Semiconductor Power Element Gate Control via Parasitic Capacitance Pre-Charging
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Solution Overview
Problem
Conventional semiconductor devices for power control, such as bridge circuits, suffer from complex circuit configurations and miss-operation due to parasitic capacity issues, leading to short-circuits and gate voltage fluctuations.
Innovation Solution
A semiconductor device with a simple circuit configuration featuring a first and second power element totem-pole-connected, driven by separate high-voltage and low-voltage driving circuits, and a switching element connected between the high-voltage terminal and a resistor, which prevents miss-operation by controlling the gate voltage of the power elements without requiring a negative power source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional semiconductor device uses a power element with parasitic capacity, then the device can achieve basic power control function, but gate voltage fluctuation occurs causing miss-operation and short-circuit
Solution Approach 1:
The invention applies preliminary anti-action by pre-charging the parasitic capacity Cres through a dedicated charging circuit before the power element Q1 turns ON. This pre-charging action counteracts the harmful dV/dt effect that would otherwise cause gate voltage fluctuation and potential miss-operation of the complementary power element Q2, thereby preventing the harmful effect before it occurs.
Solution Approach 2:
The invention introduces an intermediary charging circuit comprising a charging transistor Q4 and resistor R1 that mediates the charge transfer to the parasitic capacity Cres. This intermediary circuit isolates the harmful dV/dt effect from directly affecting the gate voltage of Q2, providing a controlled charging path that prevents gate voltage fluctuation while maintaining the necessary power control function.
2Reliability
If a conventional semiconductor device adds a negative power source to prevent gate float, then miss-operation can be prevented, but circuit configuration becomes complicated
Solution Approach 1:
The invention merges the function of preventing gate float with the existing driving circuit by using the same low-voltage terminal and control structure. Instead of adding a separate negative power source, the charging transistor Q4 and resistor R1 are integrated into the existing driving circuit framework, sharing the low-voltage terminal and control signals, thereby maintaining reliability while avoiding increased circuit complexity.
Solution Approach 2:
The invention implements self-service by using the existing control signals and voltage levels from the driving circuit to automatically charge the parasitic capacity Cres. The charging transistor Q4 is controlled by the same control terminal that drives the power elements, allowing the circuit to self-regulate and prevent gate float without requiring external negative voltage sources or additional control mechanisms.
3Reliability
If a conventional semiconductor device uses multiple power sources for power element control, then reliable operation can be achieved, but power consumption increases
Solution Approach 1:
The invention makes the existing low-voltage terminal and control circuit serve multiple functions: it controls the main power elements Q1 and Q2, and simultaneously charges the parasitic capacity Cres through the charging transistor Q4. This multi-functionality eliminates the need for separate negative power sources, reducing power consumption while maintaining reliable operation by preventing gate float.
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 miss-operation and simplifies the circuit configuration, reducing power consumption and preventing short-circuits by ensuring the gate voltage of the power elements does not exceed the threshold, even during gate float events.
Implementation Method 1
a current to charge the parasitic capacity Cres between the gate and the collector of the power element Q2 flows, the gate voltage of the power element Q2 rises (gate float)
Data Source
AI summary
A semiconductor device includes first and second power elements and first and second driving circuits. The semiconductor device also includes a resistor having a first end connected to the first power element and a second end connected to the first driving circuit. Furthermore, the semiconductor device includes a switching element connected between the first driving circuit and the first end of the resistor, and turned ON and OFF. When a first input signal is an OFF signal, the first driving circuit causes the first power element to become turned OFF, and when the first input signal is an OFF signal or when a second input signal is an ON signal, the switching element is turned ON.