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you asked for 3A at 24V froma 12V battery. I was asking what the circuit that you posted puts out.
If you want to use less than a 10uH you need to either reduce the frequency or the rated power, of course that is assuming that it is doing doing what you want otherwise.
I only find upper schematic for example and it`s in accident near to my circuit ...
about Self:
I think high frequency provide to us low reple in output and also reduce efficiency! and i like to use bigger self in my circuit but How much uH? what is the formula ?
Sorry I did mean a larger inductance... the formulas depend a lot on how the chip runs... in general you need to get enough energy into the inductor with out saturating it to get the amount of energy you need out of the converter.
J=½I²L and I=tV/L and if memory serves W=Jf in this case (W=J/S).
You will need to add current limiting. The boost topology is not protected against a shorted output.
Regarding the inductor current rating, if the average inductor current is 9 A, then the peak will be greater. But, not 18 A if continuous conduction mode is used. The double value occurs if boundary mode is used. With a large enough inductor value, with 9A average, the peak can be 12A, while the valley can be 6A. As the L value increases, the ripple decreases, i.e. 11A peak w/ 7A valley, etc.
Since the duty factor will exceed 50%, instead of a 3845, use the 3843. It is identical in all respects except there is no toggle flip-flop which limits duty factor to 50%. I'd use the newest CMOS version, the UCC28C43 part. Have I helped?
Why don’t you use a modern controller like TPS40210 these are only about two bucks. There are lots of online tools to use here is TI’s. For your input / output.700kHz.
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Ratings for power stage components
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Just select the external components from your preferred supplier. You can get select a better mosfet Alpha & Omega Semiconductor make nice logic level ones low Qt Rdson good prices etc and pick a better Rectifier.
TPS40210 product folder, with online tool.Spice models etc.
Thanks about your remark, At end my UC3845 has been explosions and i buy another UC3843 it make for me about 21 volt and 2.8 AMP to! u think i must use TPS40210 and UC384x can`t handle my Load!?
I see the sites its perfect! thanks about that too.
AW! forget this-> IS RIGHT? : THE WATTS OF BOOST TOPOLOGY IS 150W AT MAXIMUM AND PERFECT DESIGN ?!!!!!!
I’m not saying you have to use the TPS40210, I’m saying there are better controllers out there for the same price or little difference. This one has internal slope comp, has a fraction of the current sense resistor power req etc. The reason I suggested that controller is; it is well supported with spice models the online tool and a very detailed design for a boost converter in the data sheet. The part is also widely available. Ultimately your choice will depend on what you can get. I live in North America so sourcing components for me is easy. Where you live this may not be the case.
The above was meant as an example of what’s available to assist you in your design. If you go to other semi manufacturers they usually have tools that will recommend a controller for your design parameters. You still have to apply common sense obviously you want higher voltage rated caps and some of the other components should be upgraded. I use them as a general guide,to give me a rough idea of what I'll be needing.
The controller doesn’t set the power output, the power stage components do, unless the controller has an integrated switch.
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