DC/DC Converter Package With Separate Logic And Power Ground Terminals

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Solution Overview

Problem

The self turn-on phenomenon in non-isolated DC/DC converters, particularly in system-in-package configurations, leads to inefficiencies due to parasitic inductances and requires additional components or changes to the drive system to prevent.

Innovation Solution

The reference potential for the low-side pre-driver is taken from the logic ground instead of the main circuit, increasing the parasitic inductance between the low-side MOSFET and the reference potential without increasing the sum of inductances in the main circuit, thereby preventing self turn-on without adding new members or altering the drive system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the reference potential for the low-side pre-driver is taken from the main circuit, then the parasitic inductance between the low-side MOSFET and the reference potential is reduced, but self turn-on phenomenon occurs leading to energy loss

Engineering Contradiction:

Improveenergy lossVSAvoidself turn-on prevention

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent segments the ground reference system into two separate terminals: a power ground terminal (27) connected to the main circuit and a logic ground terminal (28) connected to the pre-driver. This segmentation allows the reference potential for the low-side pre-driver to be taken from the logic ground terminal instead of the main circuit, increasing parasitic inductance in the control path to prevent self turn-on while maintaining low inductance in the power path for efficient energy transfer.

Inventive Principle:

Principle #1Segmentation

2Reliability

If separate logic and power ground terminals are used, then self turn-on is prevented by increasing parasitic inductance in the reference path, but device complexity increases

Engineering Contradiction:

Improveself turn-on preventionVSAvoidpackage complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the separate logic ground terminal (28) and power ground terminal (27) into a single common ground point within the package structure. This merging approach maintains the functional separation needed for self turn-on prevention while simplifying the overall package design and reducing manufacturing complexity compared to completely separate ground systems.

Inventive Principle:

Principle #5Merging (Combining)

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 effectively prevents self turn-on and reduces losses in the DC/DC converter system by utilizing existing components and configurations, enhancing efficiency without additional hardware or system changes.

Implementation Method 1

increasing the parasitic inductance between the low-side MOSFET and the reference potential

Methodology Applied

Scientific EffectParasitic inductance: Parasitic Capacitance

Data Source

PatentUS8049479B2DC/DC converter package having separate logic and power ground terminals

Publication Date: 2011.11.01 RENESAS ELECTRONICS CORP

AI summary

In a non-isolated DC/DC converter, a reference potential for a low-side pre-driver which drives a gate of a low-side MOSFET is applied from a portion except for a main circuit passing through a high-side MOSFET and the low-side MOSFET so that a parasitic inductance between a source of the low-side MOSFET and the pre-driver is increased without increasing the sum of parasitic inductances in the main circuit and negative potential driving of the gate of the low-side MOSFET can be performed and a self turn-on phenomenon can be prevented without adding any member and changing drive system.