34063 circuit irfz44
sorry,reread my post, it doesn't explain it too well.
standard step-up boost circuit for this 34063
the switch element being a mosfet.
See, if you short the output, the current flows thru the Rsc the coil and the diode, which then proceeds to release smoke.
Because the switch device is not in series, the current limit feature of the controller has no effect.
The circuit otherwise runs well and efficient.
So I proposed to change the coil to a transformer, so its a feed-forward design.
and this i'm having trouble with.
As a reference I'm looking at a design in "Motorola Power Mosfet Transistor Data" book,figure 8-9 showing a automotive dc-dc 9-24V=>54V, only it uses a MC34060. claims 78% efficient.
I've been doing some more research, whats a reset winding? I think i know now, but not sure how to wind one, or number of turns etc.
but that reference design I just mentioned doesn't use one and its 78% efficient??
I did notice when in one configuration of wiring up the 2 secondaries I wound, and I was monitoring the drain on the switching mosfet, and there was like 60V peaks occurring.......60V thats the breakdown voltage of the mosfet IRFZ44 !!
and it was getting HOT.
I don't think! its damaged....its all running from a current limited PSU atm. But when it runs from a battery, potential of smoke release is very very much greater.
here is a pic of the secondary windings,
not too neat is it? should it make much difference ?
How important is it in how carefully it is wound?? You'll notice the core is glued to the PCB, so winding it was a bit of a pain.
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