Switching Regulator Protection for Residual Inductor Current
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Solution Overview
Problem
Existing switching regulators and power management integrated circuits (PMICs) face issues with stability during power-off conditions, particularly due to overheating and damage from residual currents during overcurrent or overvoltage events, which can lead to thermal shutdown and component failure.
Innovation Solution
The switching regulator includes a switching controller that detects the direction of inductor current during protective events, stops the switching operation, discharges residual current, and fully turns off the transistors, while the PMIC monitors input and output voltages and temperatures to manage these events, ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching regulator continues operation during overcurrent or overvoltage events, then power conversion function is maintained, but residual currents cause overheating and component damage
Solution Approach 1:
The switching controller detects protective operation events (overcurrent, overvoltage, thermal conditions) and preemptively stops switching operations and discharges residual currents before they can cause overheating or component damage. This preliminary protective action prevents the harmful effects of residual currents while maintaining the ability to resume normal operation after the protective event clears.
2Reliability
If the switching regulator stops operation to discharge residual current, then component damage is prevented, but power conversion function is interrupted
Solution Approach 1:
The switching controller performs preliminary discharge of residual currents by fully turning on the P-type or N-type transistor depending on current direction, before the thermal damage can occur. This preliminary discharge action quickly eliminates the harmful residual current, allowing the regulator to resume normal operation faster and with less interruption time.
Solution Approach 2:
The switching controller continuously monitors protective operation events and uses feedback signals to determine when to stop switching operations and when to resume them. The controller detects the direction of inductor current and adjusts transistor gating accordingly, providing closed-loop control that minimizes operation interruption while ensuring thermal safety.
3Reliability
If the switching controller fully turns off transistors during protective events, then residual current discharge is achieved, but switching response time increases
Solution Approach 1:
The switching controller dynamically adjusts transistor gating based on real-time detection of protective operation events and inductor current direction. Rather than using fixed off-states, the controller selectively fully turns on or off specific transistors (P-type or N-type) depending on the direction of residual current, enabling faster and more targeted discharge paths that maintain switching response speed while ensuring effective protective operation.
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
A switching regulator (100) is provided. The switching regulator (100) comprises a switching controller (201) configured to activate a switching conversion operation based on an enable signal, a gate driver (201) configured to generate first and second gate signals (PD, ND) under control of the switching controller (210) and a switching circuit (301) configured to convert an input voltage (VDD) applied to an input voltage node (N1) to a output voltage (VO). The switching circuit (301) includes a P-type transistor (111) connected between the input voltage node (N1) and a switching node (Nsw) and gated based on the first gate signal (PD), an N-type transistor (112) connected between the switching node (Nsw) and a power ground terminal and gated based on the second gate signal (ND) and an inductor (L) connected between the switching node (Nsw) and an output node (No) and configured to output the output voltage (VO).