IN Brief:
- MxL745950 supports currents to 50A, while the stackable MxL745951P is rated to 60A per device.
- MxL745951P adds PMBus/I²C telemetry, ±1% current monitoring, fault recording, and non-volatile configuration.
- Both devices are sampling now, with volume production expected in the fourth quarter of 2026.
MaxLinear has introduced two high-current electronic fuses for servers, accelerator trays, switches, fan trays, and other rack-scale computing equipment, combining integrated power-path protection with monitoring and fault-management functions.
The MxL745950 is a 16V device rated for currents up to 50A, while the MxL745951P supports up to 60A per device and can be operated in parallel for higher-current applications. Both integrate the principal power MOSFET rather than requiring the protection function to be constructed around a separate external switching device.
MxL745950 operates from 4V to 16V and specifies 1mΩ on-resistance. It provides analogue current sensing, temperature monitoring, and fault indication in a 5mm by 5mm LGA-32 package, positioning it as the simpler device where protection and local monitoring are required without a full digital management interface.
MxL745951P lowers the minimum input voltage to 2.9V, raises current capability to 60A, and specifies 0.79mΩ on-resistance in a 5mm by 4.5mm VQFN package. It adds PMBus and I²C interfaces, configurable protection thresholds and timers, non-volatile configuration storage, and black-box fault recording.
MaxLinear specifies ±1% current-monitoring accuracy on the 60A device. Its digital telemetry can report input and output voltage, current, power, and energy information, allowing the protected branch to become part of a wider rack-management system rather than remaining a binary fuse that is only noticed after it has disconnected a load.
Both devices provide protection against under-voltage, over-voltage, over-current, short-circuit, and over-temperature conditions, together with MOSFET fault diagnosis and reporting. Soft-start and inrush-control functions are intended to limit the current drawn when a card or subsystem is connected to an energised backplane or power distribution network.
Inrush becomes progressively harder to ignore as compute trays grow in power. Large input capacitances can draw substantial current when first connected, potentially disturbing neighbouring loads or activating protection elsewhere in the rack. An electronic fuse therefore sits between simple over-current protection and the wider hot-swap management required to insert, remove, and diagnose high-power modules.
The integrated MOSFET makes conduction resistance another significant design parameter. At tens of amperes, even milliohms translate into measurable voltage drop and heat. The specified 0.79mΩ path of the MxL745951P therefore affects both electrical efficiency and the thermal design around the package rather than serving merely as a comparative datasheet figure.
Parallel operation creates its own difficulty. Nominally identical power paths do not naturally share load evenly because MOSFET resistance, temperature, PCB copper, and connection impedance vary. MaxLinear has included active current balancing during start-up and steady-state operation to support applications requiring more current than a single 60A device can carry.
The digital functions address a different part of the rack problem. Protection hardware traditionally needs to disconnect a failed board quickly and perhaps assert a fault output. Dense AI systems increasingly require more detailed operating information, with controllers tracking power consumption, thermal behaviour, service events, and failures across trays, power shelves, switches, and cooling equipment.
Retained fault information can make intermittent problems easier to diagnose. A transient condition may have disappeared long before a technician reaches the rack, leaving little evidence beyond a reset subsystem. Recording electrical conditions around a trip can help distinguish between an input disturbance, load event, short circuit, thermal fault, or repeated protection problem.
PMBus connectivity also gives the power device a place inside the rack’s management architecture while leaving primary electrical protection local to the eFuse. That separation is important: software can provide configuration and visibility, but protection against a fast electrical fault cannot depend on a remote management controller responding in time.
MaxLinear is grouping the devices within its broader RackCommander control-plane portfolio, which also includes USB-UART connectivity, RS-485 devices, GPIO expansion, regulators, and management components. The engineering case for the eFuses is narrower and more concrete — high-current power-path protection combined with the telemetry required to understand what happened when that path fails.
MxL745950 and MxL745951P are sampling now and are being demonstrated during the OCP APAC Summit in Taipei. MaxLinear expects volume production in the fourth quarter of 2026, so the current availability is suitable for evaluation and qualification rather than being presented as unrestricted production supply.
The devices will not solve rack-scale power distribution by themselves. Conversion equipment, busbars, connectors, cooling, board regulators, and upstream protection remain part of the same electrical system. As individual compute trays consume more power, however, instrumenting and isolating each branch becomes increasingly difficult to leave to a conventional fuse and a fault LED.
