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THS3202: THS3202

David Lake
Intellectual 300 points

Part Number: THS3202
Other Parts Discussed in Thread: THS3201, OPA2695, OPA2694

I got 2 THS3202 from Farnell to satisfy my own personal curiosity and after soldering one perfectly to a DIP adapter to use in a breadboard I turn on the linear bench supply at 12v limited to 20mA and it appears to be shorted internally to some extent and drawing 20mA at about 4.8v

So I try the second one without touching it by hand and put it in a spring loaded SOIC to DIP adapter, stick it into a different location on the breadboard and connect just the supply and it does exactly the same thing, it draws 20mA at about 4.8v.

I checked over everything several times, its the right way round, I have no idea what's wrong as they are both doing exactly the same thing.

  • 0
    TI__Genius 15605 points

    Hello David,

    A 2GHz part like the THS3202 is very sensitive to parasitics, the parts you tested are likely oscillating. In the layout portion of the datasheet, it mentions that even using sockets isn't recommended and so the part will definitely not function properly on a breadboard.

    Best,

    Hasan Babiker

  • 0 in reply to Hasan Babiker31
    Intellectual 300 points

    The problem may be that there is no warning of any kind that the output should not be directly connected to the inverting input for a traditional buffer configuration as there is virtually no output resistance and very little resistance on the inverting input so it shorts and destroys itself.

  • 0 in reply to David Lake
    TI__Genius 15605 points

    Hello David,

    This is correct, current-feedback amplifiers need a feedback resistance even when in a buffer configuration. You can find recommended resistor values in Table 1 on page 17 of the datasheet.

    Best,

    Hasan Babiker 

  • 0 in reply to David Lake
    Guru 48395 points

    Every current feedback amplifier will do that, also the THS3202 is NRND as is the THS3201. 

  • 0 in reply to Michael Steffes
    Guru 48395 points

    Hello David, 15

    So I was involved in NRND these two parts, they have some produceability issues - I know the OPA2694 is pretty close except for the 15 supply on those older parts (and the OPA2695). 

    So I tried to put the THS3202 into the parametric cross to see what else might be close parametrically - they have been removed.That is a mistake - when I have built parametric match tools we leave obsolete parts in to help folks find close replacements - important, at the time of obsolesense you can't anticipate what new parts might come out, as those are added to the tool, maybe new options will appear - but only if  the old parts are still  in the tool.