Current Detection Circuit for Wide Voltage USB-PD Interfaces
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Solution Overview
Problem
Current detection schemes are limited in their voltage range and are not suitable for detecting the wide voltage range supported by USB-PD interfaces, such as 5V-20V, which hampers accurate current measurement.
Innovation Solution
A current detection circuit with a signal amplification branch, first and second voltage branches, and feedback branches is designed to generate amplified voltages and output signals that determine the current by adjusting feedback signals based on input voltages, allowing for stable output voltages across varying input voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a small detection resistor is added to the current path to form a voltage drop for amplification, then current detection can be realized, but the voltage range that can be supported is very limited
Solution Approach 1:
The patent divides the voltage input into two separate paths: a first voltage path that passes through the detection resistor for current measurement, and a second voltage path that provides a reference voltage. This segmentation allows the circuit to handle wide voltage ranges by comparing the detected voltage against a scalable reference, enabling USB-PD interface support (5V-20V) while maintaining detection accuracy through the amplified voltage difference signal.
2Measurement precision
If the detection resistor is used to generate voltage drop for current measurement, then current can be detected, but the output voltage becomes unstable when input voltage varies
Solution Approach 1:
The patent implements a feedback mechanism where the second voltage path provides a reference voltage that is scaled and fed back to compensate for input voltage variations. The amplifier compares the detected voltage from the first path with the reference from the second path, and the feedback loop adjusts the output to maintain stability. This ensures that even when input voltage changes across the USB-PD range, the output voltage remains stable and accurately represents the current measurement.
Data Source
AI summary
The current detection circuit includes a signal amplification branch, a first voltage branch, a second voltage branch and a first feedback circuit branch. The first feedback branch generates a feedback signal according to the first voltage generated by the first voltage branch, the second voltage and the first reference voltage generated by the second voltage branch. The signal amplification branch generates a first amplified voltage according to the first voltage and the feedback signal, and generates a second amplified voltage according to the second voltage and the feedback signal. The first voltage branch generates a first voltage and a first output voltage according to the first input voltage and the first amplified voltage. The second voltage branch generates a second voltage and a second output voltage according to the second input voltage and the second amplified voltage.