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  1. #81
    Join Date
    Dec 2011
    Posts
    17

    help me

    Hi H500,
    I don’t understand about “the advantage of low impedance and temperature compensation”. This is so strange for me, if you can pls share document about this then I try to study.
    For the standby current reduction circuit, we will add more sub-circuit as attached file. But I’m not sure whether it can work or not?
    I try to understand about Q5, Q7, Q6, R19 and R27 as follow:
    + Q5 and Q7 always “ON” -> Vbe of Q6= R27(12/ (R27+ R19)) = 2k(12/17,4k+2k)=1.237V -> Q6 “ON” -> 12V at node Emitter Q6&C12&R30&R31 (it should be 0.5V per ohm into the resistor network) -> this is very illogical for me – pls help me clear.
    Pls also say about R23, how many value which we follow.
    Attached Files Attached Files

  2. #82
    Join Date
    Jan 2005
    Posts
    1695
    Ghoang,

    I don't know if the 1/amp per K formula works or not. It does not matter. Just connect a scope across r39 and change r27 until you get the desired current.

    If you're interested in detailed calculations, you will need to do some work first. Show me your attempt at it and I will help you if necessary. You can also use a simulator such as Pspice.

    As for the standby, your circuit should work but you don't need another chip. The cpld code already has a standby timer. (see stby on the schematic) Just route it's output to an i/o pin.

    Did you build the circuit yet?

  3. #83
    Join Date
    Dec 2011
    Posts
    17
    hi H500!
    I haven’t built this circuit yet and trying to learn before building.
    If you have working board, you can share PCB design experience about CPLD or any important note during design PCB, I only have a Mariss’s document about H-Bridge design.
    For the calculation: I haven’t really understood about current monitoring circuit yet so I can’t attempt. I will try to understand more. This is very necessary for me so I don’t have oscilloscope, only have multi-meter.
    For Standby: if i want use the CPLD pin#18 to control “ON/OFF” standby resistor then can you show me code and connection? I’m not good VERILOG language.
    For map VERILOG code to CPLD pin: can you share Constraints file for ISE compiling.
    The schematic was hiding something such as: - adding 1M ………, inside box near LM431 (U1).
    What is the purpose of R23?

  4. #84
    Join Date
    Jan 2005
    Posts
    1695
    Ghoang,

    Keep in mind that Mariss presented the project as a learning tool. The calculation might not be accurate. If you don't have a scope, put an ammeter in series with one of the motor coils. Replace r19 with a fixed resistor so you don't accidentally turn it too far and destroy your board. Replace r27 with a 5k pot. Then you can just adjust it until you get the desired current. But make sure you have a solid connection. If you connect or break the coil circuit while the power is on, you will likely destroy the mosfets.

    I did not implement the standby current on this design yet. I just learned verilog for this project and I'm no expert, but adding a line similar to assign MY_PIN18 = STBY? 1'bz : 1'b0; will do the job.

    Some notes in the schem were hidden because they were experimental and not relevant to the final design.

    R23: It offsets the waveform slightly to prevent cross over distortion. You can adjust it until the motor vibration is minimized.

  5. #85
    Join Date
    Dec 2011
    Posts
    17
    Hi H500,
    Thank for great support,
    I have just received 5 pcs XC2C64 in this afternoon. i am drawing PCB on eagle, i think i can finish on next week.
    R17: i replaced by 1x16.9Kohms resistor + 1x1Kohms POT.
    for the H-Bridge: i think SCH was lacked some resistors which protected latch-up mosfet. i will add more in my PCB.
    I will post SCH to thread then can you help me double check?

    Thank in advance.

  6. #86
    Join Date
    Jan 2005
    Posts
    1695
    Ghoang,

    Post your schem and I will give you my opinion.

    What do you mean by mosfet latchup? If you're referring to the diodes across the fets, they are not needed. I have been using this circuit without any problems.

  7. #87
    Join Date
    Dec 2011
    Posts
    17
    Hi H500
    Latch-up mosfet happen when CPLD don’t drive IR IC then Vgate of mosfet auto rise up high level and lead to shorted circuit at low side and high side mosfet, I met this problem in the past when i built H-bridge with IR2184 and IRF540, mosfet was burn when I turn on power. Finally, I add more resistors between Gate and source all mosfets then issue has gone.
    I will try to finish schema today.

  8. #88
    Join Date
    Jan 2005
    Posts
    1695
    Ghoang,

    That's a good point. The datasheet is unclear about whether the gate drives ever float. Adding the resistors might be a good idea, just in case.

