LIGBT Clamp Diode Prevents PNPN Latch-Up
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Solution Overview
Problem
Conventional power devices with lateral insulated gate bipolar transistors (LIGBTs) face challenges in preventing the unwanted PNPN latch-up effect during short circuit tests, particularly due to excessive gate-emitter voltage coupling, which can lead to damage.
Innovation Solution
Incorporating a clamp diode, such as a Zener diode, electrically connected to the gate and drain of the LIGBT to limit the gate voltage to a predetermined threshold, preventing excessive voltage surges and thus reducing the likelihood of latch-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the gate voltage is allowed to rise during short circuit tests, then the LIGBT can handle higher current, but excessive gate-emitter voltage coupling causes PNPN latch-up effect and device damage
Solution Approach 1:
A clamp diode is introduced as an intermediary component connected between the gate and drain of the LIGBT. This clamp diode acts as a mediator that limits the gate-emitter voltage to a predetermined threshold level, preventing excessive voltage coupling that would trigger the parasitic PNPN latch-up effect while allowing the device to operate at high currents during short circuit conditions.
2Reliability
If the gate voltage is clamped to prevent latch-up, then device reliability improves, but the ability to handle high current during short circuit tests is reduced
Solution Approach 1:
The clamp diode is configured with specific electrical parameters (breakdown voltage, forward voltage drop) that are optimized to maintain device reliability while preserving current handling capability. By carefully selecting the clamp voltage threshold and diode characteristics, the system allows high current flow during short circuit tests while preventing the gate-emitter voltage from reaching levels that would trigger latch-up.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The clamp diode effectively prevents drastic increases in base and conduction currents, thereby avoiding the PNPN latch-up effect and protecting the power device from damage during short circuit tests.
Implementation Method 1
a clamp diode having a clamp forward terminal and a clamp reverse terminal, which are electrically connected to a drain and a gate of the LIGBT, respectively, to clamp a gate voltage applied to the gate not to be higher than a predetermined voltage threshold
Data Source
AI summary
A power device which is formed on a semiconductor substrate includes: a lateral insulated gate bipolar transistor (LIGBT), a PN diode and a clamp diode. The PN diode is connected in parallel to the LIGBT. The clamp diode has a clamp forward terminal and a clamp reverse terminal, which are electrically connected to a drain and a gate of the LIGBT, to clamp a gate voltage applied to the gate not to be higher than a predetermined voltage threshold.