Load Drive Current Sensing Layout for Stable Sense Ratios
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Solution Overview
Problem
Load drive devices with semiconductor elements and current detection resistors face issues with gate voltage dependence in sense ratios, leading to fluctuations in current detection accuracy, which existing configurations struggle to mitigate without increasing body size.
Innovation Solution
The proposed load drive device design includes a semiconductor element with a wider interval between its main and sense elements, allowing for lower drift resistance in the sense element compared to the main element, and a current detection resistor with a resistance value set to satisfy specific conditions, thereby canceling the influence of the current detection resistor and suppressing gate voltage dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the current detection resistor is connected between the second main electrodes of the main element and sense element, then current detection is enabled, but gate voltage dependence causes sense ratio fluctuations
Solution Approach 1:
The patent changes the resistance value of the current detection resistor to a specific range (0.1Ω to 10Ω) to optimize the balance between detection accuracy and gate voltage dependence. Additionally, the interval between the main element and sense element is adjusted to control drift resistance, thereby stabilizing the sense ratio across different gate voltages while maintaining accurate current detection.
Solution Approach 2:
The patent creates a localized region with controlled drift resistance by adjusting the interval between the main element and sense element. This local structural modification allows the sense element to have different drift characteristics compared to the main element, compensating for gate voltage effects and stabilizing the sense ratio in that specific region.
2Reliability
If the interval between main element and sense element is increased to reduce drift resistance, then sense ratio stability improves, but device body size increases
Solution Approach 1:
The patent optimizes the interval between the main element and sense element to a specific range that provides sufficient drift resistance reduction for sense ratio stability while maintaining a compact device footprint. This parameter optimization allows the device to achieve reliable current detection without excessive size increase.
Data Source
AI summary
A load drive device includes a semiconductor element and a current detection resistor. The semiconductor element includes a first main electrode provided on a front surface side and having a higher potential and a second main electrode provided on a back surface side opposite to the front surface and having a lower potential than the first main electrode. The second main electrode is divided such that the semiconductor element includes a main element that supplies electric power to a load in response to the main element being turned on and a sense element that detects a current. The current detection resistor is connected in series to the sense element and provided between the second main electrode of the sense element and the second main electrode of the main element.