use of DC to DC converter..

[peeyushsigma]

why we use DC to DC converter when we have DC voltage already...

 

[In2Dusk]

Because they can change voltage of input to some other needed value. For example this one **broken link removed** can convert anything from 4-30V to 3.3V.

 

[jeffrey samuel]

most dc dc converters allow you to provide higher voltage op from the available lower ip values and vice versa

 

[peeyushsigma]

Because they can change voltage of input to some other needed value. For example this one **broken link removed** can convert anything from 4-30V to 3.3V.

this can be also be done by the voltage regulator ICs like 78XX...

is dc to dc converter and voltage regulator are same...

 

[In2Dusk]

DC DC converters and voltage regulator are similar in the matter that they transform voltage of one value to another, however most DC DC converters, firstly convert DC input to AC which is easier to transform, this is how they can produce higher voltage output than is their input. Voltage regulators usually use opamp to regulate the input to lower value, their output is always less than input voltage.

 

[jeffrey samuel]

the fact is regulation and conversion follow different method to give the desired op for the ip dc voltage

they are more like brothers in operation following different protocols

 

[peeyushsigma]

the fact is regulation and conversion follow different method to give the desired op for the ip dc voltage

they are more like brothers in operation following different protocols

thank u ...for ..replying..
i just want to ask ...that if i want to convert 9v dc to (3.3v or 5v dc) which one i use #dc to dc converter or # regulator...
please explain ..

 

[jeffrey samuel]

there is a very little difference in voltage so i think it is better to go with a regulator rather than a converter

 

[Raza]

DC to DC converters can transform from lower to higher voltage where as Regulators can from higher to lower values only. In many cases the DC/DC converters also eliminate the noise on main voltage line. In your case it is better to use 3.3 volts or 5.0 volts regulators. They are cost effective also. The use of these regulators do consider current value, too.

 

[jeffrey samuel]

yeah if need is known it is determined to go with the more economic design

 

[tpetar]

thank u ...for ..replying..
i just want to ask ...that if i want to convert 9v dc to (3.3v or 5v dc) which one i use #dc to dc converter or # regulator...
please explain ..

You can use linear voltage regular or switching voltage regulator for that job, my thinking for this is better linear.

You have linear voltage regulators :

78L05 100mA
7805 1A
78S05 2A
78T05 3A

78L3.3 100mA
LD1117V33 0,8A

 

[vedagarbhamsandeep]

you may also drop the DC voltage by having a length of wire.

VD (Voltage Drop) = 2 IRL / 1000

I = Load Current (A)
R = Resistance Factor
L = Length of cable.

As its a small drop of 3-4V which is required, I thought this may help as well. Any suggestions / critics, most welcome.

 

[jeffrey samuel]

you may also drop the DC voltage by having a length of wire.

VD (Voltage Drop) = 2 IRL / 1000

I = Load Current (A)
R = Resistance Factor
L = Length of cable.

As its a small drop of 3-4V which is required, I thought this may help as well. Any suggestions / critics, most welcome.

what do you mean by resistance factor ????

if it is resistivity of the material of the wire then let us say copper wire it has a resistivity of as shown in the link

https://hypertextbook.com/facts/2004/BridgetRitter.shtml

if i am not wrong then the math says something very very small and if it is conductivity of the cu wire then it is about 1 megameter long

what are you trying to say by that

such long wires then it becomes unwieldy

 

[vedagarbhamsandeep]

No No .. I am not asking you to use a super / good conductor.

We could use a lossy power cable to obtain this drop .. not sure if anything this type is available though.
I have not done that but have noticed that when we pull long cables from the solar panels (say 10m or so) for a DC system, we notice a drop in voltage of 2-3V (as compared to voltage at the terminals of the panel).

Regarding resistance factor, not sure but I suppose it would be related to the load (maybe cable R + load or either only load). need more info on the same .. lets wait for some expert to comment on this !

 

[jeffrey samuel]

hoping for it

 

[DeLorean]

The DC to DC converter can increase your current output if your input has a higer voltage than your output. The linear regulator will just keep the same current but disipate the extra voltage as heat.

 

[tpetar]

The DC to DC converter can increase your current output if your input has a higer voltage than your output. The linear regulator will just keep the same current but disipate the extra voltage as heat.

Hi,

How you mean to increase current ?

How you mean to keep existing current ?


Complete design use some transformer with some capabilities, also graetz (rectification bridge) have some capabilities, voltage regulators have some capabilities lets say LM2575T-3.3 1A, LM2679S-3.3NOPB 5A, LT1584CT-3.3 7A, LT1086CT-3.3 1,5A, 78S05 2A, LM317 1,5A, LM338K 5A, LM1083 7,5A, LT4970A 10A, ... all with their capabilities.

He need from 9V to make 3,3V or 5V. All regulators can done this job linear or switcher. But you must watch on switchers needed stanby current !.

:wink:

 

[DeLorean]

Converters typically run 80 to 90% efficiency. So say you are drawing 1 amp on the 3.3 volt (3.3 watts). Then your 9 volt supply current would be 403 ma (3.63 watts) at 90% efficiency.

Using a linear regulator would draw 1 amp at 9 volts on the supply. It would need to dissipate 5.7 watts of heat.

Now if you have very low current requirements then a linear regulator is the way to go.

 

[tpetar]

@DeLorean

What is needed standby current for switchers, also and linears in some design have minimal required current ?

 

[DeLorean]

@DeLorean

What is needed standby current for switchers, also and linears in some design have minimal required current ?

Good question. You would have to look it up on the data sheet since I don't think all are the same. Some may have a shut down pin. I would assume you are shutting off the input voltage to power down the circuit anyway.