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Thread: IR2153 HO doesn't switch

  1. #11
    .... Silvio's Avatar
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    Quote Originally Posted by bogdan2011 View Post
    PSU:

    Attachment 7217

    Controller board:

    Attachment 7216
    This is a very basic circuit that I see. What is not appropriate is that the gate resistors should not be less than 22 ohms I guess 27 ohms will be better not to load unnecessarily the IR2153. You should also insert a couple of Gate to source resistors with a value of 10K ohms. This will help with switching off of the mosfets between switching cycles. Make sure that your traces leading to the gates are as short as possible.

    I am not sure about this but it seems that you have an auxiliary winding from the main trafo that feeds pin one of the IR2153. This voltage is very critical and should be no more than 15v, however if this voltage is higher than a resistor according to the voltage present from the transformer should be inserted in series otherwise it would burn the internal zener within the IC

    One last note. Measure carefully with the scope to see the waveform at the gates. The low side is measured between gate and ground. The high side is measured between gate and VS. However this is rather critical because if your scope or smps is not isolated (isolating transformer) then there is a chance you blow the scope or smps. Do not measure the high side if you have no means of galvanic isolation from earth ground.

    Is it possible to post a couple of pictures of your setup?

  2. #12
    I've added 33ohm gate resistors and 10k discharge resistors. Now the high side looks better but I still get a large current flowing. I've also added a 12V zener diode at VCC of the controller, just in case.
    The SMPS is powered from an isolated autotransformer, and the scope is not earthed. The measurement in the video is for the high side. I don't have a differential probe and I can't measure the low side at the same time, so I assume the switching is complementary (at least that's how it was with the test circuit).

    https://youtu.be/rRqB7iMdFTI
    Attached Images Attached Images

  3. #13
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    @Bogdan 2011,

    With the video that I saw and also the changes you have made it seems that there could be something wrong somewhere. It also could be the case that there may be a shorted turn in the transformer.
    The IR2153 usually present a very nice square wave and the spike in the rise time may be also a reflection of the output inductor.
    For an unregulated supply the output inductor is not really needed and only maybe a small one of say 3 to 6uH is needed here.

    Please note that the duty cycle is near 50% in the IR2153 and hence the wave is not chopped as in a regulated smps. This is why you do not need the output inductor. An output inductor will induce losses and voltage drop at the output. It will also generate spikes across the primary winding. A small one such as 3 to 6uH will help block out switching noise at the output. Try also fitting a 1uf capacitor at the output it will help very much for a clean output.

    Some suggestions:-
    1) If you have one try to hook up a used transformer from a computer power supply (the frequency for these is usually around 20 to 30KHz)

    2) If you do not have one disconnect the transformer from the pcb and hook a a small lamp of say 15w-25W instead at the primary of the trafo terminals. You can check again the wave form. If the problem still persists then it could be that the chip is not good. I do not know when you tried the pin header on the breadboard how it performed and how the waveform looked. If on the other hand the waveform is nice then it could be the transformer at fault.

    3) You may also need a snubber across the primary of the trafo. This will help eliminate any spikes generated between each cycle. Usually a 470pF X 1kv and say 40 to 100 ohm resistor in series will suffice. The resistor for the snubber should be at least 2watts.

    4) Try to disconnect the double diode at the output and check again. It could be the secondary winding orientation may be in the wrong direction.

    5) You are doing the right thing measuring the high and low side ONE AT A TIME AND NEVER TOGETHER.

    I hope this helps to solve your problem.
    Last edited by Silvio; 04-07-2020 at 07:38 AM.

  4. #14
    These are the waveforms of the test circuit. For some reason, the high output is lower in amplitude. I've measured it both referenced to ground and to VS. The LO amplitude is around 11V and the HO around 6V, and that might not be enough to turn the high side transistor properly.

