Switching Converter Ring Control for High-Side Turn-Off Spikes
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Solution Overview
Problem
Switching converters experience transient voltage spikes during the turn-off of high-side transistors, which can damage circuit components due to parasitic inductance and capacitance, particularly affecting the driver circuit.
Innovation Solution
A ring control circuit is introduced to detect and mitigate these transients by discharging parasitic capacitors and controlling the turn-off process of high-side transistors, reducing the amplitude of voltage spikes through a combination of transistors, resistors, and logic gates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the high-side transistor is turned off quickly to improve switching speed and efficiency, then productivity is improved, but transient voltage spikes are generated that can damage circuit components
Solution Approach 1:
The ring control circuit is activated before the high-side transistor is turned off to prepare the discharge path for parasitic capacitors. The circuit detects the turn-off event and preemptively discharges the capacitors through the low-side transistor, preventing voltage spikes before they can occur.
Solution Approach 2:
The ring control circuit acts as an intermediary between the driver circuit and the power switch. It monitors the switching process and controls the low-side transistor to discharge parasitic capacitors, mediating the turn-off process to eliminate harmful voltage spikes while maintaining fast switching.
2Reliability
If parasitic capacitors are discharged during transistor turn-off to reduce voltage spikes, then reliability is improved, but additional control circuitry is required increasing device complexity
Solution Approach 1:
The ring control circuit performs multiple functions: it detects the turn-off event, controls the discharge of parasitic capacitors, and protects the driver circuit. By consolidating these functions into a single control structure, the patent reduces overall complexity while achieving reliable protection.
Solution Approach 2:
The ring control circuit automatically detects and responds to turn-off events without external intervention. The circuit self-regulates the discharge process by monitoring voltage conditions and controlling the low-side transistor, eliminating the need for complex external control mechanisms.
3Object-affected harmful factors
If the turn-off process is slowed to reduce transient voltages, then harmful factors are reduced, but switching efficiency and productivity decrease
Solution Approach 1:
The discharge of parasitic capacitors is performed periodically at each turn-off event rather than continuously. The ring control circuit activates the discharge path only when needed (during turn-off), maintaining fast switching during normal operation while protecting against transients during switching events.
Solution Approach 2:
The discharge path is prepared in advance before the voltage spike can occur. By pre-configuring the discharge path through the low-side transistor and parasitic resistors, the circuit can quickly dissipate energy without slowing the overall switching process, maintaining efficiency while reducing harmful transients.
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 ring control circuit effectively reduces transient voltages across critical circuit nodes, protecting components from damage and ensuring stable operation by slowing the turn-off process of high-side transistors.
Implementation Method 1
A ring control circuit is introduced to detect and mitigate these transients by discharging parasitic capacitors
Data Source
AI summary
A circuit includes circuit input and output, first, second and third transistors, a driver circuit, a control circuit, a logic gate, and a capacitor. The driver circuit has a PWM input, and an output coupled to a control terminal of the first transistor. The control circuit has a PWM output coupled to the PWM input, and an enable output. The logic gate has a first input coupled to the circuit input, a second input coupled to the enable output, and a gate output. The second transistor has a first terminal, a second terminal coupled to the circuit output, and a control terminal coupled to the gate output. The third transistor is coupled between the circuit input and the circuit output, and has a control terminal coupled to the first terminal of the second transistor. The capacitor is coupled between the circuit input and the control terminal of the third transistor.