Zener Diode Reference Voltage Circuit for High Side Driver Stability
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Solution Overview
Problem
Reference voltage circuits in high side driver circuits for power converters face fluctuations due to current flow and displacement currents, leading to potential malfunctions and instability in bipolar transistors, especially when exposed to power supply voltage fluctuations and temperature changes.
Innovation Solution
A reference voltage circuit utilizing a Zener diode with a bias current circuit and a resistance voltage divider network, including low temperature coefficient and high resistance temperature coefficient resistors, generates a stable reference voltage without depletion type MOSFETs or bipolar transistors, using a trimming circuit to regulate resistance values and eliminate temperature dependency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reference voltage circuit using bipolar transistors is used in a high side driver circuit, then overcurrent detection can be performed, but the reference voltage fluctuates due to current flow and displacement current causing bipolar transistor malfunction
Solution Approach 1:
The patent extracts and removes the bipolar transistors from the reference voltage circuit, replacing them with a Zener diode-based circuit. This extraction eliminates the harmful effects of current flow and displacement current that cause bipolar transistor malfunction, while maintaining the overcurrent detection function through the Zener diode's breakdown voltage characteristics.
Solution Approach 2:
The patent replaces expensive and sensitive bipolar transistors with a simpler, more robust Zener diode circuit. The Zener diode circuit is less susceptible to damage from current fluctuations and displacement currents, providing a more reliable reference voltage without requiring complex protection circuits.
2Reliability
If depletion type MOSFET and enhancement type MOSFET are combined to generate reference voltage, then reference voltage can be generated utilizing threshold voltage difference, but manufacturing cost soars
Solution Approach 1:
The patent replaces the expensive depletion type MOSFET with a Zener diode, which is a simpler and cheaper component to manufacture. The Zener diode circuit achieves reference voltage generation through breakdown voltage characteristics rather than threshold voltage differences, eliminating the need for complex MOSFET combinations while reducing manufacturing costs.
Solution Approach 2:
The patent substitutes the MOSFET-based threshold voltage mechanism with a Zener diode-based breakdown voltage mechanism. This substitution simplifies the circuit architecture and reduces manufacturing complexity, as Zener diodes are standard components with well-established fabrication processes.
3Reliability
If reference voltage circuit is incorporated in high side driver circuit, then overcurrent protection can be provided, but reference potential fluctuates due to floating operation and current flow
Solution Approach 1:
The patent extracts the reference voltage generation function from the floating high side driver environment by using a Zener diode circuit that is less sensitive to potential fluctuations. The Zener diode's breakdown voltage provides a stable reference that is not easily affected by the floating operation conditions, maintaining overcurrent protection accuracy.
Solution Approach 2:
The patent changes the operating parameters of the reference voltage circuit by using a Zener diode operated in breakdown region rather than a bipolar transistor in active region. This parameter change makes the reference voltage less sensitive to current flow and potential fluctuations, stabilizing the reference potential during floating operation.
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 provides a cost-effective and stable reference voltage generation, preventing malfunctions and ensuring reliable overcurrent detection, even in high side driver circuits, with minimal manufacturing costs and easy temperature regulation.
Implementation Method 1
a constant current is caused to flow into a Zener diode 11, thereby generating a predetermined breakdown voltage in the Zener diode 11
Implementation Method 2
a resistance voltage divider circuit 16, formed of a first resistor 14 and a second resistor 15 connected in series, connected in parallel with the Zener diode 11 and dividing the breakdown voltage generated in the Zener diode 11, thereby generating a reference voltage
Implementation Method 3
including low temperature coefficient and high resistance temperature coefficient resistors, generates a stable reference voltage without depletion type MOSFETs or bipolar transistors, using a trimming circuit to regulate resistance values and eliminate temperature dependency
Data Source
AI summary
A reference voltage circuit including a constant voltage circuit and a resistance voltage divider circuit. The constant voltage circuit includes a Zener diode, and a bias current circuit connected in series with the Zener diode and causing a constant current to flow into the Zener diode. The resistance voltage divider circuit is connected in parallel with the Zener diode, and includes first and second resistors connected in series. The first resistor is connected to a cathode side of the Zener diode, and is formed of a low temperature coefficient resistor body that is temperature-independent. The second resistor is connected to an anode side of the Zener diode, and is formed of a resistor body having temperature characteristics that are the reverse of output temperature characteristics of the Zener diode.