Switching Power Supply Control Circuit Using Analog Comparator
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Solution Overview
Problem
Current switching power supply control circuits face challenges in comparing detection values of current flowing into a switching regulator circuit with digital compensation values without using high-precision DACs, leading to oscillation of output voltage and reduced response precision.
Innovation Solution
A switching power supply control circuit that employs an I-V converter to convert output current into voltage, adds an offset voltage, and uses an analog comparator for comparison, with a second DAC generating the offset voltage and setting amplifier gain based on specific coefficients to enhance precision and reduce oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-precision DAC is used to convert digital compensation value to analog value for comparison with current detection value, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the parameters of the comparison system by using an analog comparator instead of a high-precision DAC. The current detection value is converted to voltage through an I-V converter, and both the current detection voltage and compensation voltage are directly compared in the analog domain, eliminating the need for high-precision digital-to-analog conversion while maintaining comparison accuracy
Solution Approach 2:
The patent replaces the digital conversion mechanism (DAC) with an analog comparison mechanism. Instead of converting digital compensation values to analog signals through a complex DAC, the system uses an analog comparator to directly compare the I-V converted current signal with the compensation voltage, substituting a simpler analog mechanism for a complex digital conversion process
2Measurement precision
If a high-precision DAC is used to convert digital compensation value to analog value, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive high-precision DAC components with cheaper analog components including an I-V converter and an analog comparator. These simpler, lower-cost components achieve the same functional goal of enabling precise current-compensation comparison without requiring expensive digital-to-analog conversion hardware
Solution Approach 2:
The patent changes the operational domain from digital conversion to analog comparison, using parameter transformations (current to voltage conversion) that can be achieved with simple, low-cost analog circuits rather than expensive high-precision DACs, thereby reducing manufacturing cost while maintaining measurement precision
3Device complexity
If simple control is used in voltage mode switching regulator, then device complexity is reduced, but manufacturing precision and stability deteriorate due to complicated phase compensation circuit
Solution Approach 1:
The patent introduces an analog comparator as an intermediary component that directly compares the I-V converted current signal with the compensation voltage. This intermediary enables precise control decision-making without requiring complex phase compensation circuits, achieving both simplicity and stability by mediating between the current detection and control output through straightforward analog comparison
4Device complexity
If analog comparator is used instead of high-precision DAC, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent substitutes the digital DAC mechanism with an analog comparison mechanism, where the I-V converter transforms the current detection value into a voltage that can be directly compared with the compensation voltage by the analog comparator. This substitution maintains precision by working in the analog domain where continuous voltage comparison preserves signal fidelity without digital quantization errors
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 allows for high-precision comparison and control of output current, reducing output voltage oscillation and improving response without requiring high-precision DACs, resulting in an inexpensive and effective current mode switching regulator.
Implementation Method 1
I-V converter configured to convert an output current flowing into the switching element to a voltage, the I-V converter multiplies the output current by a predetermined conversion coefficient to convert to an I-V conversion signal
Implementation Method 2
an offset voltage is added to the I-V conversion signal and amplified by an amplifier
Data Source
AI summary
A switching power supply control circuit has a switching element, a smoothing circuit, and a switching control circuit configured to control the switching element. The switching control circuit includes I-V converter configured to multiply an output current flowing into the switching element by a predetermined conversion coefficient and generating an I-V conversion voltage, an amplifier configured to amplify the sum of the I-V conversion voltage and an offset voltage and generating a current detection signal, a first DAC configured to convert a digital compensation value computed from an output voltage of the smoothing circuit to an analog converted value, a first analog comparator configured to compare the current detection signal with the analog converted value and generating a first comparison result signal, and a driver configured to control the switching element on the basis of the first comparison result signal.