How can any TB6560 driver design NOT violate the chips spec's?


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Thread: How can any TB6560 driver design NOT violate the chips spec's?

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    Registered James Newton's Avatar
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    Default How can any TB6560 driver design NOT violate the chips spec's?

    I've been reading the TB6560 driver chip data sheet.. you can find it here:
    http://www.toshiba-components.com/mo...3_20080407.pdf

    The interesting part to me is on page 28, where it says:
    Power-on Sequence with Control Input Signals
    Turn on VDD. Then, when the VDD voltage has stabilized, turn on VMA/B.
    Hold the control input pins Low while turning on VDD and VMA/B.
    (All the control input pins are internally pulled down.)
    After VDD and VMA/B completely stabilizes at the rated voltages, the RESET and ENABLE pins can be set High. If this sequence is not properly followed, the IC may not operate correctly, or the IC and the peripheral parts may be damaged.
    ...
    A power-off sequence should be the reverse of this sequence
    So... there are a couple of thoughts that come to mind after reading that:

    First, has anyone ever seen that documented in the operating instructions for a TB6560 based driver? Like all those cheap ones from China and Hong Kong that are being sold on ebay.. do ANY of those say "um... by the way, don't turn on the motor power until after the logic voltage is up, and turn off the motor power before you shut down logic power."? Or do any of them have some magical circuitry to prevent the motor power from coming on until after the logic supply has settled?

    Secondly, how on earth would you even do that in a driver that depends on a separate power supply? Keeping the logic power on after motor power goes down isn't hard, the caps in the regulator circuit will do that, but the power up sequence is the trick. If you were building a complete system, and you could build two power supplies (one for logic supply and one for motor supply) and you built in a timing control that flips on the one first and then the other, then, yeah... that's possible. But if you just sell a driver, and you have the user hook up any old power supply for motor and logic without warning them... or you have an onboard +5 regulator to supply the logic power from the motor power supply... how do you set that up so it doesn't fry the chip?

    I started off wondering why so many people who buy these crap TB6560 drivers end up frying the chip, and NOW, I'm wondering how any of them work at all!
    http://www.cnczone.com/forums/genera...y_chinese.html
    I started looking into this after reading:
    http://www.cnczone.com/forums/genera...se-24.html#281 so I'm not the only one who has noticed this problem...

    I'd honestly like to hear if there is a good electronic solution to that problem. I'm not an analog electronics expert, or a power systems designer by any means. Maybe there is some way of doing this power up sequence with ONE power supply that I've not heard of?

    The capacitors and current limiting in a standard +5 voltage regulation circuit pretty much guarantee that it will come up to +5 volts slower than it's supply voltage turns on. I guess you could add a great huge power resistor between the motor supply and the chip and put a great huge high voltage capacitor right there so it also comes up slower but A) high wattage resistors and high voltage high value caps are expensive and B) you would loose supply power due to the resistor. That's why people didn't like the old style of linear supplies.

    Another obvious idea would be a relay, but then you are controlling an inductive load and as soon as the relay breaks, you are going to get a nice healthy back EMF spike which will kill the chip anyway. (Datasheet, page 32, point 3).

    I guess you could hook your motor power supply INPUT up to a relay... but then you need a separate supply for logic power again...

    Bottom line: TB6560 = 2 separate power supplies and the first one has to turn on the second one after a time delay. OR... it's going to fry eventually. No?

    Similar Threads:
    Last edited by James Newton; 10-27-2011 at 11:04 AM. Reason: typos and power down clarification.


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    Other TB6560 documentation:
    http://www.semicon.toshiba.co.jp/doc..._en_090324.pdf mostly how to (not) make it smoke.



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    Gold Member doorknob's Avatar
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    I had a brief discussion of the power sequencing topic with another cnczone poster a few months back - he was building his own driver board based on the TB6560.

    I don't remember how he decided to handle it, but maybe I can find that thread.



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    Quote Originally Posted by doorknob View Post
    I had a brief discussion of the power sequencing topic with another cnczone poster a few months back - he was building his own driver board based on the TB6560.

