I am currently designing a project where I need +/- 12V to power the circuit I have built. The boost converter I have does not supply enough current (only 42mA out), thus dropping my supply voltage to zero. I need a circuit or converter that will take a 5V input and convert it to a +/- 12V to power my chips, but also give enough current. Any suggestions would be great, thanks.

 

How much current would be enough?

 

Depending on your current requirements something like this -

https://www.ebay.com/itm/5V-6V-9V-1...ac2dab18:m:m_FZppqtc_npxIw2m2fBw9A:rk:16:pf:0


Regards, Dana.

 

How much current would be enough?

Right now the DC/DC converter I have is outputting 42 mA, I need more in the range of 100-200mA minimum.

 

Right now the DC/DC converter I have is outputting 42 mA, I need more in the range of 100-200mA minimum.

What is the maximum curremt that you need?
There is no point in us looking for a converter that will supply only the minimum current.

 

What is the maximum curremt that you need?
There is no point in us looking for a converter that will supply only the minimum current.

400mA is the max current I need.

 

400mA is the max current I need.

How did you come up with that number?

 

400mA is the max current I need.

400 mA on dual 12V outputs will draw over 2 Amps from the 5V power supply!

 

400 mA on dual 12V outputs will draw over 2 Amps from the 5V power supply!

You lost me there. I don't even see where 12V outputs are mentioned. Is it the +/- mention? Still how are you getting there will be 2amp draw?

 

.4A on 12 V = 4.8 watts x 2 (two outputs) = 9.6 W / 90% efficiency
= 10.6 W on a 5V supply = > 2A.

Regards, Dana.

 

So it is the DC to DC conversion that causes the higher current consumption? I was not aware of that. I thought tha the circuit consumed what it consumed. I do understand there are power requirrements to run th e convertor.

 

So it is the DC to DC conversion that causes the higher current consumption? I was not aware of that. I thought tha the circuit consumed what it consumed. I do understand there are power requirrements to run th e convertor.

If you increase the voltage at the output then you also increase the current needed from the input. This is so whether it it is boost converter for DC or a transformer for AC.

Power out will always be less than power in.

 

If you increase the voltage at the output then you also increase the current needed from the input. This is so whether it it is boost converter for DC or a transformer for AC.

Power out will always be less than power in.

I know that. What I can't understand is why the current requirements increase so dramatically. and TS is decreasing voltage needed not increasing. Or is it that it doesn't matter? since he is decreasing that is power being wasted so the calculation needs to occur on the 12V side?

 

TS is taking a 5V input and generating ±12V at the output - so 5V must become 24V. This is almost a five fold increase in voltage from input to output. To get 400mA at the outputs, a five fold increase in that current will be needed at the input and that is 2A. It will likely need more input current than that allowing for the inefficiencies of the converter.

 

What is the maximum curremt that you need?
There is no point in us looking for a converter that will supply only the minimum current.

TS is taking a 5V input and generating ±12V at the output - so 5V must become 24V. This is almost a five fold increase in voltage from input to output. To get 400mA at the outputs, a five fold increase in that current will be needed at the input and that is 2A. It will likely need more input current than that allowing for the inefficiencies of the converter.

2.5ADC ,the source should not be used at the maximum current rating sometimes, so it might be better 3 or 4ADC.

 

Energy Out = Energy In - Losses.

Regards, Dana.