How could ESD cause latchup?
ESD = electrostatic discharge
I am reading my textbook, and understand this does happen, but how exactly?
- mark pLv 51 decade agoFavorite Answer
The other answers discussed damage to a chip through ESD. Latchup is a slightly different phenomenon. Latchup usually happens when you take an input (or output) of an IC, and put a voltage either higher than VCC or lower than Ground on it.
When this happens, because of the way IC's are made, there are all kinds of unintentional paths that current can flow in (and basically, a whole bunch of transistors and diodes appear in the circuit that don't have any effect when the circuit is operating normally. This can cause an output to get "stuck" in one particular state, or for an input to go dead.
Latchup isn't always fatal to a chip; sometimes it will fix itself if you turn the power off and then back on again. (In other cases, it can do permanent damage and destroy the chip).
ESD (even if it's far away from the circuit itself, such as zapping the case of an instrument) can cause circuit voltages to spike (either positive or negative) driving the signals beyond their legal ranges and triggering latchup.
- 1 decade ago
A spark is triggered when the electric field strength exceeds approximately 10 – 30 kV/cm (the dielectric field strength of air). This may cause a very rapid increase in the number of free electrons and ions in the air, temporarily causing the air to abruptly become an electrical conductor in a process called dielectric breakdown.
esd often occurs with very high voltages, even tho the current is miniscule in the chips containing millions and billions tiny transistors, there is a possibility that few of them migth get damaged, the device will not usually become dead broken but will have errors in functioning. like dead bits in memory or cpu making calculation errors sometimes. these kinds of faults migth not be noticable at first but will cause unexplaineable errors in the long run
- billrussell42Lv 71 decade ago
A spark generated by static electricity (which is thousands of volts) discharged into an IC or a circuit can cause transistors to be severely damaged, ie, shorted.
The transistors in an IC can't handle more than about 10 volts before junctions get punctured and shorted.