Multi-Channel Current Sensing With One Op-Amp and Isolation Switches
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Solution Overview
Problem
Current sense circuits require multiple operational amplifiers for each channel, leading to increased physical size and complexity, as they need to detect currents flowing through multiple channels effectively.
Innovation Solution
The implementation of a current sense circuit with third-type switches that have bidirectional withstand voltage, allowing one operational amplifier to be shared across multiple channels, thereby suppressing interference between channels and reducing the physical size of the circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple operational amplifiers are used for each channel to detect currents effectively, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple current detection channels into a single operational amplifier circuit. The operational amplifier measures the voltage difference between the source terminals of multiple power switches, enabling simultaneous detection of currents across multiple channels through one shared component, thus reducing circuit complexity while maintaining detection precision
Solution Approach 2:
The operational amplifier is designed to serve multiple functions across different channels. By configuring the feedback circuit to accept voltage inputs from multiple power switch sources, a single operational amplifier performs the current detection function for all channels, making the component universal and eliminating the need for separate amplifiers for each channel
2Measurement precision
If multiple operational amplifiers are used for each channel, then measurement precision is improved, but the physical size of the circuit increases
Solution Approach 1:
Multiple detection channels are merged into a single operational amplifier circuit, significantly reducing the physical area required. Instead of having separate amplifiers occupying distinct spaces for each channel, the shared operational amplifier consolidates the detection function into one compact unit, directly reducing the overall circuit footprint
3Device complexity
If one operational amplifier is shared across multiple channels, then device complexity is reduced, but interference between channels may increase
Solution Approach 1:
The feedback circuit is configured with channel-specific voltage input points that tap into the source terminals of individual power switches. This local quality approach ensures that each channel's voltage signal is independently captured at its specific location, preventing cross-channel interference while still using the shared operational amplifier for measurement
Data Source
AI summary
A current sense circuit includes channels a detection terminal, a feedback circuit and third-type switches. The channels respectively have first-type switches and second-type switches. Each of the first-type switches supplies an electric power to a load when the first-type switch is turned on. The second-type switches are respectively connected to the first-type switches in parallel, and respectively detect currents flowing through the first-type switches. The detection terminal is connected to the second-type switches. The feedback circuit includes a single operational amplifier having a first input terminal and a second input terminal. The first input terminal is connected to respective electrodes of the first-type switches close to the load. The second input terminal is connected to respective electrodes of the second-type switches close to the detection terminal. The third-type switches are connected to the electrodes of the first-type switches and the first input terminal.