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TPS5430 -- -12V to -5V at 0.5A

Angela
Intellectual 595 points
Other Parts Discussed in Thread: TPS5430, LM337

Hi support,

is TPS5430 a good fit for negative input and output application? What's the better part to use?

  • 0
    TI__Guru**** 164606 points

    Hello Angela.

    One option is the LM337. It is a adjustable negative linear voltage regulator.
    It is very simple to use, but it will dissipate (12V-5V)*0.5A = 3.5 Watts.

    If the -12V input is a floating (not connected to ground) power source, any +12V to +5V design will work. Just ground the +5V output and use the return lead as a -5V output.

    Regards,
    Ron M.

     

  • 0
    TI__Guru**** 191445 points

    For negative input and output using the TPS5430, the -12 V will act as the ground and system ground will be Vin.  The output voltage will be realtive to -12 V, so you would program teh output for 7 V, to achieve -5 V at teh output.  The drawback is that you are referenced to -12 V.  So any change in the -12V regulation will directly affect, the -5 V (if -12 V goes to -11 V, then -5 V will become - 4 V etc).  Also any ripple present on 12V will be on the -5 return.  In general these designs perform poorly and I do not recommend them.