What is Latchup? and when it will get triggered..?

[kish12334]

Hi Everyone,

I want to know what is cmos latchup when and how will get trigger..?
Can any one help me...?

Regards
Kishore

 

[mpig09]

Hi kish12334:

Simple Description:
If the parasitic BJT is turned on, the VDD will be latch at veb (~0.7V) .

The detail can be found in google.

How to trigger:
I met the trigger condition is:
1. layout is not good
2. fast power on the chip

I hope it will help you.
mpis

 

[kish12334]

thank u mpis

 

[schmitt trigger]

Sometimes, a fast transient on any of the I/O lines (for instance, from ESD) will trigger it.

A device which has suffered that fate will remain latched up until power is turned off. Therefore....If left unattended for extended periods of time, the device can self destruct.

 

[crutschow]

A significant substrate current can trigger latchup, such as an overvoltage (above the power supply voltage) or undervoltage (voltage below ground) on one of the inputs.