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Dual-rail (positive/negative) linear regulator with tracking

Victor Levandovsky
Intellectual 575 points
Other Parts Discussed in Thread: OPA188, TLE2141

Helo,

I need some information about design for Dual-rail (positive/negative) linear regulator with tracking.

I`ll use TI TPS7A4701 and TPS7A3301.

I read article written by Scott Lester (Application Engineer, Texas Instruments)

http://www.eetimes.com/document.asp?doc_id=1278463

Could you advice me about pros. and cons for such approach, please?

I would be grateful for any information (reference schematics, app. notes, book references, etc. ) how design tracking circuit for  TPS7A4701 and TPS7A3301?

Also I can`t understand why Scott use non-inverting amp (G=2) I think simple voltage follower can be used.

What OPAM can be used for voltage tracking? I think I need precise low-drift like OPA188.

-- With best wishes,

Victor

  • TI__Genius 13485 points

    Hi Victor,

    The pitfall of this solution is the number of components necessary, unfortunately, I am unaware of any solution that has a significantly lower component count.  I will ask my colleagues tomorrow if they have any other solutions.  Out of curiosity, do you need closed-loop tracking, as in the output voltages are forced to track regardless of their state, or is open-loop tracking OK, where the voltages are simply synchronized together with identical ramp rates?  Also, how accurate does the tracking solution need to be?

    I believe Scott needed to limit the bandwidth of the amplifier, which would be difficult to do in a voltage follower configuration.  

    The OPA188 would work well, but it you could get away with a more general purpose op-amp, depending on your accuracy requirements.  The resistor tolerances alone will give a much higher variation than the 1-2 mV offset from a general purpose amplifier such as the TLE2141.

    Let me know your requirements for this-

    Thanks,

    Mike

  • in reply to Michael Hartshorne
    Intellectual 575 points

    Hi Mike

    Thank you for the answer and your time.

    I need (prefer) solution described in Scott`s paper (closed loop).

    I think number of components can be reduced.

    For example R1, D1, D3 can be replaced with single TVS.

    Really I haven`t any requirements from customer (I design carrier for generic PMC card and power circuit only part of  project),

    So I need best available performance from circuit, probably will use matched resistors arrays

    with 0.05%. I think I`ll use SO8 package for OPAM and OPAM can be changed\replaced during prototyping/test.

    -- Best Regards,

    Victor