Switch Control Circuit for Power Supply Current Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing output current estimating circuits are complex due to numerous components like resistors and capacitors, leading to estimation errors.
Innovation Solution
A switch control circuit that includes a sensing voltage detector, a low pass filter, and optional resistors or amplifying units to estimate output current by averaging detected sensing voltage during the discharging period of a power switch, using a rectification diode to generate an output current estimating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional output current estimating circuit uses multiple resistors, capacitors, and current sources, then the circuit can perform current estimation, but the circuit complexity increases and estimation errors occur due to component tolerances
Solution Approach 1:
The patent extracts only the essential function needed for current estimation by removing unnecessary components. Instead of using multiple resistors, capacitors, and current sources, the invention uses a single capacitor to integrate the sensing voltage, achieving current estimation with minimal components while maintaining accuracy and avoiding tolerance accumulation errors
Solution Approach 2:
The patent uses a current mirror circuit to copy the sensing current through transistors Q1 and Q2. This allows the output current to be estimated by measuring the voltage across a single resistor R1, rather than using multiple components in series or parallel configurations, thereby reducing complexity while preserving measurement capability
2Adaptability or versatility
If multiple components are used in the output current estimating circuit, then the circuit can handle various measurement requirements, but the manufacturing precision decreases due to cumulative tolerance errors
Solution Approach 1:
The patent reduces the number of components to the minimum necessary for accurate measurement. By using only one resistor R1 and one capacitor C1 along with standard transistors, the circuit eliminates cumulative tolerance errors that would occur with multiple resistors and capacitors, while still providing flexible current estimation through the adjustable RC time constant
Solution Approach 2:
The patent achieves versatility through parameter adjustment rather than component multiplication. The estimation accuracy and response characteristics can be tuned by changing the values of R1 and C1, or by adjusting the transistor parameters, without needing to add more components. This single-parameter-adjustment approach maintains manufacturing precision while providing measurement flexibility
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
The solution simplifies the estimation of output current with reduced errors, enabling precise control of the power switch operation based on the estimated current.
Implementation Method 1
a low pass filter which averages an input during a switching cycle of the power switch to generate the output current estimating voltage
Implementation Method 2
a rectification diode which rectifies a supplied current in accordance with a switching operation of the power switch to generate an output current
Data Source
AI summary
The power supply device includes a power switch, a rectification diode which rectifies a supplied current in accordance with a switching operation of the power switch to generate an output current, and a switch control circuit which averages a detected sensing voltage corresponding to a sensing voltage which follows a current which flows through the power switch to generate an output current estimating voltage corresponding to the output current.