Semiconductor Switch Startup Control for Surge Current Limiting
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Solution Overview
Problem
Existing semiconductor devices face challenges in managing surge currents and overcurrents during startup, leading to potential heat concentration and reduced operational safety, while also requiring high overcurrent detection values that may not accurately detect abnormal currents.
Innovation Solution
The semiconductor device incorporates a control circuit that manages transistor states to inhibit surge currents and reduce the number of transistors turned off during startup, utilizing an active clamp circuit to limit inter-terminal voltage and an overcurrent detection circuit to detect stable currents, with optional counters or external signals to further optimize transistor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If transistors are turned off during startup to manage current, then surge currents are inhibited, but startup time increases and operational reliability decreases
Solution Approach 1:
The patent applies dynamics by making the transistor switching state time-dependent rather than static. The control circuit dynamically adjusts transistor switching based on elapsed time since power supply activation, transitioning from a first switching state (some transistors off) during initial startup to a second switching state (all transistors on) after a predetermined period. This dynamic approach allows surge current protection during critical startup while ensuring full operational capability is restored, resolving the contradiction between surge inhibition and operational reliability.
2Reliability
If high overcurrent detection values are used to detect abnormal currents, then false detection is reduced, but surge currents and overcurrents during startup cannot be accurately detected
Solution Approach 1:
The patent applies dynamics by making the overcurrent detection threshold time-dependent. The control circuit uses a time-dependent detection value that varies based on elapsed time since power supply activation. During initial startup (first predetermined period), a lower detection threshold is used to accurately detect surge currents. After the predetermined period elapses, the detection threshold increases to prevent false detection during normal operation. This dynamic threshold adjustment resolves the contradiction between detection reliability and measurement precision.
3Reliability
If all transistors are kept on during startup, then operational reliability is maintained, but surge currents and heat concentration occur
Solution Approach 1:
The patent applies preliminary action by proactively turning off specific transistors during the initial startup period before full operational load is applied. The control circuit identifies and switches off transistors that would otherwise conduct surge currents during power supply activation. This preliminary protective action prevents heat concentration and surge currents before they can cause damage, while the control circuit ensures that after the predetermined period, all transistors are turned on to maintain full operational reliability.
Data Source
AI summary
The present disclosure provides a semiconductor device. The semiconductor device includes: a first terminal; a second terminal; and at least one first switch element and at least one second switch element, configured to be connected between the first terminal and the second terminal; an overcurrent detection circuit, configured to detect an overcurrent flowing through the first terminal; and an off circuit, configured to turn off at least a portion of the at least one second switch element when the semiconductor device is started.