Semiconductor Device Current Detection Accuracy
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Solution Overview
Problem
Current current detection circuits in electronic control units for vehicles face challenges in achieving accurate current detection due to increased circuit complexity and difficulties in maintaining desired current ratios during transition periods, which affects the precise control of solenoid valves and clutch operation.
Innovation Solution
The implementation of a semiconductor device with a current detector unit that includes sense transistors and a voltage monitor, which adjusts the duty ratio of pulse signals to improve current detection accuracy by shortening periods where current detection is less accurate, specifically by optimizing the transition periods between drive transistors and using auxiliary driver units to enhance monitoring and switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shunt resistor is used for current detection, then current detection accuracy is improved, but circuit scale increases
Solution Approach 1:
The patent uses a sense transistor to create a scaled-down copy of the driver transistor, where the sense transistor has a channel width that is a fixed ratio (e.g., 1/100) of the driver transistor's channel width. This copying approach allows current detection without requiring large shunt resistors, as the sense transistor replicates the driver's current characteristics in a miniaturized form, thereby maintaining detection accuracy while reducing circuit scale.
2Area of stationary object
If a sense transistor is used to detect current, then circuit scale is reduced, but current detection accuracy deteriorates during transition periods
Solution Approach 1:
The patent introduces a plateau period detection mechanism that identifies when the driver transistor is in a stable on-state (plateau period) versus transition periods. Current detection is performed only during the plateau period when the gate-source voltage is stable and the current ratio between driver and sense transistors is consistent. This preliminary identification of appropriate detection timing prevents inaccurate measurements during transition periods, thereby maintaining detection accuracy while using a compact sense transistor configuration.
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
This configuration enhances current detection accuracy by reducing the duration of plateau periods where current detection is challenging, thereby improving the control of solenoid valves and clutch operations, while preventing electromagnetic radiation noise.
Implementation Method 1
sense transistor channels Tr1 and Tr2 through which currents proportional to currents flowing through channels of drive transistors MN1 and MN2 flow, respectively
Data Source
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AI summary
A semiconductor device that can improve current detection accuracy is provided. According to one embodiment, an electronic control unit (a semiconductor device) includes: a drive transistor that controls current supply to a load; a current detector unit that detects a current of a sense transistor through which a current proportional to the current flowing through the drive transistor flows; a controller unit that generates a pulse signal with a duty ratio corresponding to the detection result of the current detector unit; a voltage monitor that monitors whether a voltage of an external output terminal has reached a battery voltage; and a pre-driver that performs charge and discharge to a control terminal of the drive transistor based on the pulse signal. Here, the pre-driver performs the charge and discharge to the control terminal of the drive transistor at a first charge and discharge speed, when the voltage of the external output terminal has not reached the battery voltage, and at a second charge and discharge speed faster than the first charge and discharge speed, when the voltage of the external output terminal has reached the battery voltage.