RS31391 - Stackable 60A eFuse with PMBus Digital Telemetry

RS31391 Intelligent PMBus eFuse for AI Point-of-Load Protection

Intelligent Protection for High-Current Point-of-Load Power Rails

The RS31391 is a 4V to 16V, 60A stackable eFuse with integrated PMBus® digital configuration, telemetry, and diagnostics, optimized to protect intermediate bus and point-of-load (POL) power rails in AI servers, accelerators, networking equipment, storage systems, and high-performance computing platforms. Featuring an integrated 0.8mΩ MOSFET, 60A continuous and 80A peak current capability, configurable protection thresholds, precision current monitoring, and comprehensive fault protection, the RS31390 delivers intelligent power protection for modern computing systems.

Designed for placement between the intermediate bus converter (IBC) and the multiphase voltage regulator, the RS31390 safeguards high-current power rails while providing real-time telemetry, remote configuration, and system diagnostics. Its stackable architecture enables multiple devices to operate in parallel, providing scalable current capability while maintaining PMBus configuration and telemetry.

Optimized for Intermediate Bus and Point-of-Load Protection

Following the intermediate bus converter, today’s AI power architectures require intelligent protection for the high-current rails feeding multiphase voltage regulators.

The RS31390 is specifically optimized for these demanding applications by providing:

• Controlled startup and inrush current limiting
• Independent startup and steady-state current-limit control
• Adjustable short-circuit current limiting
• Fast short-circuit protection
• Overvoltage protection
• Overtemperature protection
• Selectable latch-off or auto-retry operation

Its 4V to 16V operating range makes it ideal for protecting intermediate bus and point-of-load rails powering GPUs, AI accelerators, CPUs, FPGAs, and ASICs.

PMBus Configuration and Real-Time Telemetry

The integrated PMBus interface transforms the RS31391 from a protection device into an intelligent power management solution.

Designers can remotely configure protection parameters while monitoring system operation through:

• Digital configuration of protection thresholds
• Precision current telemetry
• Fault reporting and diagnostics
• Power-good monitoring
• Device status reporting

These capabilities simplify system validation, accelerate fault isolation, and improve long-term reliability in AI and cloud computing platforms.

Scale Beyond 60A with More

As processor power continues to increase, power protection must scale accordingly.

The RS31391 supports 60A continuous and 80A peak current per device while operating in parallel with one or more companion devices to support significantly higher-current power rails.

This architecture allows designers to increase system current capability while maintaining a single PMBus interface for configuration, telemetry, and intelligent fault management.

Protect the Entire AI Power Architecture

The RS31391 is optimized for protecting intermediate bus and point-of-load power rails downstream of the IBC.

For protecting the upstream 48V power distribution rail, Reed Semiconductor offers the RS31512, a stackable PMBus-enabled eFuse designed specifically for front-end power protection.

Together, the RS31512 and RS31391 families provide intelligent, scalable protection across the complete AI power delivery chain—from the 48V distribution bus to the processor power rails.

Designed for AI Infrastructure

The RS31391 is ideal for:

• AI servers
• GPU accelerator platforms
• High-performance computing (HPC)
• Networking switches and routers
• PCIe accelerator cards
• FPGA and ASIC power rails
• Storage systems
• Telecom infrastructure
• Industrial computing platforms