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SCRs in an IC? — Parallax Forums

SCRs in an IC?

ercoerco Posts: 20,259
edited 2011-12-06 10:06 in General Discussion
Is there an existing DIP IC that has multiple SCRs inside? Seems like a natural, but I haven't found one yet. 800 mA is typical for TO-92SCRs, seems doable in DIP format.

Comments

  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2011-12-05 15:21
    ... other than the parasitic ones we try to avoid? ... I haven't seen any intentional integrated SCR's ... they are always a separate discrete component(s).

    http://forums.parallax.com/attachment.php?attachmentid=68057&d=1267024100
  • ercoerco Posts: 20,259
    edited 2011-12-05 15:25
    Beau Schwabe (Parallax) wrote: »
    ... other than the parasitic ones we try to avoid?

    As I always say, "If you can't fix it, feature it!" :)
  • jrjr.jrjr. Posts: 45
    edited 2011-12-05 15:38
    Beau,

    That was the first thing that came to mind, start up FETS.

    jr
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-12-05 18:29
    You could use non-inverting buffers with feedback resistors and diodes feeding the inputs. I'm not sure how they would power up though. 'May have to add small caps from the inputs to ground to force an "off" condition on power-up.

    -Phil
  • Tracy AllenTracy Allen Posts: 6,666
    edited 2011-12-06 00:34
    Some thyristor arrays exist specifically for circuit protection. For example, the Littlefuse SP720 has 14 thyristor clamps in one 16-pin package, the idea being to shunt fault currents rapidly away from sensitive ic inputs and to avoid stressing the substrate diodes and bond wires.

    The old CA3097 array had a smorgasboard of independent parts in a 16 pin DIP: An SCR, a PUT (programmable unijunction transistor), a Szilaki high gain pair, a zener diode, and a standard NPN. It could be done. What I have been looking for is a PUT in an SOT package. They don't seem to have made the transition to surface mount at all, still only available in TO92.
  • ercoerco Posts: 20,259
    edited 2011-12-06 09:06
    Great info on that 3097, Tracy! There are 10 available on Ebay for $10.70 each shipped: http://www.ebay.com/itm/RCA-CA3097E-Thyristor-Transistor-Array-Very-Rare-Device-Nice-Experimenter-IC-/290634180301?pt=LH_DefaultDomain_0&hash=item43ab25a6cd

    From a US seller, who confirms they are rare NOS parts. Just the stocking stuffer for your collector of vintage ICs!
  • Tracy AllenTracy Allen Posts: 6,666
    edited 2011-12-06 10:06
    Wow! I have 5 of those in my parts drawer on antistat foam and I'm sure I paid about 2 bits each for them. It is a peculiar array and I wonder what led RCA to produce it. The applications in the data sheet have to do with power supplies, timers and dimmer controls.

    Erco, if you run across PUTs available in a surface mount package (singles), let me know!
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