Switching Converter Control Circuit for Zero Current Protection
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Solution Overview
Problem
Designing control circuits for switching converters with zero current protection is challenging due to difficulties in setting appropriate current thresholds, which can lead to false triggering or no-triggering issues under light load conditions, affecting efficiency.
Innovation Solution
A control circuit and method for a switching converter that includes ON and OFF signal generating circuits, comparators, and a logic circuit to manage the high and low side switches based on predefined thresholds and timing, ensuring the high side switch remains on until the current exceeds a threshold and the low side switch is turned off when the current falls below a specific threshold, avoiding false triggering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the high side switch is turned off immediately when preset time ends, then the control structure is simple, but the switch may turn off before current reaches threshold under light load
Solution Approach 1:
The patent applies preliminary action by extending the high side switch on-state beyond the preset time when the current threshold has not been reached. The control circuit monitors the current threshold condition and keeps the switch on until both the preset time expires and the threshold is met, preventing premature switch-off under light load conditions.
Solution Approach 2:
The system uses feedback by continuously monitoring whether the current threshold has been reached and adjusting the high side switch timing accordingly. The control circuit receives feedback about the current status and modifies the switch-off timing to ensure accurate threshold achievement, resolving the timing accuracy issue.
Data Source
AI summary
A control circuit for switching converter has an ON signal generating circuit, an OFF signal generating circuit, a first comparator, a second comparator and a logic circuit. The switching converter has a high switch and a low side switch connected in series. The ON signal generating circuit provides an ON signal based on a reference signal and a feedback signal. The OFF signal generating circuit provides an OFF signal. The first comparator provides a first comparing signal based on a comparing result between a first threshold and a current through the high side switch. The second comparator provides a second comparing signal based on a comparing result between a second threshold and a current through the low side switch. The logic circuit provides a first switching signal to control the high side switch ON and OFF and a second switching signal to control the low side switch ON and OFF.