3
votes
Accepted
Designing DC-DC buck converter based on the L6981 (L6981C50DR)
Vin=12V, Vout=5V so duty cycle D=0.42.
F=400kHz, so T=2.5µs.
Ton = T.D =1.04µs
During Ton, L has (Vin-Vout) across it, so the inductor current ripple \$ \Delta I = \frac{Vin-Vout}{L} T_{on} \$ = 220mA....
- 81.6k
2
votes
EMI filter design for a DC-DC converter
Your EMI will be highly related to your layout, so start with that first and make provisions for filters on input and output side.
If you add parasitics to your schematic, you will be able to simulate ...
- 16.8k
2
votes
Accepted
How to deal with low values of coupling coefficient in resonant circuits?
You can use the realistic coupling k=0.1 and lower the Q by loading the output with a load. To match the Q of the original sweep. By transformer source R by N^2 turns ratio one can estimate the load ...
- 148k
2
votes
How this circuit works? inductor amplifier
C3 and C7 are to remove DC content but there shouldn't be any. I would eliminate these two caps since they serve no purpose and are polarized for no good reason. The gain of each amplifier is 390 ...
- 21
1
vote
Choke and MOSFET temperature relationship in VRM system
The inductors have copper I2R losses, and core losses proportional (not linearly) to flux density and frequency.
The FETs have I2R and switching losses. But the conduction losses are distributed ...
- 24.7k
1
vote
MOSFET driving external inductive load with high-side PTC protection and free wheeling diode
If the PTC opens, the free wheeling diode effectively looses its
benefits temporarily
That is untrue. If the diode is across the terminals of J8 it is also across the inductive load and, when the ...
- 473k
1
vote
How to find mean length per turn (MLT) for magnetic design from ferrite cores datasheet?
Conventional low frequency transformers with a square or rectangular core and no waste laminations. I put the measurements of say Miles Platts bobbins into a database including the wdg width for 1 ...
- 11
1
vote
Not getting spark from ignition coil test circuit
The polarity of your battery is wrong and a typical good old ignition coil needs a capacitor of around 200 nF / 250 V across the switch for a powerful spark.
The secondary winding together with the ...
- 8,335
1
vote
Not getting spark from ignition coil test circuit
2.5V at the gate is probably not enough to make the MOSFET conduct well enough to generate a spark.
From what I find, it takes 4 milliseconds or more to "charge" a spark plug coil. You need ...
- 73.5k
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