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    6v to 12v inverter

    Just about all DC-DC's have a input range... for example our 5V input models have a range of 4.5V to 9V. 12V models work from 9V to 18V, 24V models work from 18v to 36V and 48V models work from 36V to 75V. That's the nice thing about them...
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    OVER-/UNDER-VOLTAGE PROTECTION CIRCUIT ANALYSIS

    I was taking about the difference between opamps and comparators in general, not specficic part numbers. What I said was Are you suggesting that a opamp can't be compensated such that it's "fast"?
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    OVER-/UNDER-VOLTAGE PROTECTION CIRCUIT ANALYSIS

    There a bit more difference between the two than just that... Can compensation make a opamp switch slow??? Yes it can, but  it's not automatic, you you have to select a value (LARGE) on purpose for that to happen. Then, slow is a relative term, how slow is slow? One reason why opamps make lousy...
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    opamps

    Just apply the following to get the "general idea" of how they work 1) the inputs to the opamp have infinte impedance... this means no current will flow into of out of an input. 2) the output has zero impedance... this basically means it could supply infinte current 3) the output will do...
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    Voltage-to-pulse-duration converter

    Yes... we (where I work) have a flyback DC-DC converter (voltage mode) design that uses a 556. It's configured like Fig 6 in that app's note and the feedback is fed into the control pin. The only problem is that the frequency isn't constant. We use the other half of the 556 as a one-shot for the...
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    Help me choose a mosfet

    Take a look here http://www.vishay.com/mosfets/lteq-20-v/micro-foot-package/ Note the Rds on with a Vgs of only 1.5V!! Even at 2.5V they are all below .05 ohms In general, you'll find that N channel MOSFET's have lower Rds on numbers than P channel.
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    transformer getting too hot.

    Yes... but there is no "C" here. It's a series RL circuit. You short windings of a transformer to measure leakage inductance, but the transformer isn't active. To measure the leakage inductance of a winding, short ALL other windings and measure the L of the winding of interest on a bridge at...
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    transformer getting too hot.

    You were doing what?? You can't connect a wire across a transformer winding... that is a short. Yes, a transformer will get hot if you short it's winding. Tell us a bit more about... Resonance with what? Self resonance? How are you changing the frequency? At best wire "looks like" a series...
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    6v to 12v inverter

    Yes... DC-DC converters will do what you want. The power range your looking at is NO PROBLEM!!
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    power sequence question

    The motherboard. There are electronics someplace that control the "power-up" sequence and type. Are you trying to margin test the voltage, or the sequence time?
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    power sequence question

    It's not the sequence of the power supplies themselves that is important, but it could be VERY important to what they are "powering-up". For example, some CPU's are very particular in what order it see's which voltage.
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    how to convert 3-24Vdc to 12vdc

    The DC source does not matter... whether it's a battery or rectified AC.
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    how to convert 3-24Vdc to 12vdc

    You could use something called a buck-boost converter.
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    Inductor in LC filter

    Frequency does matter. In a power application for example... take a simple buck converter, Vout/Vin will tell you the ~ duty cycle, but the frequency will determine the "off time" (flywheel period during which current is flowing out of the inductor) of the converter. That "off time" plays a...
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    SG3524 buck converter

    In your schematic you show pins 12 & 13 connected to the drain of the the IFR 540. This is a switching node (the voltage goes up and down and you don't want that). They (pins 12 & 13) should be connected to either Vin or the Vref pin and you need a pull down resistor on the driver input...
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    5 volt to 3.3 volt

    John, John, John
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    SG3524 buck converter

    In "your" circuit, you have pins 12 & 13 tied to the drain of the MOSFET... I think they should be tied to either Vref or to Vin unless in your final design the Vin voltage will be to high for MOSTFET driver. While you could use this voltage mode control PWM (SG3524), it's considered "old"...
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    5 volt to 3.3 volt

    Audioguru First you said Then you brought "dynamic impedance " into the picture for some reason (NEVER applied to this circuit) and now your saying... If the zener isn't regulating anything, then what is controlling the output voltage??? Whether the load is changing or not in this circuit is...
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    5 volt to 3.3 volt

    Audioguru While you didn't exactly answer the question directly, your reply kinda has the answer if you "read between the lines".  OK, now let gets back to why you think  "dynamic impedance " comes into play in this particular circuit, as in your reply, you basically stated that the circuit...
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    smps modification

    ou could use a buck converter. Limiting the current for the 5V @ 1-2A could be an issue if you can't live with a fuse.
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