M
MRW
Hi. I've read some articles about surge input protection; I think it
was regarding switches. Basically, they had a diode's anode connected
to the input terminal and the cathode connected to the voltage source.
It looks like this:
http://bayimg.com/kaebDaaBj
My question is that most diode datasheets that I've seen shows the
minimum forward voltage drop as somewhere around 700mV. Another article
that I read (I think this is about opamps this time), mentioned that
the input is capable of handling a maximum signal amplitude that is VCC
+ 0.3V.
In this situation, does that mean that I would need a diode with a
lower forward voltage drop?
Also, I seem to be confused as to how this type of diode protection
scheme works. Using the picture link, if the signal is higher than the
VCC voltage by an amount greater than the diode forward voltage, then
the diode conducts. So that would mean that the input is now at VCC
voltage levels? If so, then wouldn't the diode "open" up again since
the anode is now at the same voltage level as VCC?
Thanks!
--
was regarding switches. Basically, they had a diode's anode connected
to the input terminal and the cathode connected to the voltage source.
It looks like this:
http://bayimg.com/kaebDaaBj
My question is that most diode datasheets that I've seen shows the
minimum forward voltage drop as somewhere around 700mV. Another article
that I read (I think this is about opamps this time), mentioned that
the input is capable of handling a maximum signal amplitude that is VCC
+ 0.3V.
In this situation, does that mean that I would need a diode with a
lower forward voltage drop?
Also, I seem to be confused as to how this type of diode protection
scheme works. Using the picture link, if the signal is higher than the
VCC voltage by an amount greater than the diode forward voltage, then
the diode conducts. So that would mean that the input is now at VCC
voltage levels? If so, then wouldn't the diode "open" up again since
the anode is now at the same voltage level as VCC?
Thanks!
--