Integrated Circuit Drive Circuit for Power Transistor Safety
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Solution Overview
Problem
Integrated circuits face challenges in safely driving power transistors when high power supply voltages are encountered, leading to increased manufacturing costs due to the need for specialized processes and high-withstand voltage transistors.
Innovation Solution
An integrated circuit configuration that includes a first drive circuit and a second drive circuit to control a power transistor, where the second drive circuit has a lower driving capability than the first, allowing for safe operation of the power transistor even at high power supply voltages, without requiring specialized manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high power supply voltage is used to drive the power transistor, then the driving capability is improved, but the power transistor may be damaged due to exceeding the rated gate voltage
Solution Approach 1:
The patent applies dynamics by making the drive circuit's output impedance variable rather than fixed. The drive circuit dynamically adjusts its output impedance based on the power supply voltage level and the power transistor's operating state. When the power supply voltage is high, the drive circuit increases its output impedance to limit the gate voltage to within the rated range, preventing damage. When the power supply voltage is low, the drive circuit decreases its output impedance to provide sufficient driving capability. This dynamic adjustment resolves the contradiction between driving capability and power transistor safety.
2Reliability
If a high-withstand voltage transistor is used to withstand high power supply voltage, then the reliability is improved, but the manufacturing cost increases due to special manufacturing process
Solution Approach 1:
The patent uses a standard power transistor with normal voltage rating instead of an expensive high-withstand voltage transistor. The drive circuit acts as a protective interface that limits the voltage applied to the gate, allowing the use of cheaper, standard transistors that can be manufactured using conventional processes. This approach trades the cost of a specialized high-voltage transistor for a combination of a standard transistor plus a relatively simple drive circuit, thereby reducing manufacturing costs while maintaining reliability.
3Reliability
If the drive circuit output impedance is increased to limit gate voltage, then the power transistor safety is improved, but the driving capability deteriorates
Solution Approach 1:
The drive circuit dynamically adjusts its output impedance based on operating conditions. When the power supply voltage is high, the drive circuit increases output impedance to limit gate voltage to safe levels. When the power supply voltage is low or during normal operation, the drive circuit decreases output impedance to maximize driving capability. This dynamic behavior allows the system to achieve both voltage protection and sufficient drive strength at different times, resolving the contradiction between safety and performance.
Solution Approach 2:
The patent changes the output impedance parameter of the drive circuit based on the power supply voltage level. By detecting the power supply voltage and adjusting the output impedance accordingly, the system optimizes the trade-off between gate voltage limitation and driving capability. This parameter change allows the drive circuit to adapt to different operating conditions and maintain both safety and performance.
Data Source
AI summary
A power supply circuit includes an inductor, a power transistor configured to control an inductor current flowing through the inductor, and an integrated circuit driving the power transistor. The integrated circuit includes a first terminal that receives a power supply voltage for operating the integrated circuit, generated according to a variation in the inductor current, a second terminal to which a control electrode of the power transistor is coupled, a first drive circuit configured to drive the power transistor via the second terminal during a first time period to turn on the power transistor, and a second drive circuit configured to drive the power transistor via the second terminal during a second time period to turn on the power transistor, the second time period including at least a part of the first time period, driving capability of the second drive circuit being lower than that of the first drive circuit.