Why schould a Schottky diode be connected in parallel to resistor?
In some over voltage (or spikes) protections, a Schottky diode is used, which is connected in parallel to a resistor.
I can not understand the role of the resistor.
In some over voltage (or spikes) protections, a Schottky diode is used, which is connected in parallel to a resistor.
I can not understand the role of the resistor.
Thanks for your reply.
In the attachment is an example of a driver with two schottky diodes for an over voltage protection.
I understand, how the schottky diodes work but I can not understand, why should resistors be connected to these diodes.
Re: Why schould a Schottky diode be connected in parallel to resistor?
Thanks for your answer.
Because of parasitic effects, the spikes appear on Vout.
The Schottky diodes prevents the negative [spikes < (0 V-VD of Schottky] and positive spikes [spikes > (VDD+ VD of Schottky].
But which role has resistors??
Re: Why schould a Schottky diode be connected in parallel to resistor?
Given that the resistors are the same value, a practical use would be for trying to match a characteristic impedance. If they were different values, I'd suggest it would be for the output
to be at a specific DC bias when the driver is not being driven (tri-stated). The diodes could in most cases accomplish the midpoint-level bias point by themselves, depending on current requirements.
It's also functionality. If you're trying to limit a voltage across a resistor, you'd put a diode across it. The op asked 'why put a resistor across a diode'. It's the same difference as putting a house under a roof.