There are hundreds of DC to DC converter, you can use a DC to DC converter IC or DC to DC converter Modules . Try DC to DC converter datasheet
There are apparently more errors in the present circuit. I e.g. can't detect a path to turn on the output transistor. You may want to show the original circuit source to make us understand what happened to it.Yes, I missed out a connection from C1 & C2 to the collector of Q3 in the schematic.
I don't have much time to study the theory of TL494 driven power supply but at a quick glance it seems that the 0.1 ohm resistors are reading the current for overload protection. Put three additional resistors in parallel and this must solve your problem. This is just a guess so please don't blame me if you burn something.
Hello mdorian,
I put 4x0.1R now the circuit work very well with 3A load. Thanks!
There are apparently more errors in the present circuit. I e.g. can't detect a path to turn on the output transistor. You may want to show the original circuit source to make us understand what happened to it.
When up-scaling the circuit to 5A, current and power rating of output transistor and diode, inductor current rating, current sense resistors, as already discussed, are affected.
P.S.: BYV32 and IRF9530 are basically suited for 5A output current, but you have to provide sufficient heatsinks for both devices. I think, that a schottky diode would be better, due to both, lower forward voltage and reverse recovery losses.
Yes, you mentioned this before. But I don't understand how the FET can be driven using exactly this circuit. However, if it's working, you don't need to worryThe original circuit I posted in my 1st post which I missed out a connection from C1 & C2 of TL494 to the collector of Q3.
Take FvM's cautions to prevent overheating and you can try 7X0.1R to raise the overload protection limit to 5A
Hm. I also noticed, that the transitor losses aren't optimal yet, so it may be advisable to check the gate voltage waveform and possibly take a closer look at the driver circuit.I also don't understand. But it works.
charge pump is a good choice
Some losses are normal operation. I suggest to determine the efficiency, by measuring input and output voltage and current, and decide if it's acceptable.But the FET & Schottky Diode is hot, I only can touch the heat sink with my finger for only 1sec.
The gate drive circuit still doesn't look reaonable to me.The circuit has some error on the transistor side in my previous schematic.
As I mentioned above my input & out are "input 27V(not 24V) ->2.6A, 12.7V ->5A.(drops to 11.6V actually)."Some losses are normal operation. I suggest to determine the efficiency, by measuring input and output voltage and current, and decide if it's acceptable.
So the efficiency calculates to 82.6%. Not mind-blowing, but acceptable. A National Simple Switcher IC (LM2679) is said however to achieve about 92% at similar conditions.my input & out are "input 27V(not 24V) ->2.6A, 12.7V ->5A.(drops to 11.6V actually)
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