Semiconductor Device Dynamic Gate Voltage Clamp for Short Circuit Protection
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Solution Overview
Problem
Conventional semiconductor devices face challenges in efficiently determining short circuits during power switching operations, particularly when the saturation current is at a minimum, leading to increased short circuit energy and potential restrictions on chip miniaturization due to high drain-source or collector-emitter voltages.
Innovation Solution
A semiconductor device with an output current detector, voltage detector, and clamp circuit that adjusts the gate voltage based on detected voltages to ensure the output current exceeds the threshold current required for short circuit detection, minimizing short circuit energy by dynamically controlling the clamp voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If gate voltage is clamped at a predetermined value during short circuit determination, then output current is limited and energy consumption is reduced, but output current may not exceed threshold current when saturation current is at minimum
Solution Approach 1:
The clamp voltage is dynamically adjusted based on the detected voltage across the power switching device. When saturation current is at minimum, the clamp voltage is increased to ensure output current exceeds the threshold for reliable short circuit detection. When voltage across the device is high, the clamp voltage is reduced to limit energy consumption. This dynamic adjustment resolves the contradiction between reliable detection and energy efficiency.
Solution Approach 2:
The clamp voltage parameter is changed based on operating conditions (detected voltage levels). The control unit adjusts the clamp voltage to different predetermined values depending on whether the power switching device is in a state with minimum saturation current or high drain-source/collector-emitter voltage, optimizing both detection reliability and energy consumption for each operating state.
2Reliability
If gate voltage is not clamped, then output current can exceed threshold current for reliable short circuit detection, but energy consumption during short circuit increases
Solution Approach 1:
Instead of using a fixed clamp voltage or no clamping, the system dynamically adjusts the clamp voltage based on real-time detection of the voltage across the power switching device. This ensures the minimum necessary current for detection while minimizing excess current that would increase energy consumption.
Solution Approach 2:
The control unit uses feedback from the voltage detector to adjust the clamp voltage. The detected voltage information feeds back to the control unit, which then adjusts the clamp circuit to set an appropriate clamp voltage that balances detection reliability with energy consumption control.
3Power
If high drain-source or collector-emitter voltage is present, then power switching capability is maintained, but short circuit energy increases and chip miniaturization is restricted
Solution Approach 1:
The clamp circuit is activated in advance during the short circuit determination phase to prevent excessive current flow before it can cause significant energy loss or damage. By clamping the gate voltage at an appropriate level based on detected conditions, the system prepares for and prevents energy loss during potential short circuits.
Solution Approach 2:
The system quickly determines whether a short circuit exists by monitoring output current against threshold, and if a short circuit is detected, the clamp circuit immediately limits further current flow. This rapid detection and response minimizes the duration of high energy states, reducing overall short circuit energy loss.
Data Source
AI summary
A semiconductor device turns on and off a power switching device having a gate terminal and output terminals between which an output current is produced by a gate voltage applied to the gate terminal. The semiconductor device includes: an output current detector detecting a current value correlated with the output current; a voltage detector detecting a voltage across the output terminals of the power switching device; a clamp circuit clamping the gate voltage at a predetermined value; and a controller controlling the clamp circuit to adjust the gate voltage based on the voltage detected by the voltage detector. The controller controls the clamp circuit to set the gate voltage to be at a minimum voltage according to the detected voltage to cause the output current to be larger than a threshold current required for detecting the short circuit in the power switching device.