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NE555 as gate driver for IGBTs & power MOSFETs — Parallax Forums

NE555 as gate driver for IGBTs & power MOSFETs

User NameUser Name Posts: 1,451
edited 2015-04-12 20:46 in General Discussion
Logic-level gate drive hasn't permeated the field of high voltage and high power IGBTs and MOSFETs to any great degree (which I consider a good thing). The link below is one of my all-time favorite tips. Fancier and more expensive chips are available for gate drive, but in a great many instances they are not needed. Using the reset pin as input, a humble bipolar (NE or LM) 555 makes a handy, effective, and inexpensive MOSFET or IGBT driver that can interface to logic devices with VDD as low as 1.8V. Works great with a Propeller!

http://electronicdesign.com/power/lm555-makes-inexpensive-power-driver

Comments

  • tonyp12tonyp12 Posts: 1,951
    edited 2015-04-09 10:54
    With so many gate drivers out there why use a device that was not made for it.
    Though a 74ABT buffer could do the job if you need a strong 5V drive on the gate.
    http://www.mouser.com/ProductDetail/NXP-Semiconductors/74ABT126D623/?qs=sGAEpiMZZMuiiWkaIwCK2RTxPVPWGz6W%2f6l5miHIMtY%3d

    Would use a MIC4606 if I need to drive 4 mosfet in h-bridge, it got bootstrap so you can use n-msofet on the high side and also shoot through protection.
    (boot strap is a simpler version of a charge pump, where it uses the actual switching itself as the pump)
    http://www.mouser.com/Search/Refine.aspx?Keyword=MIC4606
  • kwinnkwinn Posts: 8,697
    edited 2015-04-09 11:41
    The 555 is a chip of multiple uses. As a gate driver it can be used to turn on/off devices that require up to 15V with a 3V signal.
  • davejamesdavejames Posts: 4,047
    edited 2015-04-09 11:47
    User Name wrote: »
    ...a humble bipolar (NE or LM) 555 makes a handy...

    Thanks! Saved the article.
  • tonyp12tonyp12 Posts: 1,951
    edited 2015-04-09 12:52
    1.5A gate drive at 4.5V to 18V with a min 2.4V logic
    Dual drives at 52cents (so 26 cents a driver), comes in [dual non-inverting] [dual inverting] and [non-inverting+one inverting] so it's a mix and match to your needs.
    http://www.mouser.com/ProductDetail/Micrel/MIC4427YMM/?qs=sGAEpiMZZMvQcoNRkxSQkhw4FYdqpzaL%2f2rEdibQec8%3d
  • User NameUser Name Posts: 1,451
    edited 2015-04-09 13:52
    @tonyp12:

    Yup. There are indeed a lot of fancy gate drive chips. I've even used a few. :)

    Of course a 52¢ chip starts looking more like a $15.20 chip once minimum order requirements are met and UPS freight charges are applied. So if you need a faster and more powerful driver, great. If you don't, and you already have a 555 in a drawer, you just might be able to save both dinero and delay.

    Haven't you ever used a cheap framing hammer to flatten a piece of sheet metal when a ball peen hammer wasn't at hand?
  • Mark_TMark_T Posts: 1,981
    edited 2015-04-12 17:44
    Alas that article recommends an 8 to 10 ohm gate resistor which will mean the '555 is
    stressed beyond its abs max ratings. Something more like 50 ohms is needed to keep
    the output current within safe limits (although the data sheet I've seen doesn't quote a
    peak max output rating).

    For me the MIC4422 will do the job nicely (and I have a bunch kicking around, which is
    more than can be said for the bipolar 555 - the CMOS version is better so I only have 7555's
    and they have less drive capability.
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2015-04-12 19:16
    What a great idea! There are whole books on nifty 555 circuits - this adds another chapter to the book. Good old 555.
  • lardomlardom Posts: 1,659
    edited 2015-04-12 20:46
    User Name wrote: »
    Logic-level gate drive hasn't permeated the field of high voltage and high power IGBTs and MOSFETs to any great degree (which I consider a good thing). The link below is one of my all-time favorite tips. Fancier and more expensive chips are available for gate drive, but in a great many instances they are not needed. Using the reset pin as input, a humble bipolar (NE or LM) 555 makes a handy, effective, and inexpensive MOSFET or IGBT driver that can interface to logic devices with VDD as low as 1.8V. Works great with a Propeller!

    http://electronicdesign.com/power/lm555-makes-inexpensive-power-driver

    Thanks. Bookmarked the link. I have a supply of mosfets that I wanted to use with pwm instead of transistors.
  • User NameUser Name Posts: 1,451
    edited 2015-07-07 17:00
    Alas that article recommends an 8 to 10 ohm gate resistor which will mean the '555 is

    stressed beyond its abs max ratings. Something more like 50 ohms is needed to keep

    the output current within safe limits (although the data sheet I've seen doesn't quote a

    peak max output rating).


    The physics of the output transistors limits the available current anyway, and this condition persists for a few microseconds (or less) per transition.  Entirely innocuous both in theory and practice - at least from DC to 20 kHz or so.

    BTW, it should not have to be mentioned (Tony) that this idea is not being directed at commercial SMPS manufactures. ;]  Furthermore, there is no compulsion to change what is working for you.  It's just an idea that has been convenient and successful in a wide range of circumstances - to the point that I tend to leave the dedicated gate drive ICs on the shelf and go to the 555 in most instances.
  • Heater.Heater. Posts: 21,230
    On the other hand I have seen switched mode power supply designs, boosters, that use a 555 and the recommendation has been to use some external transistors to drive the MOSFET gate to get fast switching speed and hence efficiency. Sorry I don't have a link to hand.
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