Switching Regulator Current Detection Circuit Using Inductor Waveforms
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Solution Overview
Problem
Current current detection circuits in switching regulators face limitations in accurately maintaining output current stability due to sampling constraints and increased chip size when using multiple current sampling circuits, which complicates integrated circuit design and requires additional peripheral components.
Innovation Solution
A current detection circuit that includes a feedback controlling circuit and a feedback signal generator, which receives the rise and fall times of inductor current to generate a feedback signal in direct proportion with the feedback control signal, allowing for indirect detection of output current and enabling precise control of power switches to maintain consistent output current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple current sampling circuits are used to improve detection accuracy, then measurement precision is improved, but device complexity increases and chip size increases
Solution Approach 1:
The patent segments the current detection function into two parts: using the existing feedback control circuit for voltage regulation while adding a separate feedback signal generator dedicated to current detection. This separation allows independent optimization of each function without increasing overall system complexity.
Solution Approach 2:
The feedback signal generator is designed to serve multiple purposes: it detects output current, provides current protection, and works with both synchronous and non-synchronous topologies. This multi-functionality eliminates the need for separate detection circuits for different operating modes.
2Measurement precision
If multiple current sampling circuits are used to improve detection accuracy, then measurement precision is improved, but area of stationary object increases
Solution Approach 1:
The patent merges the current detection function with the existing feedback control architecture by using the feedback signal generator to produce signals that are directly integrated into the control loop. This integration eliminates the need for separate peripheral components and reduces chip area.
Solution Approach 2:
The feedback signal generator uses the existing inductor current waveforms and feedback control signals as its input, essentially using the system's own operating signals for detection purposes. This self-service approach eliminates the need for external sensing components.
3Area of stationary object
If indirect detection method is used to reduce chip size, then area of stationary object is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the feedback signal generator continuously monitors the relationship between feedback control signals and inductor current waveforms, and adjusts the detection signal accordingly. This closed-loop approach ensures accurate current detection despite the indirect measurement method.
Solution Approach 2:
The patent uses the feedback control signal as an intermediary to translate the relationship between input voltage, inductor current, and output current into an accurate detection signal. This intermediary approach maintains measurement precision while avoiding direct output current sensing.
Data Source
AI summary
In one embodiment, a current detection circuit configured for a switching regulator can include: (i) a feedback controlling circuit configured to control a feedback signal to be consistent with a reference signal, and to generate a feedback control signal; and (ii) a feedback signal generator configured to receive a rise time and a fall time of inductor current of the switching regulator, and to generate the feedback signal in direct proportion with the feedback control signal.