I had some trouble identifying what the current draw of the components I am using... Looking on the datasheets for the following components - LM324, IR2183 and TL494 it was not obvious which value should be taken..
For the LM324 there are several values listed for current. Should I use the supply current which says only 1.5mA or take the value from the output current which on the datasheet says 40mA source. Looking at maximum power disipation it says 1130mW for the DIP package so if I am using this with say 15 volts that 75mA.
For the IR2183 this appears to deiliver a large but very narrow spike to the gate of the mosfet.. however it says "Output high short circuit current" - Typical - 2.3 amps.
For the TL494 it says the recommended current for each transistor is 200mA.. so should this be say 400mA as there are two outputs...
If I assume that I only require the 2.3 amps to charge the Mosfet capacitor which would be 150nC / 2.3A = 65.2ns where the 150nC is the required gate capacitance of the IRFP450 - that is ~170th of a Hz cycle so an average of ~13mA over the course of a full cycle then...
I need a pretty small power supply for this... 75mA + 200mA + 13mA so around 300mA minimum and thats at 15 volts I am assuming so a transformer that transforms this down to 15 Volts would be Vs/Vp=Ip/Is so 15/240 * 0.3A =18mA so a transformer of say P=V* I => 240 *18mA = 4.5VA....
When I run an average on the current for the component IR2183 - Ix(U2:1) in Spice it comes to around 5.7mA.
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Am I in the ball park on this or have I made some obvious wrong assumptions re the datasheets and the calculations...
Kind regards
Simon