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Recent content by doors666

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    using both Spice and IBIS models in a design

    Spice and IBIS I am trying to simulate a circuit in ltspice. Most of the circuit is done, but i cant find the spice models for a couple of components. I found IBIS 3.2 and hspice models for these, but I could not convert these to spice models. I tried a few softwares like the orcad 16.6 demo...
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    merging pwm and analog signal

    Lets say system is designed for max 5A. The user should be able to configure it like this - Run the system at 2A, with 10% duty cycle at 10khz. Microcontroller's dac will give me a voltage representing the 2A on a 5A scale. UC will also give me the pwm signal. Now the mosfet should drive the...
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    merging pwm and analog signal

    How do I feed this signal to a mosfet? My switching speed can be as much as 1mhz and I dont have enough current in this signal for fast switching. I looked at quite a few mosfet driver chips, but most of them are suitable for dc-dc converters or for h-bridges. I found a few simple ones but those...
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    merging pwm and analog signal

    Basically I want to control a mosfet with this signal. I want the analog signal to control the current level and pwm for controlling the switching at the same time. Current capability might not be there so i will need to use a mosfet driver or something like that.
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    merging pwm and analog signal

    I guess an image will clarify what i want.
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    merging pwm and analog signal

    i have another question related to PWM so I guess i will add it here. How do I calculate the power requirements for components while using PWM. e.g. if I use a 1 ohm current sense resistor for 5A current, I need a resistor of 25w + some margin. How much wattage resistor do I need if I am going...
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    merging pwm and analog signal

    I have a analog dc signal for which the voltage varies from 0-1.23v. I also have a 3.3v pwm signal, for which the worst case frequency will be 1mhz. I need to merge these two so that the output signal is switched as per the pwm but the voltage level is as per the analog signal, kinda like a...
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    high offset voltage in 741 voltage follower.

    I want to try the first circuit in the link you posted above. I have 0.5 ohm 5w and 1 ohm 2w for the current sense resistor. lm317 is on a decent sized heatsink. Is 1k a good value for the base resistor r2. I currently dont have a pnp bjt, I should be able to use a p channel mosfet instead...
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    high offset voltage in 741 voltage follower.

    I also have a simple lm317 based supply that had a minimum starting point of 1.2V, which is as per the datasheet. I tried the circuit mentioned at the link below to get down to 0v. It doesnt seem to work for me. I used a tip31c as the transistor. I am using a 12v dc supply for input instead of...
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    high offset voltage in 741 voltage follower.

    thanx for the help guys, i tried with a -ve rail and it works fine, I get an offset of 44mv, which is ok. I will try to answer all the questions here. What is the highest frequency of your signal? Right now I am just trying to test the concept, but eventually it will go to about 1mhz, square...
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    high offset voltage in 741 voltage follower.

    i was trying to do a simple voltage follower but I am seeing a very high offset voltage, about 1.8-2v. I am using a 12v-gnd supply. I used a 10k feedback resistor and grounded the non-inverting end. Even when i apply a signal to +ve terminal that varies from say 0-5v, I get steady 2v output...
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    What are some cheap connectors that can handle about 25A current?

    The molex connectors are rated for 12v only. I need to handle upto 30v. Not sure which faston connectors you are referring to, there are quite a few different types of them google throws up.
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    What are some cheap connectors that can handle about 25A current?

    I need to carry about 25A current from the psu pcb to another pcb. Distance will be about 6 inches. Max voltage will be about 30v. Any suggestions. Its better if the size is not too big. I would prefer to have a m/f connectors with wires rather than the wires being screwed straight into a terminal.
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    Voltage Regulators in-depth

    can the 78 series of voltage regulators provide higher current than rated for switched applications depending upon the duty cycle?
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    regulating smps output at a lower voltage

    chip i am using wants max input of 22v, so the 21v need. i dont need exact value, but it shouldnt drop too much. about 20v min. I guess that isnt exactly regulated. I would probably need about 25 amps capability to use 20a from the smps. cost is of course an issue, dont want it to be...

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