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-12VDC from +12VDC?

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kasamiko

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Hi,

Can you suggest a simple +12VDC to -12VDC at least 500mA? Preferably with MC34063A.

TIA
 
I was not expecting how complicated it was...:(
 
If you can get 78S40 device, check Fig 15 on page 14 of the AN-920 datasheet suggested by Carbonzit. Perhaps the method can also be applied to 8 pin MC34063A

this appears a good application to give 15V at 500mA, there is a typing error in the schematic that it is 0.5mA.

Reducing R2, 36K slightly, you could set it to 12V. assure that the 68uH coil should be with thicker gauge to be able to carry little over what you need.
all the best.
 
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I was not expecting how complicated it was...:(

It's not! Page9 of the Analog Integrations Corporation PDF datasheet for the MC34063 (DS-34063A-01) shows it is incredibly easy to make a -12v "inverting converter".

It just needs the 34063 IC, a diode, inductor and a couple of caps and couple of resistors. It's as simple as the buck converter circuit.
 
It's not! Page9 of the Analog Integrations Corporation PDF datasheet for the MC34063 (DS-34063A-01) shows it is incredibly easy to make a -12v "inverting converter".

It just needs the 34063 IC, a diode, inductor and a couple of caps and couple of resistors. It's as simple as the buck converter circuit.

... except that that circuit shows an input voltage of 4.5-6V, not the 12V that the O.P. wants to use. (Here's that datasheet.)
 
Beyond the input voltage another issue is the circuit on page 9 of the data sheet delivers an output current of 100 mA and I believe the OP wants 500 mA? Now if that is true for what it is worth the OP seems to want -12 volts from a 12 volt input. I would just consider using one of these and be done with it. The ZUS61212 offers a wide range input voltage of 9 to 18 volts with a fully isolated, regulated 12 volts output. If the OP could get by with .250 amp they are looking at about $20 USD, if the 500 mA is a must they are looking at about $30 USD. While granted this type solution is not for everybody considering everything involved in getting 12 volts at .5 amp I see it as a viable solution in a single package. I am sure with some searching a cheaper DC to DC converter could likely be found for less cost. Not to sat $30 USD is inexpensive but it offers a simple one stop solution.

The circuit in the data sheet and the circuits in CB's link likely could be modified adding to the output to get the desired .5 amp also I guess.

Ron
 
... except that that circuit shows an input voltage of 4.5-6V, not the 12V that the O.P. wants to use.
Then just double the value of the inductor to make that circuit suitable for 12V.
 
... except that that circuit shows an input voltage of 4.5-6V, not the 12V that the O.P. wants to use.
Then just double the value of the inductor to make that circuit suitable for 12V.

... except that 100mA > 500mA, like the man said.

So I wonder about that next circuit in the datasheet, the "Voltage Inverting Converter with PNP Saturated Switch"? Unfortunately, no values given (but I'm sure someone like Simon Bramble could provide them).
 
Compare the two supplies.

The feed back resistors should be the same. Co is the same. C1, Ct same. Rs should be 2x to move from vin of 6 volt to 12 volts then it should be cut to 1/5 to increase the current. L=220uh 1 amp. D1=30 to 50 volts 1a maybe 1 amp. Q1 fast switch 30 to 50 volts, it should have good gain at 600mA.
 
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