    I don't remember how he decided to handle it, but maybe I can find that thread.
    I'd be very interested to see that... I did a search for any posts from you with TB6560 in them and I don't see any mention of that issue in those posts... could easily have missed it... Thanks for your interest.



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    I thought about uaing the spindle relay to do the power sequencing.
    I want to connect the regulators directly to power source, tb6560 motor power switched by relay and relay coil to the 12V regulator.
    In this way the motor power will be switched on after 12V regulator output has reached a reasonable value.

    A 100ohm resistor in parallel should be useful to prevent power spikes on the relay contacts (the dissipations shouldn't be a problem given the limited amounth of time it will be off).



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    Gold Member doorknob's Avatar
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    Quote Originally Posted by James Newton View Post
    I'd be very interested to see that... I did a search for any posts from you with TB6560 in them and I don't see any mention of that issue in those posts... could easily have missed it... Thanks for your interest.
    The discussion about a DIY TB6560 controller starts with post #56 in the following thread:

    http://www.cnczone.com/forums/diy-cn...cb_mill-2.html


    I raised the issue of startup timing in post #58, and the OP mmcp42 alluded to it in at least posts #59 and #60. I'm not sure that any definitive resolution of the issue was arrived at, though.


    Quote Originally Posted by doorknob View Post
    There are some other possibly interesting quirks that I'm unsure how you would want to handle.

    For example, the discussion on page 28 about start-up timing seems to say that both VDD and VMA/VMB need to reach their specified voltages before RESET goes high, but in your circuit it looks like RESET is asserted only after VDD is turned on. Are we really to believe that, as the note states, bringing RESET high (for example) in the absence of the motor voltage being present can destroy the chip?




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    Quote Originally Posted by ToshiroTamigi View Post
    I thought about uaing the spindle relay to do the power sequencing.
    Right, I'd thought of that as well... it does mean you can't jog or move the axis until the spindle is running...

    Quote Originally Posted by ToshiroTamigi View Post
    I want to connect the regulators directly to power source, tb6560 motor power switched by relay and relay coil to the 12V regulator.
    In this way the motor power will be switched on after 12V regulator output has reached a reasonable value.
    Not sure where you are getting 12V from... is that the logic supply voltage for your driver? I guess the board itself regulates that down to 5V?

    Keep in mind, if you just switch the OUTPUT of the motor power supply, you will kill the drivers via back EMF when you power down. You MUST switch the INPUT to the power supply, and have a separate logic power supply.

    Quote Originally Posted by ToshiroTamigi View Post
    A 100ohm resistor in parallel should be useful to prevent power spikes on the relay contacts (the dissipations shouldn't be a problem given the limited amounth of time it will be off).
    Well... I'm not an analog / power engineer, but I'm pretty sure that will not prevent the back EMF kick.

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


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    Quote Originally Posted by doorknob View Post
    The discussion about a DIY TB6560 controller starts with post #56 in the following thread:

    http://www.cnczone.com/forums/diy-cn...cb_mill-2.html


    I raised the issue of startup timing in post #58, and the OP mmcp42 alluded to it in at least posts #59 and #60. I'm not sure that any definitive resolution of the issue was arrived at, though.
    Thanks for finding that doorknob... As you say, it appears to have not been resolved and later in the thread he moves to other drivers.

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


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    The relay will not be managed by spindle output. It's coil will be connected directly to the 12v regulator onboard.

    The emf will be handled by the diodes at tb's outputs(togheter with the tb6560's internals). I only need to revise the topology of the supply diodes to better cope with them.
    I'll post a schematic as soon as i'll found a couple of free minutes.

    Last edited by ToshiroTamigi; 10-28-2011 at 01:52 AM.


