Negative voltage in circuit

Discussion in 'General Electronics Chat' started by Vindhyachal Takniki, Feb 12, 2015.

  1. Vindhyachal Takniki

    Thread Starter Member

    Nov 3, 2014
    349
    6
    I need negative voltage in my circuit with common ground wrt positive voltage

    1. One option is to generate negative supply by placing a full- bridhe & then using 7905.
    It includes lots of extra components to be used.
    2. Another option is to use TC7660. Simple to use & works good. Only problem is its output voltage falls with current. For a load current of -10 mA and a supply voltage of +5V, the output voltage would be -4.3V.

    3.I need to generate regulated -5V,-2.5V&-1.8V

    4.Any other way to do that?
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,813
    1,105
    You could use a SMPS with an isolated output. Its more-positive output terminal would connect to the common ground.
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,056
    3,245
    How much current do you need for each output?
     
  4. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
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    There are plenty of negative rail inverter circuits online, and nearly as many off the shelf chips that do the job - or it can be as ready to hand as a 555 with a charge-pump on the output.
     
  5. BobTPH

    Active Member

    Jun 5, 2013
    789
    114
    A buck-boost converter will produce a negative voltage.

    Bob
     
  6. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
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    An inverter that outputs the opposite polarity to the input doesn't have to be buck-boost topology to span output voltage both above and below the input voltage.
     
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