Power Transistor Current Sensing With Shared Overcurrent Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor devices face challenges in miniaturization due to the large occupied area of detection circuits for detecting current in power devices, which are compounded by issues in accurately detecting overcurrents during short circuits to ground or power supply.
Innovation Solution
A semiconductor device configuration that integrates high-side and low-side detection circuits with shared sense transistors and detection circuits, utilizing operational amplifiers for feedback control to equalize source or drain voltages, and includes an over-range comparison circuit to generate abnormal signals, thereby reducing the occupied area and enhancing overcurrent detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate detection circuits are used for high-side and low-side current detection, then detection accuracy is improved, but occupied area increases
Solution Approach 1:
The patent combines high-side and low-side detection circuits into a single integrated detection circuit. The sense transistor is shared between both detection modes, and the operational amplifier serves dual purposes for both high-side and low-side voltage comparisons. This merging reduces the occupied area while maintaining detection accuracy through selective activation of detection modes.
Solution Approach 2:
The detection circuit dynamically switches between high-side detection mode and low-side detection mode based on operating conditions. Switching elements selectively connect the sense transistor and operational amplifier to different circuit configurations, enabling the same hardware to adaptively serve both detection purposes without requiring separate dedicated circuits for each mode.
2Area of stationary object
If detection circuit area is reduced for miniaturization, then device size is decreased, but overcurrent detection accuracy during short circuits deteriorates
Solution Approach 1:
The detection circuit is segmented into distinct functional blocks: a sense transistor for current sensing, an operational amplifier for voltage comparison, switching elements for mode selection, and separate detection circuits for high-side and low-side operations. This segmentation allows efficient space utilization while maintaining dedicated functional paths for accurate overcurrent detection during short circuit conditions.
Solution Approach 2:
The operational amplifier acts as an intermediary that compares voltages from the sense transistor against reference voltages to detect overcurrent conditions. During short circuits, the switching elements activate specific pathways that ensure the operational amplifier receives appropriate voltage signals for accurate overcurrent detection, even when the detection circuit occupies minimal area.
3Measurement precision
If feedback control is implemented to equalize voltages, then current detection accuracy is improved, but device complexity increases
Solution Approach 1:
The operational amplifier implements feedback control by comparing the voltage across the sense transistor with a reference voltage and adjusting the gate voltage of the sense transistor to equalize the voltages. This feedback mechanism ensures accurate current detection by maintaining proper voltage alignment between the sense transistor and the load, improving measurement precision through automatic voltage balancing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed configuration effectively suppresses the increase in occupied area while enabling accurate detection of overcurrents, ensuring reliable operation and miniaturization of the semiconductor device.
Implementation Method 1
feedback controlling with an operational amplifier (13) so that the voltage of node (11) (source voltage of sense transistor 7) becomes the same as the voltage of node (5) (source voltage of high-side transistor 2), thereby aligning the gate-source voltage and drain-source voltage of the high-side transistor (2) and the sense transistor (7)
Implementation Method 2
Detection technology for detecting the current flowing through a power device is shown, for example, in Patent Documents 1 to 3
Data Source
AI summary
To provide a semiconductor device that can be miniaturized. The semiconductor device includes a power transistor H_PN, L_PN that supplies current to a load, a current detection circuit that detects the current flowing through the power transistor H_PN, L_PN, a first detection current H_DI1, L_DI1 based on the current detected by the current detection circuit, a device control circuit that controls the current flowing through the power transistor H_PN, L_PN based on an input signal Inp, an overrange comparison circuit that outputs an overrange signal H_OV, L_OV when the voltage of the power transistor H_PN, L_PN exceeds a predetermined voltage,, and an abnormal signal generation circuit that outputs an abnormal signal indicating an overcurrent state of the power transistor based on a second detection current H_DI2, L_DI2 detected by the current detection circuit and the overrange signal H_OV, L_OV.