Switching Regulator 100% Duty Detection Light Load
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Solution Overview
Problem
Existing switching regulators face issues where the output voltage exceeds safe levels when the load becomes a light load, leading to potential damage due to excessive voltage as the PMOS transistor remains on, disrupting the feedback function.
Innovation Solution
A switching regulator is designed with an on-time control circuit, flip-flop circuit, output control circuit, and 100% DUTY detection circuit to prevent the high-side switching element from remaining on during light loads, ensuring the output voltage does not exceed desired levels by incorporating a 100% DUTY detection mechanism to turn off the PMOS transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If COT control is used to maintain output voltage, then output voltage regulation is improved, but under light load conditions the PMOS transistor remains continuously on causing excessive output voltage
Solution Approach 1:
The 100% DUTY detection circuit proactively monitors the duty cycle before excessive voltage occurs. When the duty cycle reaches 100%, the circuit generates a reset signal to the flip-flop circuit, forcing the PMOS transistor to turn off before dangerous voltage levels can develop. This preliminary detection and intervention prevents the harmful condition rather than reacting to it after occurrence.
2Stability of the object's composition
If the PMOS transistor remains on during light load, then output voltage is maintained, but the feedback function fails and excessive voltage damages the load
Solution Approach 1:
The system employs dual feedback mechanisms: the original feedback circuit monitoring output voltage through the error comparator, and the 100% DUTY detection circuit providing a secondary feedback path that specifically monitors duty cycle. When the duty cycle reaches 100%, this secondary feedback overrides the normal voltage feedback by resetting the flip-flop, ensuring the PMOS transistor turns off to prevent harmful excessive voltage conditions.
Data Source
AI summary
To provide a COT-controlled switching regulator capable of preventing an output voltage from excessively exceeding a desired voltage even though a light load is connected to an output terminal. A switching regulator of the present invention is configured to be equipped with a 100% DUTY detection circuit which detects a 100% DUTY at which a high-side switching element continues an on state for a prescribed time or more and outputs a detected signal to an output control circuit and to cause the output control circuit to turn off the high-side switching element when the output control circuit receives the detected signal therein.