Switch Pair Controller Using Dead Time to Block Cross-Conduction
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Solution Overview
Problem
Existing electronic circuits, particularly synchronous switching converters, face the issue of cross-conduction where both switches connected in series between a power supply and ground are turned on simultaneously, creating an unwanted path and risking damage to the components.
Innovation Solution
A controller is introduced with a first and second driving circuit, an event detector circuit, a pulse generator circuit, and a combinatorial sampling circuit to generate control signals that prevent cross-conduction by ensuring one switch is off when the other is on, using a dead time signal and truth table to update control signals based on detected edges in logic electrical signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If both switches are controlled to be on simultaneously to improve circuit functionality, then the circuit can operate in both buck and boost modes, but cross-conduction occurs creating an unwanted path between power supply and ground
Solution Approach 1:
The controller predicts future states of the switching converter by analyzing current states and transition rules, determining which switch should be turned on before the actual switching event occurs. This predictive approach ensures that only one switch is activated at any given time, preventing cross-conduction while enabling seamless transitions between buck and boost modes.
Solution Approach 2:
The controller continuously monitors the current operating state of the switching converter and uses this feedback to determine the next appropriate state. By implementing state-machine logic that tracks the current mode and predicts future states, the controller ensures proper sequencing of switch operations, preventing simultaneous activation of both switches while maintaining adaptability between different conversion modes.
2Reliability
If complex control logic is implemented to prevent cross-conduction, then cross-conduction is avoided, but the device complexity increases
Solution Approach 1:
The control logic is segmented into distinct state definitions and transition rules, where each state represents a specific operating condition (buck mode, boost mode, mode transition). This segmentation simplifies the overall control structure by breaking down the complex switching behavior into manageable, predictable state transitions, reducing the complexity of the controller while ensuring reliable prevention of cross-conduction.
Solution Approach 2:
The controller uses its own internal state machine to automatically manage the switching sequences, eliminating the need for external control signals or additional sensing circuits. The state-machine logic self-regulates the switch operations based on predefined transition rules, reducing the overall system complexity while maintaining high reliability in preventing cross-conduction events.
Data Source
AI summary
A controller for an electronic circuit that includes a first and a second switch is provided. The controller includes an event detector stage that receives logic electrical signals and a pulse generator circuit, which is coupled to the event detector stage and generates a dead time signal based on edges of the logic electrical signals detected by the event detector stage. The dead time signal includes pulses delimited by an edge of a first type and by a subsequent edge of a second type. A combinatorial sampling circuit generates a first and a second sampled preliminary signal. An update stage updates the values of the first and the second control signals at each pulse of the dead time signal based on the first and the second sampled preliminary signals, subsequently to the edge of the first type or the second type of the pulse of the dead time signal.