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Forum Index : Electronics : nano to totem pole Mosfet drivers

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wiseguy

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Joined: 21/06/2018
Location: Australia
Posts: 1216
Posted: 04:26pm 30 Apr 2019
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I reckon it was at Digikey they were around ~ 80c each. Its best to consolidate orders to ~ $50 somewhere around there postage becomes free.

But more importantly all the stuff from Ali has a brand name something like HJBLN. At least you are getting the right genuine bits from digikey - I am very wary about this fly by night unnamed brand stuff they can write anything on the case but whats really inside? Who has the ability to measure the parameters to find out why it doesnt work as expected ?
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
BenandAmber
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Joined: 16/02/2019
Location: United States
Posts: 961
Posted: 03:02pm 02 May 2019
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Since a lot of you guys are switching over to the Nano maybe somebody has a extra 80 10 control board they would like to sell

I have desperately wanted one of them quite a while now it doesn't matter to me if it's working or not working

If I can get my hands on one of them maybe I could get a little bit more familiar with it and gain some confidence and wisdom from it

be warned i am good parrot but Dumber than a box of rocks
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 09:49pm 02 May 2019
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There is no reason in this day and age to use bipolar transistors for high power high speed switching.
If you need a fast high power gate driver, use a complimentary pair of mosfets.

Either those already there in a 4452 chip, or use a pair of discrete mosfets in a gate driver circuit of your own design.
Cheers,  Tony.
 
tinyt
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Joined: 12/11/2017
Location: United States
Posts: 441
Posted: 10:11pm 02 May 2019
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I have used UCC27322 but not in an inverter application.
 
wiseguy

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Joined: 21/06/2018
Location: Australia
Posts: 1216
Posted: 08:59am 03 May 2019
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  Warpspeed said   There is no reason in this day and age to use bipolar transistors for high power high speed switching.
If you need a fast high power gate driver, use a complimentary pair of mosfets.


All the good complementary Mosfet gate drivers I have seen usually use 4 Mosfets to avoid shoot through current issues of the complementary drivers. If you have any FET alternative circuits with low parts count and 10 Amp+ drive, please post them. I have shiploads of FETs as I prefer them for almost everything - I will have to buy the transistors for my Totem style buffers.

I believe using bipolars has afforded some advantages though in my proposed design, when powering up, any gate charge introduced from Drain coupling (Cdg) is clamped to ground (or within 0.6V) by the PNP transistor. Please note also real-estate is scarce on my PCB

Due to wanting to switch the FETs fast, holding a gate at or near ground does not ensure that shoot through cannot occur, again due to Cdg Rg and fast positive going Drain transitions. Holding the gate at -5V (or -12V) from a negative supply gives a lot more immunity from Cdg issues. Whilst a TC4452 allows a negative bias (with extra bits) it does not clamp the gate low in the absence of power or during power up.

The relatively fast discrete transistor buffers I have added to a 3A Opto/Mosfet gate driver I believe was a reasonable cost effective approach with some other advantages thrown in. Whilst the negative bias might be over kill, you almost get it for free and I consider its worth experimenting with, and you can always put in a link to disable it.

PS : some state of the art FET drivers (such as the UCC27322 TinyT mentioned) do use a hybrid of FET and Bipolar devices in the output stage.

Edited by wiseguy 2019-05-04
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike
 
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