from 5 volts to ± 9 to 12 volts

[cimo]

mc34063 tapped

hi
i need to boost 5 volts up to 9 to 12 volts (charge pump, IC ?) (maybe 10 volts using a an IC votage doubler?) and then to get a bipolar voltage, as to say i need to transform 5 volts into ± 9 to 12 volts.
Thanks
simone±

 

[mohammed.peer]

hi
i need to boost 5 volts up to 9 to 12 volts (charge pump, IC ?) (maybe 10 volts using a an IC votage doubler?) and then to get a bipolar voltage, as to say i need to transform 5 volts into ± 9 to 12 volts.
Thanks
simone±

you can do one thing use pull up resistor to enhance output voltage

 

[lats]

you can do one thing use pull up resistor to enhance output voltage

was that a joke????

 

[dunn]

What o/p current do you require?

 

[dfullmer]

Hi,

Same question as DUNN. All of this can be done with simple switchers if the power requirments are there. You have 5 volts! How much current is availible? You need +/- 9 volts. How much currentwill this need? You need 12 Volts. How much current will this need? Give us a little more detail and we can get you going.. If you don't know exactly how much current for each try and describe what it is driving or take a guess at the current demand for each.

regards

dfullmer

 

[cimo]

got sick of pulling up all those resistors !!!!

Ok sorry i meant to write it on my post but i eventually forgot about that.
The source is a usb hub so it can feed 500 mA but my circuit is already asking for some of it, that s what we have on the source.The final voltage will feed an operational amplifier, so i estimate that i won t need anyhting more than 50 mA, it will be probably less.
IMPORTANT: i don t need 9 and 12 but something between 9 and 12.
As you can understand i need a low power circuit that will "suck" as little as possible.
I would also add that there is only ! electronic shop here where i live and the ICs if any should quite popular.
Thanks
simone

xxxxtestxxx

 

[Koson]

Try sg3524 (or any SMPS ICs) looking for cct in datasheets.

so many choice to finish ur work:
choice #1. Boost converter with SMPS [to between 9 to 12 Volt] in single pole and then generate neg voltage with sw/cap

choice #2. single SMPS and + 0 - secondary coil x'former

choice #3. double SMPS with pos and neg voltage on each.

apologize for my english.

Regard.

 

[kinjal_book]

bipolar voltages can be gained by the x'mer connections(center tapped) itself
have 0v as ground of the circuit and use positive voltage end for getting positive voltage so..it will be input of positive voltage regulator and other end(negative end of x'mer) will be input of negative voltage reg

 

[cimo]

hi
i took me a while to understand what x'mer and x'former were but then i got it ..:idea:
anyway i don t have any transformer because i can use only the 5 volts feed by the usb hub.That s why i need to boost the voltage: i need around the double of the input voltage to drive an opamp.
txxxx ssoo much
simone

 

[dfullmer]

Hi,
Does your op amp need to output negative voltages. If not have you considered using a single supply op amp? Otherwise go to national semiconductor web site, or linear Technology web site and look for a simple single chip switcher that will give you both a negative and positive voltage. You will need to produce a boost circuit using inductors and flyback diodes but it is completely doable. get the parts delivered to you from digikey on line and there you go.

The other possibility is to buy a dc to dc converter that has already done all the work for you.

https://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=100595&Row=165367&Site=US

couple hundred in stock and they are 10 bucks


good luck dfullmer

 

[artem]

There is little known trick to use max232 or similar rs232 drivers as charge pump converters to do this work. Play with capacitors for output current. If you need slightly more than chip provides - put 2 chips in parlallel through diodes to prevent current backflow .

And pay attention to the pins where final output voltages are filtered by capacitors - those are place where you will get needed voltage .

 

[cimo]

hi
about the application i still don t know it, i probably need to offset from 0,25 to 0 and the source is a little above +5 volts while i need to reach a clear from 0 to 5.
The 232 idea seems to be very good because i went to the shop and they don t have anything at all just a few opamps, and shipping things to where i live is quite expensive not really worth it for a few ics.
I ve also found a 7660 at home it could be usefull.
Can you please tell me more about the 232 solution? i have a couple of them at home but i can t really understand your explanations i am not so expert!!
thnaks simone

 

[artem]

Simon, it is straightforward and simple. Have a look to max232 standard connection example . Pay attention to
pins 6 and 2 . There are one capacitor per each pin connected to ground or to +5 V. Usually nobody uses them when working with rs232 level conversion . These pins are output of max232 internal charge pump dc-dc convertor. Pin 6 is -10V dc-dc charge pump output an pin 2 is +10V internal charge pump convertor output . You can use them as power supply for your application. The only restriction is curretn can be drawn from these lines. If current is to high - voltages will decrease . Max current to draw from max232 depends on capcitor values and charge pump transistors current limit capabilities (switch impedance and max allowable current). You can play with increasing capacitor values and trying to increase current drawn from it, but it is up to your responsiblity if chip will be damaged by overdrawn current). Or you can try to use 2 max232 connected in parlallel via diodes if current supplied wont be enough.

 

[nguyennam]

Cimo,
I think I understand your case, as you need the dual supply of ±9...12V from the USB rails. Theoretically there are many circuits to build based on the principle of converting DC current to AC current, but the problem is the source is USB and maximum current is about 500mA max. Although your need of the new supply is only 50mA but you have to ensure that there will be no overdraw current from USB, then it limits the choice of circuits.
The MC34063 is a very popular universal switching IC, could you try it. The circuit will be very simple and easy to build. MC34063 datasheet, circuit example and design notes are available on ONsemi.com website.
Hope this will help.
Nguyennam

 

[Ajish Babu S]

The figure below shows circuit of the simple voltage doubler and inverter.
I don’t know it is use full for you.

Working of Voltage Doubler

The circuit diagram for voltage Doubler is shown below. The circuit consists of three capacitors of 1μF and four control switches. Input voltage is connected across the capacitor C1. There are two steps of energy transfer. During the first step, Switches SA1 and SA2 are closed and SA3 and SA4 are open. Charge now transfers from C1 to C2 until their voltages become equal in value and polarity. During the second step, switches SA3 and SA4 are closed and SA1 and SA2 are open. Now the charge transfers from capacitor C2 to C3.till both attain the same charge.
When these two steps are repeated sufficient no: of times, the output capacitor C3 attains the charge of the input capacitor C1

Nodes A and D are connected to +5V power supply.
We have the equation

VA-VB = VC-VD

VA=VD=5V
VB = 0V

VC = VA+VD-VB
=10V

The output is taken from node C which is the double of the input voltage.

Working Voltage inverter:

The circuit diagram for voltage inverter is shown below. The circuit consists of three capacitors of 1μF and four control switches. Output voltage from the doubler is connected across the capacitor C4 The steps of energy transfer are same as that of doubler. During the first step, Switches SB1 and SB2 are closed and SB3 and SB4 are open Charge now transfers from C4 to C5 until their voltages become equal in value and polarity. During the second step, switches SB3 and SB4 are closed and SB1 and SB2 are open. Now the charge transfers from capacitor C5 to C6.till both attain the same charge.
When these two steps are repeated sufficient no: of times, the output capacitor C6 attains the charge of the input capacitor C7

Nodes F and G are connected to ground potential.

We have the equation

VE-VF = VG-VH

VF=VG=0V

VE=10V

VH= -VE=-10V

The output is taken from node H which is of opposite polarity of input voltage.