How do I use this DC/DC?

Discussion in 'General Electronics Chat' started by Seric, Aug 3, 2014.

  1. Seric

    Thread Starter New Member

    Oct 20, 2013
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    I want to use a SH01S0503A DCDC converter in a circuit. It receives 5V in and outputs 3.3V. Here is the datasheet. I want to use the single output version.

    But I am confused about the pin connections listed at the bottom of page 4. There are 4 connections: +Vin, -Vin, +Vout, -Vout. The only other DCDC that I have used had Vin, Vout, and GND, so this one is confusing me.

    So how to I hook up this one? I'm guessing the negatives are just for the case where I want to use negative voltages. So I would just put my 5V into +Vin and get 3.3V from +Vout? Where's the ground?
     
  2. Lestraveled

    Well-Known Member

    May 19, 2014
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    This is an isolated power converter. The input is not connected to the output unless you connect them. For the input you would apply 5 volts across +Vin and -Vin. The output would be +Vout and -Vout. This is an isolated converter so you can produce a -3.3 volts as well as a +3.3 volt output. All four pins must be connected to something.
     
  3. Seric

    Thread Starter New Member

    Oct 20, 2013
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    So I need to have both a +5V and -5V source for it to work?
     
  4. Lestraveled

    Well-Known Member

    May 19, 2014
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    No. +5 volts connects to +Vin and ground connects to -Vin.

    If a data sheet says it is a 5 volt input, the input pins will be indicated as +Vin and -Vin. +5 volts goes to +Vin and ground goes to -Vin. It is not saying that the part runs on +5 volts and -5volts. It is just indicating polarity. The same is true with the output.
     
  5. Seric

    Thread Starter New Member

    Oct 20, 2013
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    Ah I see. Then I presume -Vout also connects to ground?
    I think that part of why I got confused is that I just forgot that voltage is measured in reference to something else. Rookie mistake!
    Unfortunately the datasheet doesn't include an example application schematic.
     
  6. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    Yes, I got confused too. If you connect -Vout of Single Output (Pin 4) to ground, would it be the same as connecting it to common? If yes, then we are looking at the dual output configuration according to the table in the end of the datasheet. If that is right, then Pin 7 will have +3.3 volts. And Pin 5 will be -3.3 volts.

    It seems to me that you just take your +3.3 volts from Pin 7, ignore or ground Pin 5. So you have +5 volts going in, +3.3 volts coming out.
     
  7. crutschow

    Expert

    Mar 14, 2008
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    3,229
    According to the data sheet, this is an isolated supply. Thus you can connect the input and output to separate grounds, if needed, but connect them to a common ground if isolation is not needed (or wanted).
     
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