Schottky Barrier

[parker]

1. What is the main function of this Diode?
2. What application it is best suit?
3. What makes it different from a standard diode?

 

[blueroomelectronics]

Homework assignment?

 

[parker]

Homework assignment?

yes, and need a deep understanding about barriers function

 

[MrAl]

Hi,

This kind of diode can switch off much faster than a standard rectifier diode. It's used where high speed switching is a necessity.
It also has a lower forward voltage drop. For example, anywhere from between about 0.2 volts to 0.5 volts roughly, as compared to 0.7v for a regular diode.
However reverse voltage ratings are often much lower than standard diodes.

 

[parker]

However reverse voltage ratings are often much lower than standard diodes.

i'm a newbie on this field kindly give more details on how "REVERSE VOLTAGE RATINGS" works

 

[MrAl]

Hello again,


The reverse voltage rating is the rating the diode can take if the voltage across it is reversed. When the voltage is not reversed the voltage is less than 1v or about that, but when the voltage is reversed the diode does not conduct much so the voltage can go very high. If you have a diode rated for 50v and you apply 100v you burn the diode out. If you apply only 30v the diode does not burn out. It's quite simple really...anything under the rating and the diode still works, but anything over the rating and the diode burns out (and can not be fixed).

 

[crutschow]

Because of their lower forward voltage drop and fast reverse recovery time, Schottky diodes are often used in switching power supplies for better efficiency.

 

[crutschow]

Homework assignment?

I would think that would not be unusual in the "Homework Help" forum.

 

[parker]

Because of their lower forward voltage drop and fast reverse recovery time, Schottky diodes are often used in switching power supplies for better efficiency.

can i use this as a replacement for a standard diode to bridge a power source?

 

[crutschow]

can i use this as a replacement for a standard diode to bridge a power source?

Do you mean as a bridge rectifier in an AC to DC power supply? If so, the answer is yes as long as the diode voltage and current ratings are sufficient.

But unless it's a very low voltage supply, there is not much advantage in using Schottky diodes for such an application.

 

[parker]

Do you mean as a bridge rectifier in an AC to DC power supply?

yes (e.g. input 220VAC and secondary 36VAC center tapped)
will STPS2045CT works for this type of transformer?

 

[crutschow]

yes (e.g. input 220VAC and secondary 36VAC center tapped)
will STPS2045CT works for this type of transformer?

If you use it as a full-wave rectifier with the transformer center-tap grounded, and you current is less then 10A, it should work fine. But for this application it has little advantage over a standard junction silicon rectifier.

 

[parker]

If you use it as a full-wave rectifier with the transformer center-tap grounded, and you current is less then 10A, it should work fine.

is this right?

 

[crutschow]

That looks correct.

 

[parker]

That looks correct.

does it mean you're not so sure?

 

[crutschow]

does it mean you're not so sure?

It means the basic circuit is correct as drawn, but it's actual performance depends upon your application. For example, if you draw the full 85VA from the output or over 4A, then the ripple will be over 4V with the capacitor filter value you show. I don't know if that would be acceptable for your requirements.

 

[parker]

if this things happen...

if you draw the full 85VA from the output or over 4A, then the ripple will be over 4V with the capacitor filter value you show.

do i need to replace the caps with higher capacitance like 20k uF or get a smaller one?

 

[crutschow]

if this things happen...

do i need to replace the caps with higher capacitance like 20k uF or get a smaller one?

Ripple goes down as capacitance goes up. Doubling the capacitance will cut the ripple approximately in half.

 

[parker]

thanks a lot! it's a great help for a newbie like me