Integrated SMPS Controller Multiplexing Pin for Peak Current Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing switch mode power supplies face inaccuracies in peak current detection due to signal transfer delays and circuit delays, leading to adverse control effects and increased complexity, which complicates chip minimization and increases production costs.
Innovation Solution
An integrated switch mode power supply controller with a multiplexing pin that operates in a switching cycle with three time intervals, where the detection voltage signal is proportional to the DC input voltage, output voltage, and voltage across the power transistor, allowing for current compensation and quasi-resonant switching to accurately control the power transistor and reduce electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional peak current detection methods are used, then the power supply can operate, but detection accuracy is poor due to signal transfer delays and circuit delays
Solution Approach 1:
The patent introduces an auxiliary winding on the transformer as an intermediary element to detect peak current. This auxiliary winding provides a direct magnetic coupling path that bypasses the problematic signal transfer delays through the power transistor and control circuit, enabling accurate peak current detection without the delays that compromise control accuracy.
Solution Approach 2:
The patent replaces the electrical signal-based current detection method (which suffers from delays) with a magnetic field-based detection method using the auxiliary winding. By detecting the voltage induced in the auxiliary winding that is proportional to the peak current, the system eliminates the signal transfer delays inherent in traditional electrical measurement paths.
2Adaptability or versatility
If multiple separate circuits are used for current detection, voltage regulation, and protection, then each function can be implemented, but device complexity increases and chip size grows
Solution Approach 1:
The auxiliary winding serves multiple functions: it detects peak current for accurate timing control, provides overvoltage protection by detecting abnormal voltage conditions, and enables quasi-resonant switching operation. This single multi-functional element replaces what would otherwise require separate circuits for each function, reducing chip size while maintaining full functionality.
Solution Approach 2:
The patent merges the functions of current detection, voltage regulation, and protection circuits into a unified control approach centered around the auxiliary winding signal. By combining these functions that share common requirements and can operate from the same detection source, the overall device complexity is reduced while maintaining adaptability.
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 enhances the accuracy of peak current detection, reduces electromagnetic interference, and minimizes chip size and production costs by enabling quasi-resonant switching and overvoltage protection, while maintaining constant output voltage.
Implementation Method 1
during the first time interval, the detection voltage signal is proportional to the DC input voltage... during the second time interval, the detection voltage signal is proportional to an output voltage of the switch mode power supply... during the third time interval, the detection voltage signal is proportional to a voltage across a power transistor
Implementation Method 2
Existing switch mode power supplies face inaccuracies in peak current detection due to signal transfer delays and circuit delays
Implementation Method 3
signal transfer delays and circuit delays
Implementation Method 4
The main transistor of a switching-mode supply can switch between on and off states at a given operating frequency, and voltage regulation can be achieved by varying the ratio of the on-to-off time of the main transistor
Implementation Method 5
a current compensation signal is configured to be generated according to the detection voltage signal to obtain a peak current flowing through an inductor in the switch mode power supply
Data Source
AI summary
In one embodiment, an integrated switch mode power supply controller can include: a multiplexing pin that receives a detection voltage signal; a switch mode power supply that receives a DC input voltage, and operates in a switching cycle having first, second, and third time intervals; during the first time interval, the detection voltage signal is proportional to the DC input voltage, and a current compensation signal is generated according to the detection voltage signal to obtain a peak inductor current; during the second time interval, the detection voltage signal is proportional to an output voltage of the switch mode power supply, and a discharging duration of current through the inductor is determined based on the detection voltage signal; and during the third time interval, the detection voltage signal is proportional to a voltage across a power transistor of the switch mode power supply.