  9. #89
    Join Date
    Dec 2011
    Posts
    17
    Hi H500,e
    I enclosed schema, pls give your opinion.
    Schematic has some differences with original design so my country don't have some components:
    1. Replaced IRF530 by IRF540N.
    2. Replaced BAS516 by BAS316 (BAS316 take out from old laptop mainboard).
    3. Replaced diode ES1D by 1n5819.
    4. add more standby current reduction as your instruction.
    5. add more 8 resistors connect between Gate and Source 8 mosfet (i explained in post #87)
    If this schema is ok,i will continue to run PCB.
    Thanks.
    Attached Files Attached Files

  10. #90
    Join Date
    Jan 2005
    Posts
    1695
    Ghoang,

    Your schem looks good. Instead of the 1n5819, you can use bas316 also. On my dsp board, I used bas516 everywhere.

    Ideally, c29,30,33,34 should be about 10x bigger than the bootstrap cap. I didn't do that, but I included an on board 50u electrolytic capacitor on the 12v supply on some of my designs.

    Are you a doing surface mount or through hole pcb?

  11. #91
    Join Date
    Dec 2011
    Posts
    17
    Hi H500,
    Thank for your advice about diode
    almost i use 0805 SMT component.
    today is holiday so i will try to finish PCB and post to thread so that you help me give out opinion.
    Best regards.

  12. #92
    Join Date
    Dec 2011
    Posts
    17
    Hi H500,
    I finished PCB, pls help me give your opinion on PCB
    I followed Mariss's document to drawing H-Bridge.
    If you have Eagle cad-soft pls let me know then i will attached original file.
    Thanks.
    Attached Files Attached Files

  13. #93
    Join Date
    Jan 2005
    Posts
    1695
    Ghoang,

    The ideal position for the ir2104 is below the mosfets. That will minimize the trace inductances and the chance of getting unexpected voltage spikes. The power section looks good. Give it a try.

  14. #94
    Join Date
    Dec 2011
    Posts
    17
    Hi H500,
    You commented about minimize the trace inductances from IR2104 to mosfet or from CPLD to IR2104 so i mean arangement trace from IR2104 to mosfet is the shortest.
    Thanks.

  15. #95
    Join Date
    Dec 2011
    Posts
    17
    Hi H500,
    I modified PCB follow your comment, Pls check and advice one more time.
    Thanks
    Attached Files Attached Files

  16. #96
    Join Date
    Jan 2005
    Posts
    1695
    Ghoang,

    It looks good. Are you planning to make it yourself, or send it to a pcb company? If you're using toner transfer, keep in mind that the holes will not be plated. The pads and vias should be at least 500mil to make sure there's enough copper to solder to.

    How do you plan to heatsink the fets? If you're using the Geckodrive method, you will need two holes for the clamping screws.

  17. #97
    Join Date
    Dec 2011
    Posts
    17
    Hi H500,
    I will sent file to a PCB vendor when everything is OK,
    my pcb was lacked heat-sink for mosfet, thank for your reminding. i never see Gecko driver, can you show me about heat-sink on heat-sink driver so that i can copy to my PCB.
    best regards

  18. #98
    Join Date
    Jan 2005
    Posts
    1695
    Ghoang, see the photos in post #7 in this thread.

    Difference between Leadshine M542 and iCan 2m542 - CNCzone.com-The Largest Machinist Community on the net!

    I put one screw near the center of 4 fets to clamp the pcb on top of them. I found that it is tricky to get all the fets to make solid contact with the heat sink. An alternative might be to make 8 holes in the pcb to allow a screwdriver to be used to tighten each fet.

  19. #99
    Join Date
    Dec 2011
    Posts
    17
    Hi H500,
    Thank for your support, i will send file to PCB vendor soon.
    Any problem during testing Driver,i will let you know.
    Thanks.

  20. #100
    Join Date
    Mar 2012
    Posts
    6
    Hi; I've build a driver using H500 schematic and the jed file (10µstep) the stepper run smooth but there isn't torque enough in the stepper just like if it the driver is outputting 1 amp or so, my stepper are nema 34 /5amp, I used 4.7k resistor (R27) to set current output to about 4.5 amp;I'm using ir2104s and irf 540N mosfet I have also used byv27 as mosfet gate diode (in serie with 220 ohm resistor) and a 15 ohm in parallel to them (diode+resistor) the bootstrap caps are 0.33 µf
    I have measured voltage in the Lm393 input (pin 3 and 5) and it's 0.28 to 0.3 volts so I was supposed getting full power from the driver (6 amp as I'm using 5mil sense resistor) but unfortunately the motor stall rapidly (I can hold the rotor with my hand easily) ,what could be the problem any help please ,Thanks

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