DC-DC Converter Test Loop for Fast Feedback Calibration
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Solution Overview
Problem
Existing methods for testing and calibrating DC-DC converters are complex, costly, and often result in unstable operation due to noise and excessive testing time, especially when dealing with multiple outputs.
Innovation Solution
The implementation of a switching DC-DC converter circuit with a test loop circuitry that allows for calibrating the feedback loop during the testing phase, enabling faster and more precise trimming of the converter's output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closed-loop architecture is implemented on the automatic test board to measure DC-DC converter accuracy during testing, then the converter can operate in normal regulation mode, but the complexity and cost of the test board increases and stability issues may occur due to board parasitic effects
Solution Approach 1:
The patent extracts the inductor component from the DC-DC converter circuit during testing, allowing the converter to operate in open-loop pulse-skip mode. This eliminates the need for a complex closed-loop test board architecture while maintaining the ability to measure converter accuracy. The inductor is temporarily removed or disconnected during the testing phase, simplifying the test setup.
Solution Approach 2:
The patent changes the operating parameters of the DC-DC converter by forcing a ramp voltage signal at the output node, which causes the converter to operate in pulse-skip mode rather than continuous regulation mode. This parameter change allows for simplified testing without requiring complex test board infrastructure, as the converter's switching behavior becomes predictable and measurable under these specific conditions.
2Measurement precision
If a long-time average is applied to filter output voltage ripple for precise measurement, then measurement precision improves, but the testing time becomes excessively long
Solution Approach 1:
The patent changes the converter's operating mode to pulse-skip mode by applying a ramp voltage signal, which produces a predictable switching pattern. This allows for faster measurement techniques that do not require long-time averaging, as the switching node behavior becomes periodic and easier to analyze within a shorter time frame, thus reducing testing time while maintaining measurement precision.
Solution Approach 2:
The patent utilizes the periodic switching action that occurs in pulse-skip mode when a ramp voltage is applied. The converter switches at predictable intervals, creating a periodic signal that can be measured and analyzed more quickly than continuous ripple filtering. This periodic behavior enables precise measurements without requiring excessively long testing durations.
3Adaptability or versatility
If the converter is operated in pulse-skip condition with a ramp voltage applied at the output, then the testing method becomes applicable and measurement is simplified, but the method is not applicable to DC-DC converters operating in forced continuous conduction mode
Solution Approach 1:
The patent introduces dynamic control by applying a programmable ramp voltage signal with adjustable slope and amplitude to the output node. This dynamic approach allows the testing method to adapt to different converter types and operating modes. By dynamically adjusting the ramp parameters, the method can force converters into pulse-skip mode for testing, or accommodate converters that naturally operate in continuous conduction mode, thereby improving versatility while maintaining reliability.
Data Source
AI summary
A switching DC-DC converter circuit includes a switching stage having an input node receiving an input voltage and an output node producing an output voltage. The converter includes feedback loop circuitry coupled to the output node of the switching stage to produce, at a respective output node, a control signal of the converter circuit as a function of a difference between the output voltage and a reference voltage. The converter includes test loop circuitry arranged between an output node of the feedback loop circuitry and the output node of the switching stage. The test loop, when enabled, sources a current to the output node of the switching stage or sinks a current from the output node of the switching stage as a function of a value of the control signal of the converter circuit. The feedback loop circuitry is calibrated during a test phase of the switching DC-DC converter circuit.