Switching Power Circuit Load Response via Node Voltage Sensing

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Solution Overview

Problem

Existing switching power circuits face challenges in accurately determining load states and smoothly switching phase compensation properties, leading to suboptimal load response properties and input variations.

Innovation Solution

A switching power circuit design that includes a sensing circuit to determine load states by sensing the voltage of a node before the switching transistor turns on, allowing for the selection of appropriate phase compensation circuits for light or heavy loads, thereby improving load response properties by switching the phase compensation circuit based on the load state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the phase compensation circuit properties are switched in accordance with load state, then load response properties are improved, but accurate determination of load state becomes difficult

Engineering Contradiction:

Improveload response propertiesVSAvoidload state determination accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent replaces direct current measurement with voltage sensing at the switching node. By measuring the voltage waveform characteristics (amplitude, frequency, duty cycle) at node SW instead of directly measuring load current, the system achieves accurate load state determination without complex current sensing circuits. This substitution enables precise load state detection that accurately reflects actual load conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces the switching node voltage as an intermediary parameter to determine load state. Instead of directly measuring load current or power consumption, the system uses the voltage at the switching node as a mediator that reflects load conditions. This intermediary voltage measurement provides accurate load state information that enables proper phase compensation switching.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If phase compensation circuit properties are switched, then load response properties are improved, but input variation with respect to error amplifier increases

Engineering Contradiction:

Improveload response propertiesVSAvoidinput variation at error amplifier

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by pre-charging the hold capacitor through the second switch before phase compensation switching occurs. This preliminary charging action ensures that the capacitor already has the appropriate voltage level ready, so when the switching occurs, there is minimal voltage variation at the error amplifier input. This pre-preparation eliminates abrupt transitions and maintains stability during phase compensation property switching.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent provides beforehand cushioning by using the hold capacitor to buffer voltage variations at the error amplifier input during phase compensation switching. The capacitor acts as a cushion that absorbs sudden voltage changes, preventing large input variations from reaching the error amplifier. This cushioning effect ensures smooth transitions when switching between different phase compensation configurations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS11290010B2Switching power circuit

Publication Date: 2022.03.29 KK TOSHIBA

AI summary

According to one embodiment, a switching power circuit, includes: a switching transistor that is connected between an input terminal and a node; a driving circuit that supplies a PWM driving signal to the switching transistor; and a phase compensation circuit that supplies a feedback voltage to an error amplifier, in which the properties of the phase compensation circuit are switched in accordance with the voltage of the node immediately before the switching transistor is turned on.