Understanding Peak Inverse Voltage (PIV): Why Is It Important?

In summary, the Peak Inverse Voltage (PIV) refers to the maximum reverse bias voltage a diode can handle without breaking down. This voltage is important to consider because when the input polarity reverses, the diode still has the positive voltage of the capacitor on its cathode, resulting in roughly twice the peak input voltage across it in reverse. Therefore, the PIV must be greater than the maximum voltage of the input waveform to prevent the diode from breaking down. This applies to all types of rectification, including half wave, full wave, and bridge.
  • #1
queenstudy
101
0
i read this sentence like a 100 times and i still don't get it please can anyone help me??
PEAK INVERSE VOLTAGE (PIV):
PIV is the maximum reverse bias voltage which can be applied safely to a diode without its breaking down. Beyond this voltage a diode breaks down
they say the PIV must be greater than the maximum voltage of the sin form of the ac generator why?
 
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  • #2
This is so that the diode will not break down when the voltage is reversed and it's supposed to be 'off' - which is what diodes are used for.

(PIV refers to the Max PIV that the diode can stand - not the actual voltage you apply)
 
  • #3
queenstudy said:
i read this sentence like a 100 times and i still don't get it please can anyone help me??
PEAK INVERSE VOLTAGE (PIV):
PIV is the maximum reverse bias voltage which can be applied safely to a diode without its breaking down. Beyond this voltage a diode breaks down
they say the PIV must be greater than the maximum voltage of the sin form of the ac generator why?

When a rectifier diode conducts and it charges a filter capacitor, it charges the capacitor up to the full positive voltage of the input waveform (minus a small diode voltage drop).

Now, when the input polarity reverses, the diode gets a peak negative voltage on its anode, but it still has the positive voltage of the capacitor on its cathode.

So, it has roughly twice the peak input voltage across it in reverse. This voltage situation is called the peak inverse voltage and the diode needs to be able to cope with it without breaking down.
 
  • #4
what about the formula PIX greater than Vm in both half and full rectification why??
thank you guys for the help
 
  • #5
You cannot rely on the two reverse biased diodes sharing the applied volts equally.
 
  • #6
queenstudy said:
what about the formula PIX greater than Vm in both half and full rectification why??
thank you guys for the help

For the same reason as above, if the diode charges up a capacitor, that voltage will add to the reverse voltage across the diode when the polarity from the transformer reverses.

This applies whether the rectification is half wave, full wave or a bridge. (In a bridge, there are two diodes in series when the polarity reverses and as Sophie mentions, they may not share the voltage equally.)
 

What is Peak Inverse Voltage (PIV)?

Peak Inverse Voltage (PIV) is the maximum reverse voltage that a diode or other semiconductor device can withstand without breaking down. It is an important parameter in understanding the capabilities and limitations of electronic components.

Why is PIV important?

PIV is important because it determines the maximum voltage that a semiconductor device can handle without getting damaged. It is crucial in selecting the right components for a circuit and ensuring its proper functioning and longevity.

How is PIV calculated?

PIV can be calculated by multiplying the peak voltage of an alternating current (AC) signal by the square root of 2 (1.414). For example, if a circuit has a peak AC voltage of 10V, the PIV would be 10V x 1.414 = 14.14V. It is important to note that this calculation is based on ideal conditions and in real-world scenarios, other factors such as temperature and manufacturing tolerances may affect the PIV.

What happens if PIV is exceeded?

If the PIV of a semiconductor device is exceeded, it may break down and fail. This can cause permanent damage to the component and potentially lead to circuit malfunctions or failures. Therefore, it is important to choose components with an appropriate PIV rating for the intended circuit.

Can PIV be higher than the peak voltage of the circuit?

Yes, PIV can be higher than the peak voltage of the circuit. This is because the PIV rating takes into account factors such as voltage spikes and surges that can occur in a circuit. It is important to choose components with a PIV rating that is higher than the peak voltage of the circuit to ensure its proper functioning and durability.

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