Gated Over-Voltage Comparator Circuit for Switching Regulator Overshoot Reduction
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Solution Overview
Problem
Switching regulators operating in Burst Mode experience excessive output voltage overshoot due to slow system loop response time, leading to instability and inefficiency in power management, particularly when transitioning between SLEEP and WAKE states.
Innovation Solution
Incorporating a gated over-voltage comparator circuit with a one-shot timer that selectively enables or disables the sensing circuitry responsible for burst WAKE regulation, deactivating it only during a limited period after the regulator enters the WAKE state to prevent overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the regulator operates in Burst Mode to reduce power consumption, then power efficiency is improved, but output voltage stability deteriorates due to excessive overshoot
Solution Approach 1:
The one-shot timer activates the over-voltage comparator before the WAKE state completes, preparing the protection mechanism in advance to detect and correct voltage overshoot as soon as it occurs during the transition to WAKE state
Solution Approach 2:
The over-voltage comparator continuously monitors the output voltage during the WAKE state and provides feedback to the control circuit, which adjusts the PWM duty cycle or triggers shutdown to correct excessive voltage and maintain stability
2Measurement precision
If the over-voltage comparator is continuously active to prevent overshoot, then output voltage control precision is improved, but power consumption increases
Solution Approach 1:
The over-voltage comparator operates periodically rather than continuously, being activated only during the WAKE state when the regulator is actively supplying power and voltage overshoot is most likely to occur, thereby maintaining precision when needed while minimizing power consumption during SLEEP state
Solution Approach 2:
The one-shot timer pre-activates the over-voltage comparator at the beginning of the WAKE state, ensuring precise monitoring is ready before voltage overshoot can occur, and automatically deactivates it after a predetermined time period to conserve power
3Speed
If the regulator responds quickly to load changes, then response speed is improved, but output voltage overshoot increases
Solution Approach 1:
The over-voltage comparator provides real-time feedback on output voltage levels during the WAKE state, allowing the control circuit to detect overshoot conditions and immediately adjust the switching regulator's operation to correct the voltage, thus maintaining precision despite fast response
Solution Approach 2:
The system applies preliminary protective action by activating the over-voltage comparator before excessive overshoot can develop, and the comparator's threshold is set to trigger correction before the overshoot becomes problematic, effectively preventing the harmful effect while maintaining fast response
Data Source
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AI summary
Switching regulator Burst Mode control circuitry is provided for limiting voltage overshoot at the output of a switching regulator operating in power saving Burst Mode. The Burst Mode control circuitry may include regulator load current sensing circuitry which may be operative to put and maintain the regulator in the SLEEP state when the load current amplitude is below a threshold. The control circuitry may also include gated over-voltage comparator circuitry operative to reduce regulator output overshoot and to eliminate erroneous deactivation of the regulator switch circuitry when the regulator is not operating in Burst Mode. The gated over-voltage circuitry may include a one-shot timer circuit.