirely semiconductor-based local power network.
The third stage has the greatest potential to reduce wiring, but it also makes the zonal controller a safety-critical component. A hardware, software or communication failure cannot be allowed to remove power from steering, braking or perception systems. This requirement is increasing demand for redundant supplies, intelligent switches and independently configurable safe states.
A conventional fuse is designed to melt when current exceeds a defined level for a sufficient period. It protects the wire and load, but it cannot communicate its condition, change its trip curve or restore power after the underlying fault disappears. A technician must locate and replace it.
An automotive eFuse uses semiconductor switches, current sensing and control logic to provide more flexible circuit protection. Depending on the device, engineers can configure the nominal current, immediate shutdown threshold, delayed shutdown period, inrush response and recovery behaviour. The switch can report voltage, current, temperature and fault status to the vehicle controller.
The strongest recent evidence of this transition is Infineon’s July 2026 introduction of the SPOC Wire Guard BTS80009 SWPx 1ES. The 12V automotive eFuse supports currents of up to 34.5A and combines configurable wire protection, real-time diagnostics and a 24-bit serial peripheral interface. Its interface can be connected in a daisy chain, reducing the number of microcontroller connections required when several devices are installed. The first product is in production, while three additional on-resistance variants are planned before the end of 2026.
Infineon offers the product in four feature configurations. The basic version supports software-configurable wire protection and rapid external shutdown. Higher configurations add automatic low-power operation, configurable undervoltage protection and non-volatile memory for retaining an application-specific safe state. The family was developed for integration into systems requiring functional-safety support up to ASIL D.
Its single-channel design is commercially important. Multichannel devices can provide density and cost benefits, but a failure affecting one common package may threaten several loads. A single-channel architecture helps prevent a problem in one circuit from propagating into unrelated outputs, which is valuable for fail-operational ADAS and automated-driving systems.
STMicroelectronics is following the same direction with STi²Fuse, a family of intelligent switches intended to replace melting fuses. ST combines the devices with its Stellar automotive microcontrollers, allowing monitoring, control and protection functions to be managed within the wider vehicle architecture. The company positions this combination around lower wiring cost, reduced weight and compliance with ISO 26262 safety requirements.
Texas Instruments explains another advantage: recovery can be controlled by software. Instead of permanently opening the circuit, a smart eFuse can switch off the output and attempt a restart after a programmed interval. More advanced software can estimate wire temperature from current, resistance and thermal models before deciding whether restoring the circuit is safe.
This does not mean every circuit will use an integrated eFuse. TI notes that continuously operating loads above roughly 30A may require an external power transistor controlled by a high-side switch controller because heat dissipation can become difficult for an integrated device. Primary power-distribution boxes may need to handle hundreds of amperes before electricity is divided among downstream zones.
The likely outcome is a mixed architecture. High-current controllers and external MOSFETs will manage primary distribution, while integrated smart switches and eFuses protect secondary and zonal loads.
The traditional 12V low-voltage system is being stretched by central processors, ADAS hardware, electric actuators, active suspension, heating systems and by-wire controls. Supplying more power at 12V requires higher current, which increases resistive losses and forces manufacturers to use thicker conductors.
Raising the distribution voltage to 48V cuts the current required to deliver the same power to approximately one-quarter of the 12V requirement. Texas Instruments uses steer-by-wire as an example: a function operating at 48V may need around 25% of the load current required by a comparable 12V design. Lower current enables smaller cables and reduces thermal losses, weight and wiring cost.
Infineon is developing 48V switches, gate drivers, MOSFETs and power-distribution solutions for central computing, ADAS, brake-by-wire, steer-by-wire and infotainment loads. The company argues that moving battery-electric vehicle auxiliaries toward 48V can improve efficiency while reducing wiring complexity and assembly effort.
A 48V backbone could eventually eliminate some conventional power-distribution boxes. Zone controllers could receive the higher-voltage input and distribute both primary and secondary power locally. Because each output carries less current, the controller may support more channels without exceeding its thermal limits.
The shift will nevertheless be gradual. Many lights, sensors, microcontrollers and established actuators continue to operate at 12V. Early 48V vehicles therefore require DC/DC converters to supply legacy components. ST identifies 48V-to-12V conversion, power rail switching, PDUs and zonal controllers as interconnected elements of the new architecture rather than assuming that one voltage will immediately replace the other.
