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Everything posted by AbhimanyuSingh

  1. While trying to place the componets manually in Orcad Layout, when I select a component, there comes a whole load of texts and arrows free with the package. That messes up the whole layout diagram and I need to delete each arrow and text manually. This becomes very tedious. Is there a way to avoid these texts and arrows while selecting and placing the components.
  2. This is my first day on PCB design and am working on Cadence orcad version 16.5. I created netlist. .mnl file is created. But i dont see .tch or .brd ...So i tried to create netlist, and in the PCB editor tab, i did some changes. That gave a long list of errors. All saying the same, "PCB Footprint" missing frok instance XYZ. What does it mean. What to do next.
  3. Can someone pls help me with Average current control modeling. The block diagram of the circuit is attached. But I dont know the basics of this technique. How can I calculate the values of the resistors, capacitors, the constant in multiplications etc. How to derive the transfer function of each block. Every book or any other material narrates the same outline story of how it works. But they are not helpful.
  4. Can someone suggest me any literature or book or any material where I can read and understand the very basics of average current mode control for a boost converter. By basic, I mean the purpose of every block, component, every theoretical detail. I need it urgently.
  5. This gate driver is for a buck converter. The input to this IC is a nice pulse of frequency 100 KHz of variable duty ratio. I have checked the circuit many times and ensured that no shorting is there. But the output remains 0 volts. The output HO is hanging as well as the output VO is hanging. For the sake of step by step progress, I have left them hanging. Is there something I have missed or something I dont know that I should have done.
  6. While using SG3524, for buck converter, I need to give a feedback to the error amplifier at pin 1. At the output of the error amplifier (pin 9) I have the Caps and Resistors for compensation. Do the capacitors here need to be ceramic disc capacitors necessarily? Or any specific type of capacitors?? Cannot I use Electrolytic aluminium capacitors? The problem arises because I got ceramic bead capacitors of value only 0.1 microfarad, whereas I need a capacitor of very high value there (I might be wrong).
  7. Thank you for your reply and for your concern. There is no load, which I thought would be inappropriate at first. The value of the inductor is 0.150 mH. Ramp voltage, as in normal situation is there on pin 7. Pin 12 and 13 are shorted and there is signal with almost 0 duty ratio on pin12 and 13 shorted.
  8. This is one of the test circuits given in datasheet of SG3524, with a little modification, mostly insignificant, like changing the value of inductor and using just one BJT instead of 2, as given in datasheet. I am not getting any output there. The expected % volts is not there. The signal out of pin 13 has a duty ratio of almost 0. What could the reason be. What possible mistake have I made. Even if I change the voltage at pin 2 (off course remove this voltage divider and put a rheostat), I dont find any change in duty ratio. Also once it happened, in another occasion that I was getting 2 volts at that point once I switched on the circuit and that voltage remained there even after i switched off the power supply. What could be a reason for this. The circuit is built on a bread-board. So its a little lousy, but there were no loose-wires. I am posting the circuit diagrams. The first file is the circuit i have built and the second file is the test circuit given in datasheet of Texas Instruments.
  9. Thanks Hero999.. It was this bootstrap problem and I dealt with it. Yeah I know I dont have to manually adjust the duty cycle, but at initial stage I used to adjust the positive input of comparator of SG3524 manually. I get good duty cycle from both SG3524 and IR2117. But there is a new prob now. I have to connect a PI controller in my circuit to keep the output voltage equal to 5 volts. I have passed the output (of the buck converter, which is supposed to be 5 Volts, after scaling it down) to the positive output of the comparator of SG3524. The negative input of comparator is output of PI controller and PI controller's input is the output of comparator. I know this sounds confusing. If you ppl need the schematic, I will upload it next time. I have used LM324N for PI controller. The prob that I see is, "P" controller works alone fine. "I" controller works alone fine. I.e. if they are broken in to parts and connect them , they individually work fine. But when I short the input and output of "P" and "I" controller, the output no more remains as expected. Why dont the "P" and "I" work together properly? Also when I use "P" and "I", I use the same IC for both. Thanks in advance.
  10. I have to build a buck converter, with variable input from 10 V - !5 V. Use a PI controller to maintain the output at 5 V. I have used SG3524. Now, it is clear that I should be able to attain a pulse width of duty ratio 33% to 50%, exactly speaking. And wider range of duty ratio will be even better. Also I am getting duty ratio of 20% to 70% from SG3524. But the problem comes after that. The output of gate driver IR2117 which is supposed to follow its input, does not follow it for a pulse of duty ratio more than 30%. Why is it so? If i decrease the duty ratio below 30 % the output of IR2117 follows input, but not for more than 30%. There is nothing mentioned so on the datasheet. The frequency i m using is 100 khz. is there any other option for me, like change the gate driver. Can anyone suggest me a gate driver which wont be having this problem. Or else can anyone tell why is this happening. Ask if have missed some information to provide.
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