Re: [TCML] Driving a flyback off of mains gate drive woes.

[<lightningfor@xxxxxxxxxxxxxxxxxxxxxx>]

Download the data sheet for a IXDD414.
It is an 8 pin IC chip designed for driving mosfets and IGBT.
High power output and I am pretty sure it can be triggered by 5v logic.
Check it out...

Carlos

On Thu, 06 Oct 2011 22:26:47 -0400, Scott Bogard <sdbogard@xxxxxxxxx>
wrote:
> Hi Dave,
>       Yeah I saw that schematic, it kind of gave me the idea, switchable

> from 120 to 240 volt operation, super high power capacity, but there are

> limitations with that chip I'd like to circumvent.  Namely that it is 
> stuck on 50% duty cycle (overall flyback duty cycle is independently 
> controlled by a second oscillator at a low frequency) and that you have 
> to use the built in frequency generator (I have a frequency generator, 
> that I can program frequency routines into.)  Basically I need some kind

> of plane Jane MOSFET driver that I can mount to the high voltage rails 
> like that chip, but that accepts an external input 5V logic, I don't 
> think such a thing exists, so there must be some way to build one...  
> Can I make a BJT totem (I think that is what it is called) fed by like a

> 3k resistor or will that pop under that voltage?  Thanks in advance for 
> your help guys, it is so much appreciated by this solid state newbie!
> 
> Scott Bogard.
> 
> On 10/6/2011 8:20 PM, David Speck wrote:
>> Scott,
>>
>> Below is a link to a full schematic for a flyback driver off the 
>> Information Unlimited website.  No personal experience to know how 
>> well it works, but it seems to be a close match to the sort of thing 
>> you are looking for.
>>
>> http://www.amazing1.com/download/PVM500BASICSCHEMATIC.pdf
>>
>> Dave
>>
>> On 10/6/2011 6:40 PM, Scott Bogard wrote:
>>> Greetings all,
>>>      Back up to my old tricks again.  After procuring a schematic for 
>>> a PVM 400 flyback driver, and noticing it runs off of mains voltages, 
>>> I am attempting to create my own version, with programmable 
>>> adjustable duty cycle and frequency.  What I don't seem to know how 
>>> to do, is drive the gates, what I have is an ATmega chip producing a 
>>> nice 5 volt square wave, of variable duty cycle and frequency (3-300 
>>> kHz) and some good flybacks.  Obviously I cannot just plug that 5 
>>> volt signal into a bunch of MOSFET gates, it would likely not have 
>>> the guts to hold them open, even if it was the correct ground, which 
>>> it is not.  So basically what hardware is needed, a gate drive 
>>> transformer?  MOSFET driver?  Could somebody please point me to some 
>>> straightforward literature about biasing MOSFETS, and possibly 
>>> provide part numbers, not just reference "generic BJT."  I know it 
>>> must be possible, people have run solid state TCs off of MOSFETs for 
>>> a long time, so what am I missing...  Thanks in advance, I'm looking 
>>> specifically to run it off of about 320V DC (+-160V) low side drive 
>>> (not half or full bridge) if that makes a difference.
>>>
>>> Scott Bogard.
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