Switching Power Converter Current Feedback Pin Reduction
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Solution Overview
Problem
Conventional switching power converters require a large sampling resistor and additional pins for current feedback, complicating the control circuit and increasing design difficulties when aiming for a constant current output.
Innovation Solution
A control circuit with a valley-value obtaining circuit, peak-value obtaining circuit, and compensation signal generating circuit is used to control power stage transistors, allowing for constant current control by sampling electric currents through these transistors, eliminating the need for a sampling resistor and reducing the number of pins required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional switching power converter uses an inductor coupled in series with a sampling resistor for current feedback, then current sampling can be achieved, but the sampling resistor requires large resistance and additional pins are needed in the control circuit
Solution Approach 1:
The patent extracts the current sampling function from the conventional series sampling resistor configuration and relocates it to the control circuit's internal current detection unit. This allows the sampling resistor to be eliminated or significantly reduced in value, thereby reducing the number of external pins required while maintaining current sampling accuracy through the integrated detection mechanism
Solution Approach 2:
The patent merges the current sampling function with the control circuit's internal structure by integrating a current detection unit that can measure inductor current without requiring an external sampling resistor. This consolidation eliminates the need for separate sampling components and reduces the overall pin count of the control circuit
2Reliability
If a conventional switching power converter uses an inductor coupled in series with a sampling resistor, then current feedback is available, but the circuit requires more pins and has increased design difficulty
Solution Approach 1:
The patent combines multiple functions (current sampling, current detection, and control) into a single integrated control circuit. The current detection unit is integrated within the control circuit to detect inductor current directly, eliminating the need for external sampling resistors and reducing design complexity while maintaining reliable constant current control
Solution Approach 2:
The control circuit is designed with multi-functionality, incorporating both the control functions and the current detection functions within a single integrated unit. This universal design allows the control circuit to perform multiple tasks without requiring additional external components, thereby simplifying manufacturing and reducing design difficulty
Data Source
AI summary
The present disclosure relates to a switching power converter, a control circuit and an integrated circuit therefor, and a constant-current control method. The control circuit samples a valley value of an electric current through a first power transistor in a power stage circuit and a peak value of an electric current through a second power transistor in the power stage circuit, and obtains parameters representing an output current in accordance with an average value of the valley value and peak value. Thus, the constant-current control can be performed by sampling the electric current through the first power transistor and the second power transistor. Moreover, the switching power converter simplifies a current feedback loop for outputting a constant current, and the integrated circuit has fewer pins.