Exploring Series vs. Parallel Diode Configurations for Circuit Layouts

Hello, gentlemen, I have such a paper for tomorrow.

The professor asked me to give the differences between parallel and series connection of semiconductor diodes. Needed for layout analysis.

and I can't buy the manual for this item yet.

Porach. although. I was also looking on the Internet .. and I found nothing interesting: d

Let it not be that I am a lazy or a retard .. Thinking logically ...

with parallel connection of diodes .. we lower the voltage threshold at which the diode will work ... with serial one, this threshold should rationally increase, are there any other fundamental differences
?

best regards bakss

Dear friend
Well, the thing about diodes is that they do not behave like a traditional resistor, because they are semiconductor elements.
You could write about the differences for a long time, but I will try to draw the most important ones.
For serial connections:
1- all diodes must be connected with the correct polarity, i.e. the cathode of the first to the anode of the second diode, etc.
2- can be powered from direct current, if the direction of the current flow is consistent with the polarity of the diodes, or alternating current (for frequencies over 25 Hz it will give the impression of continuous lighting)
3 - as you know, the diodes are powered by a specific current, not voltage, so you need to choose a resistor so that the current matches the receivers (diodes)
R = (Uz - x * 0.7) / Id, where R - power supply resistor, Voltage Uz. power supply, x number of diodes, Id - diode current
4 - one more note, this way you can only connect LEDs with the same light currents
For parallel connections
1 - Each diode has its own resistor, matched to its operating current, it can be one resistor for all of them, provided that they have the same parameters
2 - in order for all to light, they must be connected in the same polarity and in the direction of the current flow, to a DC voltage source, or any connection to an AC source of> 25 Hz

If I did not write something here because I forgot, please complete this post;]

Hello,

Elmo_pf wrote:

Dear friend
Well, the thing about diodes is that they do not behave like a traditional resistor, because they are semiconductor elements.
You could write about the differences for a long time, but I will try to draw the most important ones.
For serial connections:
1- all diodes must be connected with the correct polarity, i.e. the cathode of the first to the anode of the second diode, etc.
2- can be powered from direct current, if the direction of the current flow is consistent with the polarity of the diodes, or alternating current (for frequencies over 25 Hz it will give the impression of continuous lighting)
3 - as you know, the diodes are powered by a specific current, not voltage, so you need to choose a resistor so that the current matches the receivers (diodes)
R = (Uz - x * 0.7) / Id, where R - power supply resistor, Voltage Uz. power supply, x number of diodes, Id - diode current
4 - one more note, this way you can only connect LEDs with the same light currents
For parallel connections
1 - Each diode has its own resistor, matched to its operating current, it can be one resistor for all of them, provided that they have the same parameters
2 - in order for all to light, they must be connected in the same polarity and in the direction of the current flow, to a DC voltage source, or any connection to an AC source of> 25 Hz

If I did not write something here because I forgot, please complete this post;]

the entire elaboration above is off-topic because it talks about connecting LEDs, not ordinary semiconductor diodes, which the author of the topic asks about.

Elmo_pf I suggest that you look for a description (and you will find it for sure) current - voltage characteristics one diode and using the knowledge of Fundamentals of Electrical Engineering he wrote the correct conclusions himself.

Regards

and I already have ...

parallel connection of the diodes increases its current carrying capacity

series connection, it is used in order to have a higher allowable reverse voltage
its scattering of reverse characteristics can lead to significant differences in the voltage distribution on individual diodes. It is therefore necessary to use decomposition systems
voltage, e.g. resistive-capacitive dividers

It is so for those who would not have literature ;)

thanks to Quarz for the correct guidance.

Hello,
I will add the diodes to be connected in parallel. Here, too, the uneven conduction characteristics of individual diodes are the cause of their uneven load, i.e. uneven current distribution in individual diodes.
Therefore, for diodes with low forward currents (up to 1 AND ), series equalizing resistors are switched on, on which the voltage drop, for the rated diode current value, is from 25% to 50% of its forward voltage.
Of course, for diodes with significant forward currents, switching on such resistors does not make any sense, because it is difficult to perform and increases the power loss.
Here, other methods of equalizing the current flow are used, namely, first of all, a common heat sink to equalize the temperature of the junctions of all diodes connected in parallel.
And it is very important because the temperature coefficient of the semiconductor diode's forward voltage is negative, which means that with identical characteristics, the diode with a higher temperature of its PN junction (lower value of the forward voltage) will be loaded more.
Therefore, the maximum permissible average conduction current of diodes connected in parallel is approx. 80% of the current value that would result from the multiplication of the maximum conduction current of one diode and their number in a parallel connection.
Of course, for a parallel connection, diodes of the same type should be used, and they are often selected due to the equality (within a certain permissible tolerance) of their characteristics in the direction of conduction.
Here, too, the equalization of the flow of currents is influenced by the lead resistances, and therefore the way of parallel connection of the diodes should be analyzed and selected so that these resistances are equal.

Regards

Sorry, but I'm on a different topic. Who will finally correctly write the plural form of the word "dioda" at least once. Knowledge of Polish spelling asks for vengeance to heaven.

Certainly not me, because I segall ...

Dear colleague Quarz, I sincerely apologize, the easiest way in the world was to help a young electronics engineer, that I entered my arguments, thus losing the plot. I bow my head and thank you for pointing out my mistake. I have always appreciated the positive criticism that teaches accuracy.
Regards Elmo_pf