Switching Converter Oscillator With Current-Limited Frequency Control

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Solution Overview

Problem

Existing switching converters face instability due to drastic changes in switching frequency when external adjustment resistors are short-circuited or open-circuited, leading to potential damage and reduced system stability.

Innovation Solution

Incorporating a charging current generating circuit with a current limiting module that limits the charging current to a preset value, using a variable resistor and transistors to stabilize the frequency by restricting the range of frequency variation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If frequency jitter technology is adopted to suppress electromagnetic interference, then electromagnetic compatibility is improved, but switching frequency stability deteriorates when external resistors are shorted or opened

Engineering Contradiction:

Improveelectromagnetic interferenceVSAvoidsystem stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the oscillator monitors the charging current through the variable resistor and automatically adjusts to maintain frequency within a safe range. When the resistor is shorted or opened, the feedback loop detects the abnormal condition and prevents drastic frequency changes, thus resolving the contradiction between EMI suppression and system stability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the operating parameters of the oscillator by introducing a variable resistor that can be adjusted to modify the charging current. This allows the system to adapt the switching frequency to different operating conditions while maintaining stability through the current limiting module, which constrains the frequency parameter within safe boundaries even when the resistor fails.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If external adjusting resistor is used to control oscillation frequency, then frequency adaptability is improved, but system reliability deteriorates when resistor is shorted or opened

Engineering Contradiction:

Improvefrequency adjustment rangeVSAvoidsystem stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-setting the current limiting module to define maximum and minimum current thresholds before operation. This preliminary configuration ensures that even if the external resistor fails, the oscillator frequency remains within predetermined safe boundaries, thus maintaining reliability while preserving frequency adaptability during normal operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The current limiting module serves as a protective cushion that is prepared in advance to prevent harmful effects. When the external resistor is shorted or opened, this pre-positioned protection mechanism immediately activates to limit the charging current and prevent drastic frequency changes, cushioning the system against the harmful effects of component failure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If charging current is not limited, then frequency adjustment flexibility is improved, but circuit damage risk increases when variable resistor is shorted or opened

Engineering Contradiction:

Improvefrequency variation rangeVSAvoidcircuit durability

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The current limiting module acts as an intermediary element between the power supply and the variable resistor. It mediates the charging current by imposing upper and lower limits, allowing flexible frequency adjustment when the resistor is within normal range while preventing excessive current that could damage the circuit when the resistor is shorted or opened.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Stabilizes the system by preventing drastic changes in switching frequency, enhancing stability and preventing damage when external resistors are faulty, thus improving overall system performance.

Implementation Method 1

a charging current generating circuit for generating a charging current; a clock signal generator circuit for generating a slope voltage according to the charging current

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the charging current generating circuit includes a variable resistor and a current limiting module, and the current limiting module is used for limiting a current value of the charging current to a preset current value

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentUS12438462B2Switching converter and oscillator thereof

Publication Date: 2025.10.07 SG MICRO CORP

AI summary

Disclosed are a switching converter and an oscillator thereof. The oscillator includes a charging current generating circuit and a clock signal generator circuit, which is used for generating a clock signal according to a charging current provided by the charging current generating circuit. The charging current generating circuit includes a variable resistor and a current limiting module. The current limiting module is used for limiting a current value of the charging current to a preset current value when the variable resistor is shorted or opened, thus avoiding drastic change of a switching frequency of the circuit when the external variable resistor is shorted or opened, so as to improve system stability.