High-Side Driver Spurious Turn-On Prevention via N-Epi Sensing
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Solution Overview
Problem
The existing gate driver technologies fail to prevent spurious turn-on at the high-side gate driver output due to N− epi P-sub diode conduction during negative transient voltage, caused by parasitic inductive and current transients.
Innovation Solution
A high-side driver circuit is designed with complementary MOSFETs and a parasitic bipolar transistor, incorporating a P-Zener ring and resistance to sense negative voltage at the epitaxial region, preventing conduction by providing a signal to control the MOSFETs and maintaining the high-side power switching device in an off state during negative transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high-side driver circuit is used to drive power switching devices, then the switching performance and power control capability are improved, but spurious turn-on occurs at the high-side gate driver output due to N-epi P-sub diode conduction during negative transient voltage
Solution Approach 1:
The sensing circuit detects negative transient voltage at the N+ epitaxial region before the parasitic transistor can cause spurious turn-on. By performing preliminary detection and triggering the prevention circuit in advance, the system blocks the harmful conduction before it occurs, maintaining both switching performance and reliability
Solution Approach 2:
A sensing circuit acts as an intermediary between the power switching circuit and the control logic. The sensing circuit monitors the voltage at the N+ epitaxial region and triggers the prevention circuit when negative transient is detected, mediating the interaction between the power circuit and control system to prevent spurious turn-on
2Adaptability or versatility
If parasitic inductive and current transients are present in the circuit, then the circuit can handle dynamic switching operations, but negative transient voltage causes N-epi P-sub diode conduction and spurious turn-on
Solution Approach 1:
The sensing circuit utilizes the negative transient voltage itself as the trigger signal for prevention. When the harmful negative transient occurs, it directly triggers the sensing circuit which then activates the prevention mechanism, converting the harmful voltage excursion into a useful trigger signal for protection
Solution Approach 2:
The prevention circuit applies counter-action by blocking the gate drive signal when negative transient is detected. The circuit actively prevents the spurious turn-on by inhibiting the gate driver output, applying anti-action to counteract the harmful effect of the parasitic transistor conduction
3Device complexity
If no sensing circuit is implemented, then the device complexity is reduced, but spurious turn-on cannot be detected and prevented
Solution Approach 1:
The sensing circuit is implemented locally at the N+ epitaxial region where the negative transient voltage first occurs. By placing the sensing function at this critical local point, the system achieves reliable detection with minimal additional complexity, focusing protection where it is most needed
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 solution effectively prevents spurious turn-on of the high-side driver, avoiding short circuit currents and potential damage by sensing and managing negative transients, ensuring reliable operation during voltage fluctuations.
Implementation Method 1
a second circuit coupled to the diffusion for sensing the high-side driver supply voltage at the epitaxial region
Implementation Method 2
the parasitic transistor will conduct a short circuit current between the switched node and the substrate
Data Source
AI summary
A high-side driver in a driver circuit for driving a half-bridge stage having high- and low-side power switching devices series connected at a switched node, the high-side driver driving the high-side power switching device. The high-side driver including first and second complementary switched MOSFET series connected at a high-side node, driving the high-side power switching device, one of the MOSFETs having a parasitic bipolar transistor formed between the substrate, an N+ epitaxial region connected to the high-side driver supply voltage and the switched node, with the parasitic transistor having a base electrode formed by the N+ epitaxial region, an emitter electrode formed by the substrate and a collector electrode formed by the switched node, such that if a transient voltage that is negative with respect to the substrate is present at the high-side driver supply voltage, the parasitic transistor will conduct a short circuit current between the switched node and the substrate; a first circuit for controlling the conduction of the first and second MOSFETs to switch the high-side switching device ON and OFF; a diffusion in the N+ epitaxial region in which a terminal connected to the switched node is provided by the diffusion forming the collector of the parasitic transistor; and a second circuit coupled to the diffusion for sensing the high-side driver supply voltage at the epitaxial region and providing a signal to the first circuit to prevent turn-ON of the high-side power switching device.