Level Shift Circuit for dv/dt-Resistant High-Side Signal Transfer
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Solution Overview
Problem
Current level shift circuits in switching power source apparatuses face challenges in preventing malfunctions due to transient voltage dv/dt, especially at higher frequencies, leading to increased power consumption and noise, and are unable to efficiently transmit signals from the low side to the high side without activating protective circuits, which complicates miniaturization and reduces efficiency.
Innovation Solution
A level shift circuit design that includes resistors and n-type MOSFETs with controlled ON/OFF signals, eliminating the need for filter circuits and reducing power consumption by optimizing resistor values and MOSFET currents, allowing for efficient signal transmission and operation at higher frequencies without activating protective circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filter circuits are added to block dv/dt current, then flip-flop malfunction is prevented, but circuit complexity and size increase
Solution Approach 1:
The patent extracts the harmful dv/dt current path by introducing a dedicated discharge path through resistor R2 and diode D2. This separates the harmful transient current from the sensitive flip-flop circuit, allowing the filter circuit to be eliminated while still protecting against malfunction.
Solution Approach 2:
The patent introduces resistor R2 and diode D2 as intermediary elements that provide a controlled discharge path for dv/dt current. These components act as mediators between the switching elements and the flip-flop, allowing harmful transient energy to be dissipated safely without affecting the control circuit.
2Reliability
If filter circuits are added to block dv/dt current, then signal transmission reliability is improved, but power consumption increases
Solution Approach 1:
The patent uses periodic switching of the discharge path through diode D2, which conducts during transient dv/dt events and remains non-conductive during normal operation. This periodic activation of the protective path minimizes continuous power consumption while maintaining reliability during critical transient events.
3Volume of moving object
If switching frequency is increased to miniaturize the apparatus, then size is reduced, but transient voltage dv/dt effects are amplified
Solution Approach 1:
The patent prepares a discharge path in advance through resistor R2 and diode D2 that is ready to activate when transient voltage occurs. This preliminary arrangement of protective components ensures that when high-frequency switching generates dv/dt effects, the discharge path is already in place to immediately handle the transient current, preventing malfunction.
4Reliability
If protective circuits are activated to prevent dv/dt malfunction, then reliability is improved, but signal transmission from low side to high side becomes inefficient
Solution Approach 1:
The patent applies protection locally and selectively - the discharge path through R2 and D2 is activated only when dv/dt transient occurs at specific locations in the circuit. During normal signal transmission, the protective path remains inactive, allowing efficient signal propagation from low side to high side without interference.
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 proposed level shift circuit effectively prevents malfunctions caused by transient voltage dv/dt, reduces power consumption, and enables efficient signal transmission from the low side to the high side, facilitating miniaturization and higher frequency operations while maintaining reliability and efficiency.
Implementation Method 1
a first n-type MOSFET having a drain connected to a second end of the first resistor and a source connected to the ground, a second n-type MOSFET having a drain connected to a second end of the second resistor and a source connected to the ground
Data Source
AI summary
A level shift circuit includes a first resistor connected to a level shift power source, a first transistor having a drain connected to a second end of the first resistor and a source to the ground, a second resistor connected to the level shift power source, a second transistor having a drain connected to a second end of the second resistor and a source to the ground, a pulse generator controlling ON/OFF of the first and second transistors according to an input signal, a control part generating a set signal if the first transistor is ON, a reset signal if the second transistor is ON, and no signal if there is no voltage difference between a voltage at the drain of the first transistor and a voltage at the drain of the second transistor, and a flip-flop providing an output signal according to the set and reset signals.