    IMG_20200407_115139.jpg

  5. #15
    diysmps Senior Member
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    im sorry late reply wait i see your circuit, this smps ir2153 is very simple and easy to make, but the condition for test run must use light bulb, then i would like to notice you this cjip does NOT include in rush current which when you make secondary more than 24vdc it will spike at high side primary winding which will create huge spike high in rush current from the main supply which this chip ir2153 cannot handle it, so what you need is to create relay plus resistor to prevent this, we call it SOFT START. its recommended soft start for high voltage and high current at secondary when you make output 30vdc and above. or you put big caps bank at secondary also will cause this in rush current at primary. to protect this you need to make SOFT START from main supply, easy to make, for me i use 470 ohm resistor for 10 second then releay release it, i use from main to make soft start, 470nf + 10 ohm, then bridge rectified go through 13v zener then i have simple circuit for simple soft start. LET ME SEE YOUR CIRCUIT.

  6. #16
    diysmps Senior Member
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    first, on control board put zener diode, gate resistor must be 22ohm and above for irf740, zener need each gate hi and lo, and bootstrap caps change from 1u to 100nf, change rt and ct to 10k and 1nf, AVOID big CT 10nf it will increase deadtime, you should lower ct and and calculate with RT is better. like i said above, this chip dont have soft start for high current, so use soft start for it, i never blown my ir2153 so far, and none broken yet even i push it to the limit, just voltage drop, its because of small trafo cannot produce alot power, also mosfet. ir2153 consider easy to make and simple , with step i tell you so i hope you ccan make it. i have many ir2153 circuit include protection at start. irf740 gate must be 22 and above.

  7. #17
    diysmps Senior Member
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    that zener is 1n4148 sorry i forgot to mention

  8. #18
    diysmps Senior Member
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    im enjoying high quality class d amp now lol tl494 hahahaha, running at 212khz, with irfz44n at +52vdc and 0. this is single supply amp. high freq more efficiency means less distort

  9. #19
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    Quote Originally Posted by bogdan2011 View Post
    These are the waveforms of the test circuit. For some reason, the high output is lower in amplitude. I've measured it both referenced to ground and to VS. The LO amplitude is around 11V and the HO around 6V, and that might not be enough to turn the high side transistor properly.

    IMG_20200407_115139.jpg
    That is quite normal and the reason is that the high side is charged from the capacitor and not from direct dc. In circuit it would behave differently and do not worry the voltage at the high side gate will be the rail voltage (12v) less the diode voltage drop around 0.6v. One other detail to drive an IRF740 a 470nF film capacitor is a better choice. This is more than enough for it. I seen a lot of commercial amplifiers using smps and even when driving large IGBTs and mosfets the bootstrap capacitor is not more than this value. What I usually notice is that they put a film type rather than an electrolytic capacitor. The reason for this is that here this capacitor takes a lot of beating and must be of good quality and low esr.

    One last thing I want to mention. Put a 100w bulb in the input for current limiter. Do not be fooled by the input current read on the DMM. This will be seen larger than normal due to that at idle the smps has a power factor of 0.5 and the current drawn is due to this rather than that of what really the smps is consuming.

    The flickering of the input current limiter may be the case that it is lowering a lot your input voltage. (this is why I suggested a 100w lamp) This in turn the auxiliary winding feeding the smps may not have enough voltage to sustain the expected 12v to supply the rail voltage. The start up resistor however will be facing the same problem and hence the high side gate may not have enough voltage to be driven as it should.
    Last edited by Silvio; 04-07-2020 at 07:45 PM.

  10. #20
    The flickering of the input current limiter may be the case that it is lowering a lot your input voltage.
    This is true, my test bench variac can't hold the current drawn by the power supply, so the voltage drops quite significantly. But then without the bulb I have burned 2 pairs of transistors and a few fuses (hence the litz wire in place of the fuse holder). In the video, I was gradually increasing the voltage until the chip started switching, then the bulb starts to light up, so the current draw must be high. The reading on the DMM was the output voltage.

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