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Piggy backing Driver Chips?

YT2095

I`m in the building stage of a Robot, and am currently going through my box of assorted stepper motors and hooking them up to circuit I`v built and writen the driver s/ware for.

I`m using the SN754410NESN754410NE dual H-Bridge as the driver.

I have (or rather Had) 10 of them this morning, and have catalogued a good 50% of my motors so far in terms of wiring sequence, there motors range in Current and voltage.

I blew a chip this morning, seems it didn`t like 24v without current protection! LOL

anyway, I have some 1.4A motors and wondered if it`s possible to piggy-back these chips to effectively double the current capacity to 2 Amps?

It won`t be a Physical piggy-back, just simply the pins all connected 1 for 1 on a seperate area of board real estate, each chip with it`s own heatsink.

 

I can`t see any Technical reason why this shouldn`t be possible, it`s a Digital signal fed in and at a relatively low frequency.

 

so if any amongst you have any reason Why these 2 chips shouldn`t be married this way, speak now or forever hold your peace! image

  • in reply to YT2095

    I would fit current sharing resistors in series with each driver pin and mesure the voltage drop across them when it's working . If the current shares very well you can reduce the value of the resistors to possibly zero (but then it will be harder to measure the pin currents image).

    I would start off with 0.47R but hope to drop it to 0.22 later.

     

    Michael Kellett

  • in reply to YT2095

    I believe that is the way a lot of the new audio amplifiers are built.  They use one driver for the plus signal and another for the negative signal.

    You get an inherent 50% duty cycle and its easier to compensate for distortions.  Not to mention just plain safer to use.

     

    Overall, this has been a fun idea to play with.

     

    DAB

  • in reply to DAB

    Totally agree with the fet.  Efficient and safe.

  • As long as you have a stack of these cheap drivers, why not go for some redundancy and put 3 on a circuit, instead of 2. That way, even if one fails -- for any reason -- you'll still have an adequate reserve. If you want to dress them up, add a resistor-shunted LED in series to each driver circuit to display actual current flow. This might even be a workable solution for a final version, and could actually be more reliable than a single heavy-duty driver (which could still fail from a poor connection, stray conductive substance, component failure, etc.

  • in reply to Former Member

    Hi Suzee,

     

    When these transistors fail, they usually short.  So having three instead of two probably won't buy you much safety and add additional costs.

     

    That said, if you want to experiment with your design, I now a lot of us would be interested in your results.

     

    Just a thought,

     

    DAB