RS31387 4V to 16V, 50A Stackable eFuse with Auto-Retry Protection and Current Monitoring

High-performance servers, networking equipment, storage systems, and industrial automation platforms require power protection solutions that not only safeguard valuable electronics but also maximize system uptime. In applications where temporary faults are expected or unattended operation is essential, automatic recovery can significantly improve system availability and reduce maintenance requirements.

The RS31387 is a fully integrated 50A stackable eFuse that combines a low 0.8mΩ power MOSFET, programmable hot-swap protection, precision current monitoring, and automatic fault recovery into a compact 5 × 5 mm LGA package. Operating from 4V to 16V, the RS31387 supports standalone operation or parallel configurations for substantially higher current applications, making it an ideal front-end protection solution for modern AI servers, networking equipment, enterprise storage, and industrial computing platforms.

Unlike traditional latch-off protection devices, the RS31387 automatically attempts to restore power after a fault has cleared, improving system uptime while maintaining comprehensive protection against overloads, short circuits, overvoltage, and overheating.

---

Optimized for High-Availability Systems

The RS31387 is specifically designed for applications where maintaining continuous operation is critical.

Typical applications include:

• AI accelerator cards
• Enterprise servers
• Networking switches and routers
• Telecommunications infrastructure
• Enterprise storage systems
• PCIe accelerator cards
• Industrial automation equipment
• Embedded computing platforms

Its integrated architecture provides high-current protection while reducing component count, PCB area, and overall design complexity.

---

Fully Integrated 50A Power Protection

The RS31387 integrates a low 0.8mΩ power MOSFET capable of supporting 50A continuous load current, eliminating the need for large external MOSFETs.

Benefits include:

• Reduced PCB footprint
• Lower BOM cost
• Improved efficiency
• Reduced conduction losses
• Simplified layout
• Better thermal performance

An adjustable soft-start function minimizes inrush current during hot-plug events, protecting connectors, power supplies, and downstream loads.

---

Automatic Fault Recovery

The defining feature of the RS31387 is its auto-retry fault response.

When a temporary fault occurs, the device disconnects the load to protect the system. Once the fault condition is removed, the RS31387 automatically restarts the output without requiring manual intervention or a system reset.

This behavior is particularly valuable for:

• Remote infrastructure
• Industrial automation
• Networking equipment
• Telecom systems
• Enterprise storage
• High-availability servers

By automatically recovering from transient events, the RS31387 helps maximize uptime while maintaining robust system protection.

For applications where faults should remain isolated until manually reset, Reed Semiconductor also offers the RS31385, which features latch-off fault protection.

---

Comprehensive Analog Protection

The RS31387 integrates multiple programmable protection mechanisms, including:

• Adjustable overcurrent protection
• Adjustable short-circuit current limit
• Fast-trip short-circuit protection
• Input overvoltage protection
• Overtemperature protection
• Input-to-output short-circuit detection
• Fault indication outputs
• Fault type reporting

These configurable protection features allow designers to optimize system behavior for a broad range of applications while maintaining reliable operation under dynamic load conditions.

---

Accurate Current Monitoring

The integrated analog current monitor provides continuous visibility into system load current without requiring external current-sense amplifiers.

This enables:

• Load monitoring
• Fault diagnostics
• Power budgeting
• Thermal management
• Predictive maintenance

The analog interface provides a straightforward monitoring solution while keeping system complexity low.

---

Scalable for Higher Current Designs

The RS31387 can operate as a standalone 50A protection device or be connected in parallel with additional RS31387 devices to support significantly higher current applications.

Its active current-sharing architecture allows designers to increase output current while maintaining coordinated protection across multiple devices, providing a scalable solution for next-generation AI, server, and networking platforms.

---

Migration Path to Intelligent Digital Power Management

For applications requiring digital configuration, PMBus telemetry, remote diagnostics, and system-level control, Reed Semiconductor also offers the RS31380 intelligent eFuse.

The RS31380 builds on the same integrated protection architecture by adding:

• PMBus® 1.3 interface
• Real-time voltage, current, power, and temperature telemetry
• Remote configuration
• Fault logging
• System diagnostics

While the RS31387 and RS31380 use different pinouts and are not pin-compatible, they address similar high-current applications and provide complementary solutions for analog and digital power management.

---

Why Choose the RS31387?

The RS31387 combines a 50A integrated eFuse, 0.8mΩ power MOSFET, automatic fault recovery, accurate current monitoring, and parallel scalability into a compact solution for modern high-current power systems. Its auto-retry protection maximizes system uptime by automatically restoring operation after temporary faults, making it an ideal choice for servers, networking equipment, telecommunications infrastructure, enterprise storage, and industrial systems where uninterrupted operation is essential.

---

Family Summary

• RS31385 → Fixed latch-off protection
• RS31386 → Selectable latch-off, configurable auto-retry, or follower mode
• RS31387 → Fixed auto-retry protection
• RS31380 + RS31385/86 → Adds PMBus configuration, telemetry, and digital monitoring