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Low Noise LDO pos./neg. Pair, SOT23 or D(D)PAK prefered

Martin Liese
Prodigy 90 points

Hello,

after playing around with the LDO parametric search for several minutes I'm a little frustrated. For an analog design prototype I'm looking for a pair of pos/.neg. LDOs with an adequate performance to get the 16Bit out of the DAC at 4.096V. Preferable in an SOT23 or D(D)PAK style, so that hand soldering of the parts becoming not unnecessary painful. The MSOP8 is really challenging to handle! But either I can't find an appropriate part, meeting all the specs:

5-15V Vin
1.8-10V Vout
0.05-0.2A Iout

or I can only find a positive OR negative Regulator, like TPS7A3301. Where is the TPS7A4801 gone? Hopefully there is someone out here, who can provide a helpful hand to find a pair of LDOs for this job.

Best Regards

Martin Liese

  • 0
    TI__Mastermind 40100 points

    Hi Martin,

    The TPS7A4700 is the TPS7A3301's companion part for positive/negative rail applications. Unfortunately, it comes in a QFN package so hand soldering will be difficult to do. Purhaps you can order an EVM and somehow incorporate it in your PCB?

    Regards,

    Darwin

  • 0 in reply to Darwin Fernandez
    Prodigy 90 points

    Hi Darwin,

    thanks for your suggestions. But a QFN package is something I currently not feel comfortable with. The TPS7A33XX are also available in an TO-220. For further designs I look for an "one fits all" solution. For lower power (about 100-150mA) SOT23 or similar would be fine and for higher power (about 1A) I think D(D)PAK is a good choice. Both can soldered manually without risk. The output voltage range stays in 80% of the applications within +/-1.8-5V. To keep stock handling simple an adjustable Version would be preferred. Any suggestions? At least, do you know something about the TPS7A4801?

    Best Regards

    Martin

  • 0 in reply to Martin Liese
    Prodigy 90 points

    Hi Darwin,

    maybe the TPS7A45XX a good point to start. Unfortunately I can not find a companion for the negative supply rail.

    Best Regards

    Martin

  • 0 in reply to Martin Liese
    Prodigy 120 points

    Hi Martin, may I kindly ask how you solved this problem? I have a similar one, since a need a positive and negative rail supply regulated at 10V 200mA with low noise, like for the TPSA33 (negative) but I can't find a positive regulator in DDpack or SOT23 package (I'm not skilled in hand soldering). TPS7A4901 (positive) and TPS7A3001 (negative) are at limit like maximum current, but I can't solder MSOP-8, nor the QFN-20 (TPS7A4700)!

    Thanks in advance,

    Tino

  • 0 in reply to Agostino Manzato
    TI__Guru 55940 points

    Hi Tino,

    As you have found, a lot of our parts will include a thermal pad which seems to be what you are trying to avoid.  There are a few possibilities to still use parts such as TPS7A4700.

    1. Like Darwin mentioned, you may be able use an EVM in your design
    2. If you do a web search on "hand soldering qfn" or similar, you will find a wealth of information, videos, tips etc that can help you learn to solder such packages.
    Very Respectfully,
    Ryan
  • 0 in reply to Agostino Manzato
    Prodigy 90 points

    Hi Tino,

    this problem triggered my customer to buy a reflow soldering system. But you maybe not in such a lucky position. In my opinion for hand soldering, especially when maximum power dissipation is requiered, the MSOP8 is a no go. The QFN-20 maybe an option. You can supply an extra heatsink. We placed in this situation a larger via underneath the thermal pad, large enough that you can solder the pad to the via usind as small tip. Alternatively you can carefully apply some thermal conductive paste between thermal pad and pcb. 

    A better solution would be to put the chip or better the complete powersupply on a small separat PCB for reflow soldering or to use an eval board. In the first case you need to find someone who will do the reflow for you. But I think this should be possible.

    Unfortunately my market research in march don't show any ULN power supply chips with coparable performance in SOT23 or DDPACK packages.

    Best Regards

    Martin Liese

  • 0 in reply to Martin Liese
    Prodigy 120 points

    Thanks to both of you! Unfortunately, I really can't try to use the TPS7A4700 at this stage because I'm not yet building a PCB and really needs "through-hole" devices. That is why I'm starting to look for products of other brands, like the http://www.linear.com/product/LT1965, that seems a good candidate and it is available in TO-220

    BTW, I really can't understand why the negative regulator TPS7A3301 exists in TO-220 and the positive counterpart TSP7A4700 no...

    Thanks again!

    Tino