RS31321 - 5.5V/18V, 4.5A Dual-Input Power MUX with Priority Selection

RS31321 Compact Dual-Input Power MUX for Intelligent Power Path Management

The RS31321 is a dual-input, single-output Power MUX designed for seamless power-path selection between two different-voltage input sources. IN1 supports operation up to 5.5V, while IN2 supports operation up to 18V, making the device well suited for systems that select between a low-voltage source and a higher-voltage supply. The device supports up to 4.5A continuous output current and integrates back-to-back MOSFETs with low on-resistance of 40mΩ typical for IN1 and 64mΩ typical for IN2.

Packaged in a compact 2 × 2.5 mm VQFN-12 package, the RS31321 provides an efficient solution for modern multi-source power systems where both board space and power efficiency are critical.

Intelligent Dual-Input Power Selection

Many modern electronic systems operate from multiple power sources, including batteries, AC adapters, USB power, and redundant supply rails. The RS31321 automatically manages these inputs using programmable priority selection, ensuring the preferred source powers the load while enabling fast, seamless transitions whenever the primary source becomes unavailable.

Individual enable inputs provide additional system flexibility, allowing designers to implement custom startup sequencing, battery management, or application-specific power control strategies.

Fast source switchover minimizes output voltage droop, reducing the need for excessive output capacitance while maintaining uninterrupted operation of downstream circuitry.

Low-Power Performance for Space-Constrained Designs

The RS31321 combines efficient power path management with exceptionally low power consumption, making it well suited for portable and always-on systems.

Key performance advantages include:

• Wide 4V to 18V operating voltage range
• Up to 4.5A continuous output current
• Low 50mΩ integrated MOSFET resistance
• Low 330µA operating quiescent current
• Low 10µA shutdown current
• Fast source switchover with minimal output voltage disturbance

Together, these features help maximize system efficiency while extending battery runtime and reducing thermal dissipation.

Intelligent Monitoring and Power Management

The RS31321 integrates multiple control and monitoring functions that simplify system-level power management without requiring significant external circuitry.

Integrated management features include:

• Priority-based source selection
• Individual enable inputs
• Adjustable overcurrent protection
• Fault indication output

These integrated capabilities provide designers with greater flexibility for implementing intelligent power sequencing, fault reporting, and source management while reducing component count and PCB complexity.

Integrated Protection Improves System Reliability

The RS31321 incorporates comprehensive protection features that safeguard both the power sources and downstream electronics during abnormal operating conditions.

Integrated protection includes:

• Reverse current blocking using integrated back-to-back MOSFETs
• Fast reverse current detection and recovery
• Adjustable overcurrent protection
• Input undervoltage protection (UVP)
• Input overvoltage protection (OVP)
• Overtemperature protection
• Fault indication output

These protection features help improve overall system robustness while reducing the need for additional external protection circuitry.

Ideal for Battery-Powered and Embedded Applications

The RS31321 is optimized for applications requiring intelligent source selection, compact implementation, and low power consumption.

Typical applications include:

• Battery-powered equipment
• Portable electronics
• Battery management systems
• Embedded computing platforms
• Industrial control systems
• Telematics
• Surveillance systems
• Multiple power source applications
• Redundant and standby power systems

Its compact footprint and efficient operation make the RS31321 an excellent choice wherever reliable power path management and low standby power are essential.

Smart Power. Seamless Switching.

The RS31321 combines intelligent source selection, efficient power delivery, and comprehensive system protection in a highly integrated solution. By combining low-power operation, integrated reverse current blocking, fast source switchover, and robust fault protection, the device simplifies multi-source power system design while improving efficiency and reliability.

As part of Reed Semiconductor’s Power MUX family, the RS31321 provides a compact and efficient solution for battery-powered, embedded, industrial, and communications applications where intelligent power path management is critical.