what is feature of this diode in the buffer

[dinosaur078]

dear every body
i see there some diodes in the buffer blocks , but i do not know , they are for what ? why should use it in the circuit
thank you in advance

 

[btbass]

They limit negative voltages on the input pins which could damage the device.

 

[dinosaur078]

thank btbass
could you please explain in detail , why it can protect the device out of the damage of negative voltage

 

[btbass]

You have not shown much of the circuit?
But for ESD protection, inputs normally have a series resistor to limit the current and diodes to limit the voltage excusions on the pin.
A negative spike on the input will be limited to ~0.6V, the diode drop, and so prevent the negative spike appearing on the input pin and maybe damaging the device.

 

[emresel]

Zener dioodes may be used for some applications, to prevent both positive abd negative spikes damaging to cct.

 

[kishanreddy]

for ESD protection one can use schottky diodes or zener diodes the prob y these only mean they must respond very speed so (schottky) have less forwrd and reverse recovery transition and also it must hv low frwd drop, the only n main thing is they must hv to respond very quickly to bypass the sudden spikes