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    Mariss Freimanis posted this on another thread but I wanted to quote it here because A) it's brilliant (as usual) and B) it points out exactly what (I think) happened with the TB6560:

    Quote Originally Posted by Mariss Freimanis View Post
    I would like to offer some general opinions regarding monolithic motor driver integrated circuits. A monolithic motor driver IC integrates low-level control circuitry with a power stage able to drive a motor in a single, neat and ready to use package. That is the promise anyway; unfortunately the execution usually falls short for one or more of the following reasons:

    1) Custom (application-specific) ICs are very expensive to design. Usually a big client approaches an IC manufacturer and says "I have motor application for a printer and I will need 10 million ICs designed for controlling this motor to these exact application specifications."

    The client signs a contract that allows the IC manufacturer to sell the resulting design after the client's needs are met in exchange for monetary considerations.

    The IC manufacturer then free to sell the IC in the marketplace as a generic device. Unfortunately, the device only meets one customer's requirements exactly, the one who commissioned the device in the first place. Everyone else afterward who buys it has to deal with the idiosyncrasies built into the device as specified by the original client.

    2) An IC manufacturer learns from their client base and attempts to build a generic motor IC on their own which should satisfy everyone. The manufacturer may be a top-rate IC designer but that doesn't mean they are top-rated motor drive designers.

    Allegro comes to mind here; they have nicely executed ICs that make very fundamental design mistakes in understanding what's required to make a motor happy. An example is their recirculating, non-recirculating mode switching depending on what angle you are on the sine-cosine reference. It is a naive misjudgement of practical drive requirements.

    I don't mean to single Allegro out, there are design criticisms for all the other monolithic ICs as well.

    3) Integrated circuits are exquisitely sensitive to temperature gradients. They depend on a constant temperate across an IC silicon chip. Manufacturers constantly combat thermal gradients across an an IC to to guarantee it will work properly. To an IC designer, a motor drive is an IC from hell. There is the motor section that generates enormous heat and that heat interferes with proper operation of the control section of the IC. Motor drive ICs are not reliable devices; it's why they smoke easily.

    4) Manufacturer's marketing departments over-spec the devices they sell. A good example is the L297 / L298 chipset. It was touted as a 2.5 A rated IC even though no sensible engineer would ever use it with motors over 1 Amp.

    I have seen the L297 / L298 chip-set, the various Allegro offerings and the currently popular Toshiba IC come and go. In my opinion they are all doomed to failure for the reasons mentioned. Don't worry, there will be another new one next year and it will have the same fate.

    Mariss
    The TB6560 is a perfect example of #1 above (not to mention #3 and #4 as well). This thing was designed to be used in a /system/ where the power supply sequence was carefully controlled. It obviously had a logic power supply, and a microcontroller that would fire up, hold the chip in reset, THEN enable the motor power supply and complete the power up sequence with the TB6560 control lines. Easy when you are designing a complete system, quite difficult when you are designing a separate stepper driver.

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


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    My experience with the 6560 failing is the quality of VMA and VMB at the chip leg itself. However, if a design is just thrown together not taking into consideration proper power supply timing for power up and power down, that will be an issue as well.

    As to the Mariss post, some points are valid, some are Gecko sales oriented. I'm sure STmicro engineers would take issue with him....

    In general though, monolythic stepper ICs are geared to consumer products, specifically printers. CNC usage is not why they are designed, but some of the chips work fine for hobby machines.

    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com


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    Hey Phil, thanks for taking the time to reply. Could I ask for a tad more information? What do you mean by "quality"? Things like kick back? wire coming loose? Spikes? Over-voltage?

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


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    Has there actually been a lot of failures caused by the timing issue? Violating design requirements is not a good practice, but it will not necessarily result in damage.



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    Quote Originally Posted by H500 View Post
    Has there actually been a lot of failures caused by the timing issue? Violating design requirements is not a good practice, but it will not necessarily result in damage.
    There have been GOBS of failures of these drivers, but there is no way to know for certain if this is what caused those failures. However, when the data sheet for the chip says "don't do this" and every driver out there IS doing this, it seems like a good place to start, doesn't it?

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


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    A lot of the failures on the small SMD stepper driver chips come from the enthusiastic specs. These tiny chips are designed for bubblejet printer use which is intermittant use at lowish currents and with low dynamic loads. The max amps spec are definitely enthusiastic, ie if rated for "3 amps" that does NOT mean "3 amps all day long driving a big dynamic CNC machine".

