Integrated Transistor Clamping Circuit for Voltage Spike Protection
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Solution Overview
Problem
Power transistor devices are vulnerable to voltage spikes during transitions between operating states, which can exceed their voltage blocking capability, leading to potential damage or degradation, and designing for higher blocking capability increases conduction losses and costs.
Innovation Solution
An electronic circuit with a first transistor device and a clamping circuit, where a second transistor device with a parallel load path is integrated in the same semiconductor die, and a drive circuit controls the second transistor device based on resistor voltage to protect the first transistor device from voltage spikes by clamping the load path voltage below its threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage blocking capability of the transistor device is increased to withstand voltage spikes, then the transistor device can protect itself from damage, but conduction losses and price increase
Solution Approach 1:
A clamping circuit with a second transistor device is introduced as an intermediary protective element. This second transistor device is controlled by a drive circuit to activate during voltage spikes and clamp the voltage to a safe level, protecting the first transistor device without requiring it to have high voltage blocking capability. The clamping circuit acts as a mediator that handles the voltage spike protection function separately from the main power switching function.
Solution Approach 2:
The protection function is segmented from the main power transistor device and implemented as a separate clamping circuit with a second transistor device. This segmentation allows the first transistor device to be optimized for low conduction losses with lower voltage blocking capability, while the second transistor device handles the voltage spike protection independently through controlled activation.
2Reliability
If the voltage blocking capability of the transistor device is increased to withstand voltage spikes, then the transistor device can protect itself from damage, but the price increases
Solution Approach 1:
The clamping circuit with the second transistor device serves as an intermediary protection mechanism that is activated only during voltage spike events. This allows the first transistor device to be manufactured with lower voltage blocking capability and thus lower cost, while the second transistor device provides the necessary protection during abnormal conditions.
Solution Approach 2:
The second transistor device is dynamically controlled through the drive circuit to activate only when voltage spikes occur during transitions between operating states. This dynamic activation allows the system to use a lower-cost first transistor device for normal operation while providing protection only when needed, optimizing the overall cost structure.
3Speed
If the transistor device switches faster from on-state to off-state, then the switching performance improves, but voltage spikes increase due to parasitic effects
Solution Approach 1:
The drive circuit is configured to anticipate voltage spikes during the transition from on-state to off-state and activates the second transistor device in advance or simultaneously with the voltage spike occurrence. This preliminary anti-action clamps the voltage before it can reach damaging levels, allowing the first transistor device to switch faster without suffering from voltage spike damage.
Solution Approach 2:
The second transistor device and clamping circuit act as an intermediary that absorbs and limits voltage spikes during fast switching transitions. This allows the first transistor device to operate at high switching speeds with improved performance while the clamping circuit handles the harmful voltage spike effects independently.
Data Source
AI summary
An electronic circuit and a method are disclosed. The electronic circuit includes: a first transistor device having a load path between a first load path node and a second load path node; and a clamping circuit connected to the load path of the first transistor device. The clamping circuit includes: a second transistor device having a load path connected in parallel with the load path of the first transistor device, and a control node; and a drive circuit configured to drive the second transistor device. The drive circuit includes a clamping element and a resistor connected in series between the first and second load path nodes of the first transistor device. The drive circuit is configured to drive the second transistor device dependent on a voltage across the resistor. The first transistor device and the clamping circuit are integrated in a same semiconductor die.