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Voltage Regulator/ Voltage Reference

Discussion in 'Electronic Basics' started by GraemeC, Mar 22, 2007.

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  1. GraemeC

    GraemeC Guest

    Im trying to create a +/- 2.5V supply from a +/-5V. I have a couple
    of 2.5V voltage references. Am I right in assuming that I need to get
    hold of a -2.5V reference? I did read an article that showed how I
    could use an inverter but I don't have any of those either.

    There seems to be a gap in my knowledge because I don't really
    understand the difference between a voltage reference and a voltage


  2. If your 2.5 volt references are shunt type (two terminals
    that hold 2.5 volts when an externally limited current is
    passed through), you can use two of them to regulate a small
    (milliamperes) supply. If you want a more significant
    current from these supplies, you should use actual supply
    regulators. The adjustable LM317 and LM337 pair can be set
    to 2.5 volts output with a pair of resistors.
  3. You need a low-impedance driver set at 2.5V relative to your current
    ground and this new low impedance driver needs to source or sink
    (two-quadrant, if my hobbyist knowledge of terms is close to right.)

    You don't say what your _current_ requirements will be. There's a
    simple answer if you are talking about a few tens of mA. This is the
    TLE2426 "rail splitter." Also, an opamp set up with the 2.5V
    reference to its (+) input and its (-) tied to its output, which
    drives the new center point "ground" might be okay, assuming your
    opamp can deliver the current requirements you are looking for. (Or
    just use a resistor divider instead of the 2.5V reference, to the (-)
    input.) A discrete splitter could be formed out of transistors, too.
    A reference usually has a very small _current_ drive capability -- not
    uncommonly in microamps -- to name one important difference.

  4. Sorry, I meant (+), not (-).

  5. Jamie

    Jamie Guest

    use a 2425 and turn it around.
    the COM will be the - line and (IN) your common .
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