What’s latch-up

Latch-up is a phenomenon that occurs in integrated circuits (ICs) where a parasitic thyristor-like structure is formed, causing the device to become stuck in a high-current, low-voltage state. This can happen when the voltage at one of the input or output pins of the IC exceeds a certain threshold and triggers the parasitic structure to turn on. Once the latch-up occurs, the device may become permanently damaged or require a power cycle to return to normal operation. Latch-up can be prevented through proper IC design and layout techniques, such as using guard rings and avoiding certain layout configurations.

相关问题

nmos latch up

NMOS的latch-up是指在CMOS晶片中，由于寄生的PNP和NPN双极性BJT相互影响而产生的一种低阻抗通路，导致VDD和GND之间产生大电流。\[2\]为了解决NMOS的latch-up问题，可以采取以下几种解决方案：
1. 添加tap cells：通过在电源轨道上添加tap cells，可以有效地解决latch-up问题。这些tap cells可以是n-well tap或p-substrate tap，根据工艺规则进行排列。\[1\]
2. 使用combained area绘制TAP：在布局设计中，可以使用combained area分层画法来绘制TAP。这种方法将接触和TAP结合在一起，可以更好地满足设计要求。\[1\]
在实际的布局设计中，可以使用工具如Magic或L-edit来绘制TAP。通过合理的布局和设计，可以有效地避免NMOS的latch-up问题。\[1\]
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latch up闩锁效应

Latch-up (闩锁) refers to a type of electrical phenomenon that can occur in integrated circuits (ICs) where a low-impedance path is created between the power supply rails. This can cause the IC to draw excessive current, potentially leading to permanent damage.

The latch-up effect occurs when a parasitic thyristor-like structure within the IC becomes active, which can happen due to a variety of reasons such as overvoltage, overcurrent, or radiation-induced effects. Once triggered, the parasitic structure can latch onto a high-current state, effectively shorting the power supply rails and causing the IC to malfunction.

Designers of ICs take several measures to prevent latch-up, including careful layout, the use of guard rings, and the inclusion of built-in current limiting circuits. However, in certain situations, latch-up may still occur, and it can be a challenging problem to debug and fix.