Bootstrap Diode Undervoltage Protection Circuit
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Solution Overview
Problem
The existing semiconductor device with a bootstrap diode system consumes excessive energy due to parasitic current flowing through the parasitic transistor PNPTr, and the methods to reduce this current, such as using a double diffusion layer, increase manufacturing costs and do not fully address energy consumption.
Innovation Solution
Incorporating a circuit load that can be turned off by an external signal, specifically a high-side power supply undervoltage protection circuit, to prevent steady-state current flow through the parasitic transistor PNPTr, thereby reducing energy consumption without requiring special manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a bootstrap diode is monolithically formed in the semiconductor device, then the need for a high-side floating power supply is eliminated, but parasitic current flows through the parasitic transistor PNPTr causing excessive energy consumption
Solution Approach 1:
The invention extracts and removes the parasitic current path by introducing a control circuit that detects and shuts down the bootstrap diode when parasitic conduction occurs. This isolates the harmful parasitic transistor PNPTr from the main circuit, preventing it from consuming excessive energy while maintaining the monolithic bootstrap diode structure.
Solution Approach 2:
The invention implements a feedback control mechanism where a control circuit continuously monitors the voltage relationship between VB and VCC terminals. When VB becomes lower than VCC (indicating parasitic conduction), the control circuit activates to turn off the bootstrap diode, thereby eliminating the parasitic current path and reducing energy consumption.
2Use of energy by moving object
If a double diffusion layer is formed to reduce parasitic current, then the parasitic current through PNPTr is reduced, but manufacturing cost and process complexity increase
Solution Approach 1:
Instead of modifying the physical structure through complex double diffusion processes, the invention introduces a control circuit as an intermediary element. This control circuit acts as a mediator that detects parasitic conduction conditions and actively manages the bootstrap diode operation, achieving parasitic current reduction without complicating the manufacturing process.
Solution Approach 2:
The invention changes the operational parameters of the bootstrap diode dynamically rather than altering its physical structure. By controlling the diode's on/off state based on voltage conditions (VB vs VCC), the system achieves parasitic current reduction through parameter management rather than structural modification, avoiding expensive double diffusion processes.
3Reliability
If the bootstrap diode operates continuously, then power is always available to the high-side drive circuit, but parasitic current causes continuous energy loss
Solution Approach 1:
The invention transforms the static, continuous operation of the bootstrap diode into a dynamic, condition-based operation. The diode switches between on and off states based on real-time voltage conditions, being active only when VB > VCC and automatically shutting off when parasitic conduction risk arises, thus eliminating continuous energy loss while maintaining power availability when needed.
Solution Approach 2:
The control circuit implements periodic monitoring of the voltage relationship between VB and VCC terminals, enabling the bootstrap diode to operate in controlled cycles rather than continuously. This periodic control ensures power availability during normal operation while preventing parasitic current during shutdown phases, reducing energy waste.
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 approach effectively decreases energy consumption by preventing parasitic current flow through the bootstrap diode, reducing manufacturing costs, and extending the device's lifespan.
Implementation Method 1
a bootstrap diode connected at its anode to the VCC terminal and at its cathode to the high side drive circuit and used to produce a VB potential serving as a power supply potential to the high side drive circuit
Implementation Method 2
The resulting voltage between the anode 200 and a p-substrate 208 causes a parasitic transistor PNPTr to conduct a current from the anode to the substrate
Data Source
AI summary
A semiconductor device includes, a high side drive circuit for controlling the high side power device and including a circuit load, a low side drive circuit for controlling the low side power device, a VCC terminal connected to the low side drive circuit and for supplying a VCC potential to the low side drive circuit, the VCC potential serving as a power supply potential to the low side drive circuit, a bootstrap diode connected at its anode to the VCC terminal and at its cathode to the high side drive circuit and used to produce a VB potential serving as a power supply potential to the high side drive circuit, and means for turning off the circuit load before the VB potential becomes lower than the VCC potential.