    The last stepper chips that had more realistic specs were the SLA series, (as used in the SLAmStepper and Hobby CNC boards) that have a much larger chip die, larger body package and greatly increased heatsink surface compared to any of the cheap disposable type SMD stepper chips like the TB6560.

    The SMD chips (like the TB series) are just not meant for proper machinery! They are meant for infrequent use, in small throwaway consumer devices like bubblejets and laserprinters.



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    Quote Originally Posted by RomanLini View Post
    The last stepper chips that had more realistic specs were the SLA series, (as used in the SLAmStepper and Hobby CNC boards) that have a much larger chip die, larger body package and greatly increased heatsink surface compared to any of the cheap disposable type SMD stepper chips like the TB6560.
    I totally agree that the SLA is a better chip. It beats the TB6560 on every metric except one: It's quite a bit more expensive. And... cheap sells over quality it seems. It's also bipolar, and everyone is (incorrectly) convinced that bi-polar is better. It isn't, and I can prove it, but get people to listen... that I can't do. LOL.
    techref.massmind.org/techref/io/stepper/connections.htm

    However... The TB6560 is also available in a full sized package just like the SLA. It doesn't have the SLA's spec's, but it is a full sized chip. Most of the boards that use it, mount the full sized chip as if it were SMT, by actually cutting a hole in the middle of the PCB, but it CAN bet setup vertically just like the SLAm:
    techref.massmind.org/techref/io/stepper/SLAm/SLAm_bld.htm
    Here is one example:
    pminmo.com/toshiba-6560

    Quote Originally Posted by RomanLini View Post
    A lot of the failures on the small SMD stepper driver chips come from the enthusiastic specs. These tiny chips are designed for bubblejet printer use which is intermittant use at lowish currents and with low dynamic loads. The max amps spec are definitely enthusiastic, ie if rated for "3 amps" that does NOT mean "3 amps all day long driving a big dynamic CNC machine".
    Now that is dead on! Half the cheap crap Chinese TB6560 drivers are advertising 3.5 amps when the datasheet /very/ clearly says that is a peak rating. For example:
    CNC TB6560 3 Axis Stepper Motor Driver Controller Board | eBay "High power, maximum 3.5A drive current."

    I guess you can claim that is a language difference issue, but I think it's a bald faced lie.

    I mean, the Linistepper using discrete drivers (TIP122's) that are rated at 8 AMP (!!!) peak, and 5 AMP's continuous, but we NEVER say the driver can do more than 3 AMPs and we have all sorts of scary warnings about how you must have huge heat sinks to drive even that much. Why? Because it isn't practical to drive more than 3 amps in microstepping modes before the heat will overwhelm the driver and kill it. Now, with a CPU fan heatsink, in half step mode, you could probably get away with 4 or maybe even 5 amps drive, and wouldn't that be a great advertising bullet, but it wouldn't really be honest. And we couldn't offer more than a 7 day warranty (seriously, go check the ebay listing, the warranty is 7 whole days! ) much less total customer satisfaction like we do.

    Ok, this is turning into an advertisement. Sorry. My point here is that Roman is right, the TB6560 is a little guy that is being advertised at far more than it's actual ability.

    And my point in this thread is that even with all of that aside, it STILL can't work right because the drivers that use it violate the datasheet requirements. Even if it does work, every single time you power it up, there is a percentage chance that it is going to fry. Eventually, you are going to power on, and it's going to lockup the wrong way and let out the magic smoke.

    Every TB6560 driver design that I have seen is a ticking "bomb", which is going to fry eventually because it violates the chips operating specs for the power up sequence.

    A design that doesn't violate those specs would be cost prohibitive (I think, I could be wrong here) unless it is part of a larger system where the power supplies are controlled by the main units logic.