Operating at 48V also introduces more demanding electrical-safety conditions. Voltage arcing becomes a greater concern, requiring additional spacing between conductors and faster fault detection. TI expects voltage and current sensing to support rapid shutdown, while machine-learning algorithms could eventually help distinguish genuine arcs from ordinary vehicle transients and reduce false responses.
The practical architecture is therefore likely to be multi-voltage: a high-voltage battery for propulsion, a 48V network for power-intensive auxiliary functions and a 12V rail for lower-power or legacy loads.
A failed headlamp or comfort motor can usually be disconnected without making the vehicle uncontrollable. A failure affecting electronic braking, steering or an automated-driving processor requires a different response. The vehicle may need to retain enough power to complete a manoeuvre, warn the driver or reach a safe stopping position.
Smart power-distribution systems can combine separate battery or converter inputs, monitor both sources and redirect electricity when one rail fails. TI describes architectures in which vehicle software can route battery power from one zone to critical functions in another zone after a converter fault. Lower-priority loads can be disconnected when the remaining source cannot support every function simultaneously.
Supercapacitors may provide temporary support for short power interruptions or high-current transients. TI notes that supercapacitors are already used in functions such as electric door latches, helping preserve an exit path when the primary electrical supply is lost after a collision.
Infineon positions its PDU portfolio around the same fail-operational requirement. Its semiconductor-based switches provide online diagnostics, reset capability and fault isolation within approximately 100 to 500 microseconds. The company reports diagnostic coverage of up to 99% and supports designs requiring ISO 26262 compliance up to ASIL D.
Fast fault isolation has a commercial effect beyond safety compliance. A melting fuse must be sized to avoid nuisance trips during motor starts or capacitive inrush events. This can result in larger wires than normal operating current would otherwise require. Programmable electronic protection can follow a load-specific current-time profile more closely, allowing engineers to protect the actual cable without applying the same fixed margin to every circuit.
Renesas introduced the RAJ2810024H12HPD intelligent power device as an earlier step toward distributed semiconductor protection. The single-channel high-side switch uses a 6.10 by 6.50-millimetre package, reducing mounting area by approximately 40% compared with the company’s conventional TO-263 device. It also provides a typical on-resistance of 2.3 milliohms and current sensing intended to identify abnormal conditions even at low loads.
Detecting faults at low current is important because not every electrical problem begins as an immediate high-current short circuit. Connector degradation, partial wiring damage and changing load behaviour may appear first as smaller deviations. A semiconductor switch capable of reporting these changes can contribute to earlier diagnosis and potentially support predictive maintenance.
Renesas combines the IPD with a microcontroller-based power-distribution-box design in which fuse characteristics are programmed rather than fixed by a melting element. The company’s broader strategy is to sell compatible processing, analog and power devices as a system-level design rather than treating the intelligent switch as an isolated component.
This approach reflects a wider competitive change. Semiconductor suppliers are increasingly expected to provide reference architectures, safety documentation, software drivers, evaluation hardware and diagnostic tools. Automakers and Tier-1 suppliers are selecting development ecosystems as much as individual transistor specifications.
Vehicles continue consuming electricity after the ignition is switched off. Door access, alarm systems, telematics, remote applications, battery monitoring and software-update functions may remain active for extended periods. Battery-electric vehicles must support these loads without repeatedly activating an inefficient high-voltage conversion system.
Smart eFuses can place permanently powered loads into low-current states while retaining fault protection. When a door latch or security function becomes active, the switch can wake, supply full current and notify the local controller before returning to idle mode.
Infineon’s new SPOC Wire Guard includes an idle mode consuming only a few microamperes for permanently powered circuits. This is a small specification at the component level, but the cumulative impact becomes meaningful when dozens of protected outputs remain connected throughout a parked vehicle’s life.
The same principle is appearing in connected endpoint electronics. U-blox’s F11 GNSS platform dynamically activates its second frequency band only when additional positioning accuracy is required. The company reports consumption as low as 7 milliwatts in typical low-energy configurations, up to 40% less power during signal acquisition and up to 30% less during continuous tracking than its previous generation. Positioning accuracy in challenging environments can improve by as much as 30%.
The F11 is aimed primarily at telematics, fleet tracking, micromobility, wearables and industrial tracking rather than core vehicle power-distribution boxes. Its relevance lies in the design philosophy: electronic functions should draw maximum power only when conditions require it. As more connected modules remain active while vehicles are parked, adaptive endpoint consumption will complement the central power network’s ability to disconnect unnecessary loads.
