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How does a Zener diode protect an overvoltage circuit?
The pinout for a FMMT718 is given in a tabular form below. This is one of the two configurations of overvoltage protection circuits using Zener diode. This circuit not only protects the load side circuit but also regulates the input supply voltage to maintain a steady voltage.
Do you need a Zener diode for GPIO?
If you are planning on using some of these circuits, it is recommended you research similar circuits to determine the best configuration for your needs. This method uses a 3.3V Zener diode to limit the voltage which will be applied to the GPIO pins.
What should the Zener voltage be for PSpice?
For the above example in Pspice, the Zener voltage is 6.8V. There will be some situations where the targeted Zener diode voltage is not available. In such cases, a close value of the Zener diode can be chosen. For example, for overvoltage protection up to 7V, a 6.8V Zener diode is a close value.
What is the threshold value for a Zener diode?
The design of the circuit is such that the pre-set value of the circuit is the rating of the Zener diode. So the threshold value over which the circuit does not conduct is approximately 5.1V. The conduction of the transistor Q1 is dependent on the base emitter voltage of the transistor.
How can I protect my circuit from overvoltage?
A power supply can fail in many ways; similarly, there can be many ways to protect a circuit from overvoltage. The simplest way is to connect a fuse at the input supply side. But, the disadvantage of using a fuse is that it is one-time protection, because as the voltage exceeds the pre-set value, the fuse wire burns up, causing the circuit to open.
What happens to output voltage of overvoltage circuit?
When the circuit’s output voltage starts to raise, this increases the Vbe of the transistor and it conducts less. This in turn reduces the output voltage, keeping the output voltage almost constant. The circuit diagram for the Overvoltage protection circuit is given below.
How does a 10A PTC fuse protect a Zener?
The 10A PTC fuse (or any fuse) will current protect my voltage regulator and downstream parts but the 10A fuse won’t blow fast enough to save the Zener and if the zener fails I lose my voltage protection. – Ahh! How do I overvoltage protect a 10A, 30v DC signal?
Can a Zener fuse blow at 12 volts?
Go for a 15 volt zener is my advice then there is never any possibility of it blowing the fuse at 12 volts. The current through the zener will be determined by the source impedance of your 12/24 volt supply and the associated wiring. Most supplies will have a low enough internal impedance that the zener diode will fail when it conducts.