Voltage Converter IC with Integrated Bootstrap Capacitor

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Solution Overview

Problem

Existing switch-mode voltage regulators require external bootstrap capacitors due to their large size, which increases package size and reduces efficiency, as integrating these capacitors is challenging.

Innovation Solution

Integrating a pre-charge circuit and a bootstrap capacitor within the voltage converter IC to provide a bootstrap voltage signal for the high side switch, allowing for a smaller, more efficient bootstrap capacitor that can be integrated into the IC.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an external bootstrap capacitor is used, then the high voltage signal for driving the high side switch can be provided, but the package size increases and efficiency decreases

Engineering Contradiction:

Improvehigh voltage signal provisionVSAvoidpackage size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent integrates the bootstrap capacitor and pre-charge circuit directly into the voltage converter IC die, merging previously external components with the main circuit. This integration eliminates the need for external bootstrap capacitors, reducing package size while maintaining the high voltage signal generation capability for the high side switch.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The bootstrap capacitor is nested within the IC package, and the pre-charge circuit is integrated alongside it on the same die. This nesting approach allows the bootstrap function to be contained within the main IC, eliminating external components and reducing overall package size.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If an external bootstrap capacitor is used, then the high voltage signal can be provided, but the efficiency of the voltage regulator decreases

Engineering Contradiction:

Improvehigh voltage signal provisionVSAvoidefficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

By merging the pre-charge circuit and bootstrap capacitor into the IC, the patent reduces energy losses associated with external connections and component interactions. The integrated design minimizes parasitic elements and improves overall conversion efficiency while maintaining reliable high voltage signal provision.

Inventive Principle:

Principle #5Merging (Combining)

3Area of stationary object

If the bootstrap capacitor is integrated, then the package size is reduced, but the capacitor must be small in capacitance which challenges integration

Engineering Contradiction:

Improvepackage sizeVSAvoidintegration difficulty

Core Design Contradiction:

Area of stationary objectVSEase of manufacture

Solution Approach 1:

The patent segments the bootstrap function into two parts: a small integrated bootstrap capacitor and a pre-charge circuit. This segmentation allows the capacitor to be small enough for IC integration while the pre-charge circuit compensates for the reduced capacitance, achieving both size reduction and functional adequacy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pre-charge circuit performs preliminary charging action to prepare the bootstrap capacitor, enabling the small integrated capacitor to achieve the necessary voltage levels for high side switch operation. This preliminary action compensates for the smaller capacitance value.

Inventive Principle:

Principle #10Preliminary action

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 solution enables a compact and efficient switch-mode voltage regulator by eliminating the need for external bootstrap capacitors, reducing package size and improving efficiency while maintaining the necessary high voltage signal for the high side switch.

Implementation Method 1

The pre-charger is configured to provide a first bootstrap signal to pre-charge a control terminal of the high side switch

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the bootstrap capacitor is configured to provide a second bootstrap signal to enhance the charge of the control terminal of the high side switch

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS9917584B2Voltage converter integrated circuit with an integrated bootstrap capacitor

Publication Date: 2018.03.13 CHENGDU MONOLITHIC POWER SYST

AI summary

A bootstrap circuit integrated to a voltage converter integrated circuit (IC) and a voltage converter IC for a switch mode voltage regulator. The bootstrap circuit is used to provide a bootstrap voltage signal for driving a high side switch of the voltage converter IC. The bootstrap circuit has a pre-charger and a bootstrap capacitor. The pre-charger provides a first bootstrap signal to pre-charge a control terminal of the high side switch, and the bootstrap capacitor provides a second bootstrap signal to enhance the charge of the control terminal of the high side switch.