Monolithic Power Systems identifies intelligent power management as a future development area in which vehicles make real-time distribution decisions according to driving conditions, available energy and passenger requirements. The concept shifts optimization from fixed hardware sizing toward continuous software control.
The first implementations are already visible in programmable trip curves, software-controlled restarts, load shedding and low-power modes. Future systems could go further by ranking loads dynamically. A vehicle experiencing a weak auxiliary battery might preserve braking, steering and external lighting while reducing cabin heating, entertainment power or non-essential sensor operation.
Software control also allows the same hardware to support different vehicle variants. Protection limits, startup sequences and safe states can be configured during production rather than redesigned through new fuse ratings and relay combinations. Over-the-air updates could refine energy-management strategies later, although safety-related changes would require careful validation and version control.
Greater flexibility brings cybersecurity and functional-safety obligations. A melting fuse cannot be reprogrammed by an attacker, while a connected power controller potentially can. The architecture must therefore separate authorized configuration from operating commands, protect stored safety parameters and preserve independent shutdown mechanisms when communications fail.
TI’s discussion of limp-home modes demonstrates this balance. A smart switch can be programmed before operation to maintain or disable specific outputs if communication with its microcontroller is lost. Software provides flexibility during normal operation, while a defined hardware-supported state protects critical functions when the software path is unavailable.
Infineon is combining smart switches with AURIX and TRAVEO microcontrollers, OPTIREG power supplies, XENSIV sensors and communication components. STMicroelectronics pairs STi²Fuse protection with Stellar controllers and devices for rail switching and voltage conversion. Texas Instruments offers eFuses, high-side controllers, ideal-diode controllers, current sensors and DC/DC converters. Renesas combines intelligent power devices with its microcontrollers and system-level reference designs.
The strategic opportunity is larger than the revenue from an individual fuse replacement. The company whose controller, communication interface and safety software are selected for a zonal platform may supply dozens of power channels across several vehicle models. Common software and safety documentation can also make it expensive for automakers to change suppliers after the architecture enters production.
Power distribution is therefore becoming part of the central contest for software-defined vehicle control. Semiconductor suppliers that previously sold protection devices as supporting components are now presenting complete fail-operational chipsets and development environments.
Mechanical fuses and relays will not disappear from every circuit immediately. They remain inexpensive, familiar and effective for loads that do not require diagnostics, reset capability or software configuration. Smart switches must justify their higher semiconductor cost through reduced wiring, smaller modules, easier assembly, better fault isolation or lower maintenance.
Thermal design also remains a constraint. Higher current through an integrated switch increases conduction losses, while placing many power outputs inside a zonal controller concentrates heat. Engineers must balance channel density with package resistance, cooling, board area and peak-load behaviour.
The transition to 48V introduces arcing, isolation and conversion challenges, while mixed-voltage networks can increase short-term complexity. Zonal architectures reduce long cable runs but place more responsibility on local controllers. Software-controlled protection improves flexibility but expands the amount of code, testing and cybersecurity work required before production.
These limitations explain why several generations of power distribution will coexist. Some vehicles will use a centralized fuse box with selected semiconductor switches. Others will employ distributed PDUs, while the most advanced platforms will integrate secondary distribution directly into zonal controllers.
The defining Automotive Power Distribution Trend is not one new fuse, voltage rail or controller. It is the integration of all three into a network that can observe, prioritize, isolate and restore electrical loads.
Infineon’s 34.5A SPOC Wire Guard shows that software-configurable eFuses are moving into production-capable current ranges. Texas Instruments demonstrates how zonal controllers can reduce cabling and use software to recover circuits. STMicroelectronics is combining intelligent switches with real-time automotive controllers, while Renesas has reduced power-switch size and improved low-load current detection. U-blox shows how connected endpoints can make their own power consumption responsive to operating conditions.
As ADAS, central computing and by-wire systems expand, continuous electrical availability will become as important as computing performance. The successful suppliers will be those that allow automakers to deliver more electronic capability without proportionally increasing wire weight, standby losses, fuse-box size and failure risk.
The vehicle power network is consequently moving from passive infrastructure to active control. In the software-defined vehicle, electricity will not simply flow wherever a wire has been installed. It will be measured, routed and protected according to software-defined priorities throughout the vehicle’s operating life