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


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    Gold Member doorknob's Avatar
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    (with apologies in advance for the possibly rambling, incoherent thinking out loud to follow)

    The peak vs. average current discussion is an interesting one, and it should probably not be limited to discussions of driver chips alone.

    For example, I haven't found an unambiguous discussion about motor winding current ratings either. Can you even trust that when two different motor manufacturers specify a current rating, those current ratings mean the same thing? Or, is there a game of specsmanship going on with the motor ratings as well as the driver ratings?

    The ratings (for the cheap Chinese motors, anyway) seem to be loosely specified at best. Should they be tightly based on specified holding torque ratings as well as temperature rise ratings, so that they respect the envelope of all of the other maximum ratings, or are there some unwritten assumptions underlying the max current ratings, such that they are getting away with ignoring or violating other constraints? Maybe there are other relevant internal construction details that can vary from manufacturer to manufacturer that are hard for the average buyer to quantify (for example, variations in the quality of the materials used, permeability variations, eddy current losses, internal geometry, or whatever).

    Also, while the ratings may be valid for operation with a low voltage and un-chopped current supply (either for holding the rotor stationary or for single stepping), are there any rules of thumb for adjusting the winding current ratings for chopped operation or microstepping?

    Where this all might make a difference is in helping the user choose an appropriate driver and driver setup that is a good match for their motors. Then again, maybe all of this is a "don't care", because as long as the motors work "good enough", nobody really needs to worry about such details (as opposed to the driver current rating discussion, because it's much more likely to smoke the driver chips than it is to damage the motors or get marginal performance, so motor metrics are probably much less of a concern for the average user).

    It would seem that this is fertile territory for some experimentation, but maybe I'm just overthinking this. It's also possible that you have such a discussion on your site and I have simply overlooked it.



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    Quote Originally Posted by James Newton View Post
    There have been GOBS of failures of these drivers, but there is no way to know for certain if this is what caused those failures. However, when the data sheet for the chip says "don't do this" and every driver out there IS doing this, it seems like a good place to start, doesn't it?
    Your point is valid, but the failure rate on these boards does not appear to be any higher than with other chip based designs. Most of the complaints on this site were related to rough running and missed steps, due to the improper design of the opto couplers.

    I would guess that most of the failures would be caused by people disconnecting the motors while the power is on, or by people using a power supply voltage too close the 40v breakdown limit of the chip.



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    Quote Originally Posted by H500 View Post
    Your point is valid, but the failure rate on these boards does not appear to be any higher than with other chip based designs. Most of the complaints on this site were related to rough running and missed steps, due to the improper design of the opto couplers.

    I would guess that most of the failures would be caused by people disconnecting the motors while the power is on, or by people using a power supply voltage too close the 40v breakdown limit of the chip.
    You may be right, and again, there is no way to know for sure, but posts like these:
    http://www.cnczone.com/forums/1016669-post309.html

    http://www.cnczone.com/forums/1017513-post310.html

    http://www.cnczone.com/forums/954476-post235.html

    http://www.cnczone.com/forums/949031-post205.html

    http://www.cnczone.com/forums/846207-post71.html

    http://www.cnczone.com/forums/828596-post51.html

    Make me think that this power on issue is a significant failure source. Notice what they are saying: no motors were connected or disconnected, no changes made to the isolation, etc... These were systems that /were/ working just fine and after nothing more than a power off / power back on, they are suddenly fried.

    James hosts the single best wiki page about motors for CNC hobbyists on the net:
    http://techref.massmind.org/techref/io/motors.htm Disagree? Tell him what's missing! ,o)


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    I bought the 3 axis from ebay and the first time I cycled it off it blew out a driver when I turned it back on.
    The dealer replaced it with a 5 axis unit that I have not even tried to power up
    for fear of blowing this one as well.
    I have read through and bought the timing ic's and I have some darlington arrays I am considering using on the feild coils input,I am just not sure if it will do anything for it if the ground is shared.



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How can any TB6560 driver design NOT violate the chips spec's?

How can any TB6560 driver design NOT violate the chips spec's?

How can any TB6560 driver design NOT violate the chips spec's?