Hi FMs,
I have a si8244 circuit which is not working I dont see the output waveform window opening forming / not simulating. I have independently saw the PWM output which has a triangle generator which is also working as expected but the moment I have simulated the circuit I see the output is not coming. Something wrong in what I did ? Is the spice model correct.
Im attaching the following .asc file as well. Please anyone can help what is the problem of this circuit or sim? Im not able to understand as everything seems ok.
I have a si8244 circuit which is not working I dont see the output waveform window opening forming / not simulating. I have independently saw the PWM output which has a triangle generator which is also working as expected but the moment I have simulated the circuit I see the output is not coming. Something wrong in what I did ? Is the spice model correct.
Im attaching the following .asc file as well. Please anyone can help what is the problem of this circuit or sim? Im not able to understand as everything seems ok.
Attachments
You might want to check the logic polarity and see if this is an inverting or non-inverting gate driver IC, especially if you have a self-oscillating amplifier like in the app notes by International Rectifier.
Not sure these're issues but why do you have 10R between Vout and the chip ? If this is meant for current limited charging of the bootstrap capacitor then the apt place would be in series with the bootstrap diode. Also, you need the bootstrap diode only on the high-side floating capacitor and the bottom one could be direct (short D4). Often, one does not need snubbers or the extra freewheeling diodes during simulation, as the parasitic inductances are often not included in SPICE models.
Not sure these're issues but why do you have 10R between Vout and the chip ? If this is meant for current limited charging of the bootstrap capacitor then the apt place would be in series with the bootstrap diode. Also, you need the bootstrap diode only on the high-side floating capacitor and the bottom one could be direct (short D4). Often, one does not need snubbers or the extra freewheeling diodes during simulation, as the parasitic inductances are often not included in SPICE models.
This is fed by external triangle generator right? so are you talking about the comparator output to be in out of phase? like Q*? instead of Q on the output of the comparator? I tried but it seems there is a problem with the spice model? if anyone has working spice model of it that would be great. The si8244 indeed has good potential as per specs but would atleast see a waveform before there are any mistakes in the schematic it. Did the bootstrapping capacitor changes as what you said still no output window opening. The sim goes slowly from 90% till 100% but it doesn't move from there. I tried another model of IRS20957 but that works as expected in the ltspice but this one is not working as expected. Can anyone guide me on how that is done with this lib
Not exactly, I'm talking about the overall polarity of the global feedback that you've applied from the output of the amplifier. A gate driver could be inverting and you need to first get the open-loop version working, and check for the correct polarity before closing the loop around the whole thing.
All gate drivers whether IR or Skyworks or any other simply function like high output drive logic devices with a floating high side. However, the propagation delays and logic polarity could be different.
Does the SI8244 work in open-loop ? If not, this is a software-related problem.
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I tried as what you said but its not simming. Anyway I think I have to work with the schematic as is any suggestions in the above circuit would be very helpful.
If the open-loop schematic doesn't work then it maybe a defective SPICE model and you may have to contact the manufacturer (Skyworks Inc.) for any remedies.