Hot Swap Controller With Individual MOSFET Current Paths

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional hot swap controllers lack sufficient individual control over MOSFETs due to manufacturing and process variations, leading to overdesign and increased costs and inefficiencies to account for worst-case scenarios.

Innovation Solution

A hot swap controller with multiple parallel current paths and individual control logic for each MOSFET, allowing for independent control of gate voltages to manage inrush current and voltage, ensuring all MOSFETs concurrently conduct current, thereby reducing the safe operating area requirements and enabling the use of smaller, lower-cost MOSFETs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional hot swap controllers use multiple MOSFETs to handle large inrush current, then the controller can manage high current and power consumption, but individual control of MOSFETs is insufficient due to manufacturing tolerances and process variations, leading to overdesign and increased cost

Engineering Contradiction:

Improveinrush current handling capabilityVSAvoidoperational consistency

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent divides the single control function into multiple independent control paths, with each MOSFET having its own dedicated control circuit. This segmentation allows individual optimization and control of each MOSFET, compensating for manufacturing variations and preventing overdesign while maintaining reliable operation at high power levels.

Inventive Principle:

Principle #1Segmentation

2Power

If conventional hot swap controllers use multiple MOSFETs to handle large inrush current, then the controller can manage high current and power consumption, but overdesign is required to account for worst case scenarios, resulting in added cost

Engineering Contradiction:

Improveinrush current handling capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

By segmenting the control function into individual MOSFET control circuits, each MOSFET can be sized optimally for its specific role rather than requiring all MOSFETs to be oversized for worst-case scenarios. This reduces component costs while maintaining the ability to handle high inrush current through coordinated operation of multiple smaller, cheaper MOSFETs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent dynamically adjusts control parameters (gate voltages) for each MOSFET based on real-time operating conditions and individual MOSFET characteristics. This allows the system to adapt to manufacturing variations without requiring conservative overdesign, thereby reducing component specifications and costs while maintaining reliable high-power operation.

Inventive Principle:

Principle #35Parameter changes

3Power

If conventional hot swap controllers use multiple MOSFETs to handle large inrush current, then the controller can manage high current and power consumption, but operational inefficiency occurs due to lack of individual MOSFET control

Engineering Contradiction:

Improveinrush current handling capabilityVSAvoidoperational efficiency

Core Design Contradiction:

PowerVSProductivity

Solution Approach 1:

The patent segments the control function into individual MOSFET control circuits, enabling each MOSFET to operate at optimal efficiency points. This allows the system to distribute current dynamically across multiple MOSFETs based on their individual characteristics and operating conditions, improving overall operational efficiency while maintaining high power handling capability.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for more efficient management of inrush current, reducing the power dissipation and cost of MOSFETs, while ensuring safe operation and a shorter inrush phase, by ensuring all MOSFETs operate within a safe operating area, thus improving operational efficiency and reducing costs.

Implementation Method 1

A hot swap controller monitors input voltage and limits inrush current by adjusting gate voltages of metal oxide semiconductor field effect transistors (MOSFETs)

Methodology Applied

Scientific EffectField effect transistor (MOSFET) operation:

Implementation Method 2

Each current path respectively provides a sense output to indicate current in the path

Methodology Applied

Scientific EffectElectrical conduction measurement: Conduction (electrical)

Data Source

PatentUS9917437B2Hot swap controller with individually controlled parallel current paths

Publication Date: 2018.03.13 CISCO TECHNOLOGY INC

AI summary

An apparatus comprises an input node, a power rail to power a circuit load, and multiple current paths coupled in parallel with each other between the input node and the power rail. Each current path respectively provides a sense output to indicate current in the path and a current switch having a control input to control the current in the path. A control circuit, coupled to each control input individually and to each sense output individually, controls the current in each path individually based on the indicated current therein after a non-zero input voltage is initially applied to the input node, such that all of the paths concurrently conduct current from the input node to the power rail and collectively cause a total inrush current and corresponding voltage at the power rail to gradually increase.