Voltage Splitter? Question?

[average_male]

Hello everyone,

I am fairly new to electronics and have a seemingly basic question:

1) If I have two devices that require two different voltages, say 3v for one device and 5v for another on the same board, how would one supply these different voltages off of one 12v power supply?

I would guess two voltage regulators? One that takes in 12v and out puts 3v and another that takes in 12v and out puts 5v?

2) What if my power supply was 5v, would I then need just one regulator for the step down to 3v, or do I need to consider that the regulator will drop the line in of 5vs down some?

What is this referred to in electronics? Voltage splitting? Any resources would be appreciated.

Thanks!

 

[Grossel]

Hello everyone,

I am fairly new to electronics and have a seemingly basic question:

1) If I have two devices that require two different voltages, say 3v for one device and 5v for another on the same board, how would one supply these different voltages off of one 12v power supply?

I would guess two voltage regulators? One that takes in 12v and out puts 3v and another that takes in 12v and out puts 5v?

Yes, two independent regulators should do.

2) What if my power supply was 5v, would I then need just one regulator for the step down to 3v, or do I need to consider that the regulator will drop the line in of 5vs down some?

It all depends on the power source and it's output impedance.

 

[average_male]

Thanks Grossel,

Just a follow-up question, if I may:

What is this called when you have two (or more) different lines of voltage within the same board?

Also, what if you have a 3v supply and need both 5v and 3v lines and the supplied 3v has enough impedance to cover the draw for both of these lines. What is the method called for increasing voltage? voltage multiplier? How is this done? Through the use of capacitors?

Thanks again.

-Moe

 

[Boncuk]

Hi,

voltage multipliers are commonly used for AC like cascaded rectifiers and capacitors.

To increase DC voltage commonly step-up converters are used.

Boncuk

 

[average_male]

Boncuk,

Thanks for taking the time to answer my question. I never knew they made step up converters. So in theory I can have 3v as input and use a step-up converter to say 9V? WIthout capacitors? Very cool.

Thanks,
Moe

 

[Roff]

Boncuk,

Thanks for taking the time to answer my question. I never knew they made step up converters. So in theory I can have 3v as input and use a step-up converter to say 9V? WIthout capacitors? Very cool.

Thanks,
Moe

Look up "boost converter". You will need capacitors.

 

[average_male]

Roff,

Thats what I was looking for, "boost converter", cool!

Thanks for your input. Much appreciated.

-Moe

 

[Roff]

Be aware that the input power to your boost converter will be more than your output power. If you need 5V@1A, your input will be 3V@1.67A, divided by the efficiency. If the efficiency is, for example, 90%, you will need 1.85A from the 3V supply.

 

[average_male]

Thank you Roff,

So Supply [3V@1.85A] <=> [5V boost converter @ 90% efficiency] = 5V@1.67 output.

That is good to know. I assume different boost converters have different efficiency ratings. Makes sense.

Thanks for that detail, saved me from some headaches.
Moe

 

[Roff]

Thank you Roff,

So Supply [3V@1.85A] <=> [5V boost converter @ 90% efficiency] = 5V@1.67 output.

No!
Supply [3V@1.85A] =>[5V boost converter @ 90% efficiency] = 5V@1A output.

 

[average_male]

Thanks Roff. Got it.