High-Side Gate Driver Circuit for MOSFET Negative Voltage Protection
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Solution Overview
Problem
High-side gate drivers in motor vehicles experience negative voltage at the source and gate of power MOSFETs due to parasitic resistance and inductance, leading to uncontrolled currents and potential chip damage, necessitating additional current-limiting resistances that increase development costs.
Innovation Solution
A high-side gate driver design incorporating first and second current mirrors, N-channel transistors, switch circuits, and diodes, with the gate pin connected to an N-channel transistor electrically isolated from the substrate and a diode, allowing it to manage negative voltages without additional current-limiting resistances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current-limiting resistance is added between the gate pin of the high-side gate driver and the gate pin of the external MOSFET, then the negative voltage problem is solved, but the development cost increases
Solution Approach 1:
The patent combines the current-limiting function with the existing gate driver circuit by utilizing the body diode of the N-channel transistor and the inherent output impedance of the current mirror, eliminating the need for separate current-limiting resistors while maintaining negative voltage protection capability
Solution Approach 2:
The gate driver circuit uses its own internal components (body diode of N-channel transistor, output impedance of current mirror) to provide current limiting functionality, making the circuit self-sufficient without requiring external current-limiting resistors
2Reliability
If a current-limiting resistance is added to protect against negative voltage, then chip damage is prevented, but the circuit complexity increases
Solution Approach 1:
The body diode of the N-channel transistor acts as an intermediary element that provides current limiting protection during negative voltage conditions, while the output impedance of the current mirror serves as a natural current limiter, replacing the need for explicit current-limiting resistors
3Reliability
If additional current-limiting resistance is provided, then negative voltage management is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the current-limiting function into the existing gate driver transistor and current mirror circuit, eliminating the need for additional external current-limiting resistors and reducing component count for manufacturing
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
Enables effective management of negative voltages at the gate pin of power transistors without the need for additional current-limiting resistances, reducing development costs and preventing chip damage.
Implementation Method 1
an anode and a cathode of the first first-type diode (d1) are arranged to be connected to the source of the first N-channel transistor (Mn1) and a cathode of the second first-type diode (d2) respectively, an anode of the second first-type diode (d2) is arranged to be connected to an output end of the second current mirror (In1)
Implementation Method 2
first and second current mirrors (Ip1, In1), a first N-channel transistor (Mn1), first and second switch circuits
Implementation Method 3
the first N-channel transistor (Mn1), the second switch circuit and the second current mirror (In1) have a structure electrically isolated from a substrate
Data Source
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AI summary
The present invention provides a high-side gate driver, comprising: first and second current mirrors (Ip1, In1), a first N-channel transistor (Mn1), first and second switch circuits (Mp1, Mn2), first and second first-type diodes (d1, d2), and a first second-type diode (d3). The first switch circuit is arranged between an output end of the first current mirror and a source of the first N-channel transistor; the second switch circuit is arranged between a drain of the first N-channel transistor and an input end of the second current mirror. An anode and a cathode of the first first-type diode are arranged to be connected to the source of the first N-channel transistor and a cathode of the second first-type diode; an anode of the second first-type diode is arranged to be connected to an output end of the second current mirror; an anode and a cathode of the first second-type diode are arranged to be connected to ground and the cathode of the second first-type diode. Using the high-side gate driver, a negative voltage requirement of a transistor gate pin when electrified and not electrified can be met, with no need to additionally provide a current-limiting resistance.