Power Supply Circuit Short-Circuit Detection After Soft Start
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Solution Overview
Problem
Power supply circuits often lack effective short circuit protection after the completion of a soft start, leading to potential damage when a short circuit occurs.
Innovation Solution
A power supply circuit is configured to detect a short circuit on a power supply node and trigger an automatic fault protection (AFP) mode after completion of a soft start, using a logic circuit to monitor the voltage and trigger AFP when it falls below a threshold, thereby preventing damage to transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If short circuit protection is implemented after soft start completion, then transistor damage is prevented, but current consumption increases
Solution Approach 1:
The patent implements preliminary short circuit detection by monitoring the power supply node voltage before full operation begins. The logic circuit is configured to detect short circuits only after soft start completion, allowing the system to prepare protection mechanisms in advance without continuously consuming high current during normal operation.
Solution Approach 2:
The power supply circuit performs self-diagnosis through the logic circuit that automatically monitors the power supply node voltage and triggers AFP mode when a short circuit is detected. The system serves itself by detecting faults and activating protection without external intervention, minimizing the need for additional protection circuitry that would increase current consumption.
2Reliability
If continuous monitoring is implemented to detect short circuits, then detection reliability improves, but power consumption increases
Solution Approach 1:
The patent implements periodic monitoring by enabling the logic circuit to detect short circuits only after soft start completion. This periodic activation rather than continuous monitoring reduces power consumption while maintaining detection reliability during the critical post-soft-start period when short circuits are most likely to occur.
Solution Approach 2:
The monitoring system changes its operational parameters based on the system state. During soft start, monitoring is disabled to minimize power consumption. After soft start completion, the logic circuit activates detection by monitoring the power supply node voltage, changing the system's monitoring parameter from inactive to active only when needed.
3Reliability
If automatic fault protection mode is triggered immediately, then circuit safety is improved, but false triggering during soft start increases
Solution Approach 1:
The patent uses preliminary soft start to stabilize the power supply node voltage before enabling short circuit detection. This preliminary action ensures that the voltage has settled to its normal operating level, providing a stable baseline for accurate short circuit detection and preventing false triggers during the transient soft start period.
Solution Approach 2:
The patent applies preliminary anti-action by disabling short circuit detection during soft start and only enabling it after soft start completion. This prevents the detection mechanism from reacting to normal voltage fluctuations during soft start, thereby avoiding false positive triggers while maintaining circuit safety.
Data Source
AI summary
Certain aspects of the present disclosure provide techniques and apparatus for supplying power, including short circuit protection. One example power supply circuit generally includes a switching regulator including an output coupled to a first power supply node, a battery node for coupling to a battery, a switch coupled between the first power supply node and the battery node, a first transistor including a gate coupled to the first power supply node and a source coupled to a reference potential node of the power supply circuit, and a first current source or a resistive element, coupled between a power supply rail and a drain of the first transistor. The power supply circuit may be configured to detect a short circuit on the first power supply node and trigger an automatic fault protection (AFP) mode after completion of a soft start of a voltage on the first power supply node.