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+/- Output Power supply design help

Kyle Aven
Intellectual 950 points
Other Parts Discussed in Thread: UC3843, TPS54160, TPS54260, TPS60400

I do not have much experience in power supply design and need help. I am looking for a way to take Vin= 10-15V and create Vout= +/- 30-40V. The Iout needed would be a max of +/- 100mA. Any help would be very much appreciated. I have looked through a lot of designs from TI and havent had much luck. The more effecient the better.

 

thanks for your time

  • 0
    Prodigy 40 points

    You will need a transformer to get the positive and negative voltages along with the voltage increase.

    Check out UC3843 data sheet  for the flyback topology which shows an example.

    A push pull drive IC like 3525  can also be used accomplish the job.

     

  • 0 in reply to avais qureshi
    Intellectual 950 points

    Do you know of any designs that arent as complicated? And maybe one that doesnt use a transformer

  • 0 in reply to Kyle Aven
    TI__Guru**** 150830 points

    I moved this post to the non-isolated forum, since you don't want to use a transformer.

    This app note does what you need I believe: http://focus.ti.com/lit/an/slva369/slva369.pdf  Depending on what Vout and Iout combinations you need, you may be able to use the TPS54160.  If you do end up needing more power, the TPS54260 is pin-to-pin and will also work.

    There is even an EVM for this topology, http://focus.ti.com/lit/ug/slvu374/slvu374.pdf.

  • 0 in reply to Chris Glaser
    Prodigy 40 points

    TPS54160 is a buck regulator where as requirement is for boost and inversion. Perhaps an initial boost stage will solve the problem.

    However looking an other way, because current requirement is 3ma only Charge pumps like TPS60400 can come to rescue.

    Check this out  http://focus.ti.com.cn/cn/lit/ds/sgls246a/sgls246a.pdf     and then find a suitable IC which meets input and output

    voltage requirements.

     

     

  • 0 in reply to avais qureshi
    TI__Guru**** 150830 points

    In this app note, http://focus.ti.com/lit/an/slva369/slva369.pdf, the TPS54160 buck regulator is being used as an inverting buck boost supply.  Then, a second winding is added to the inductor (a coupled inductor) to generate the positive voltage.  This is very similar to a flyback topology.  So, with that app note, a buck regulator can be used in an inverting buck-boost/flyback topology that generates the needed +/- rails.

    Did you have another 3 mA design, different from Kyle's?

  • 0 in reply to Chris Glaser
    Prodigy 40 points

    No 3mA was a mistake.

    Gave it another look, Suggested TPS54160 solution is good. However a coupled inductor will be an exercise as good as a flyback transformer.

    If a suitable Charge pump is not available then TPS54160 solution can be followed.

     

     

  • 0
    Intellectual 315 points

    Hey Kyle! I'm a little new to power supply design myself! I've been doing it the "old school" way...I have some old paperback books about power supply design copyrighted in the 1960's. They show several high voltage supplies for running vacuum tubes and they even have some with vacuum tube rectifiers and regulators. They also go into the "newer" transistor supplies with diode bridge rectifiers. I have been able to use a few of the circuits using a center-tapped secondary transformer. By connecting the top and bottom AC wires to the AC inputs of the bridge and using the center tap for a ground. This allows me to use the POS output/GND for a positive rail and the NEG output/GND for a negative rail. The positive and negative terminals can still be used for full secondary DC voltage. I’ve tried some of the "old fashioned" capacitor input and choke input filters, and they work pretty good...they're just a little bulky!

    I have also been looking for IC's to use as regulators and also for DC/DC converters to give dual polarity outputs. The DCP02 series seems to fit the bill. There are several that give dual polarity and the data sheet shows that the outputs can be connected in series to give a single polarity doubled voltage. They are rated for 2W and they can also be connected in parallel to give double the power output.

    I would also like to know if you or anyone else has any circuit ideas for the DCP02 series, they seem to be very useful.

     

     

  • 0 in reply to David Poston
    Intellectual 950 points

    I have never used the TI DC/DC converters before. I have used the V-Infinity ones though with great success. I'm sure the TI ones are just as useful. The design I am currently redesigning used DC/DC converters to accomplish +/- 30V output. I used two +/- 15V 2W converters. The design works, but I believe that it can be done better. Stacking a handful of modules to accomplish a working prototype is fine, but i think our finished product should be a little more refined.. I am actually finishing this design up with two Linear LT3958 converters. Very simple design to achieve the +/- 40V rails. I also need +/-12V rails but that will be easy to achieve with just about anything.

    Thank you all for your time and your help. This is the first online community that i have actually found being a member of useful.