ALLEGRO A3967 PDF

The ASLB includes a fixed off-time current regulator that has the ability to operate in slow, fast, or mixed current-decay modes. Special power-up sequencing is not required. The tabs are at ground potential and need no insulation. Affichages Lire Voir le texte source Historique. These digital inputs control the microstepping mode. This needs to be a 0V to 5V or 0V to 3.

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Also did not have variable current limit or 5V regulator. EasyDriver V2 - This was the second attempt. I had some boards fabbed at Futurlec without solder mask or silkscreen. The board was twice the size of V1, and routed to dissipate heat much better. The 5V regulator was added. I have since modded the completed boards to add the variable current limit. EasyDriver V3 - A refined version of V2, with the variable current limit on the board, and switched to components.

EasyDriver V4. This means you can now control every aspect of the driver chip yourself. You can put the chip to sleep or in reset drastically reducing power consumption. Also, you get to play with PFD signal.

That horrible tiny pot from V3 is now a somewhat larger pot. This allows for a 3-pin cable to your Arduino or whatever you use to drive the EasyDriver. This allows interfacing with things like 3. If you want to supply your own logic power to the EasyDriver, cut jumper SJ1, and supply 3. If you want the EasyDriver to power some small circuit, you can use the 5V or 3. How much current can you pull from here? Well, feel the regulator.

How hot it gets depends upon what voltage you supply to the EasyDriver. Measuring this voltage allows you to calculate the actual max current being supplied to the motor. See the schematic for information on how to do this math. The value of the bulk cap is listed at uF on the datasheet, but 47uF is all that is really necessary. The bigger the better - but the Allegro datasheet says 47uF is fine.

EasyDriver v4. This helps prevent damage during over voltage events. Common Questions and Answers: Q1 My motor says it can only take 2. Will the EasyDriver running from up to 30V blow up my motor or damage it in any way? A1 Nope. Motors are specified with DC flowing through their coils.

But what we are concerned with is maximum current. Or any chopper driver, for that matter. Then it will cut the power to the coil until the current dips down again, then re-apply power, over and over again, about 20, times per second.

Trust me on this. At least to a point. You want to run the EasyDriver with as high a voltage as needed for your application. Lower voltages produce a lot less heat on the ED and the motor but produce lower maximum speed and torque. Higher voltages up to 30V get you more torque at higher speeds, but your ED will get much hotter. You make the decision. Also, the higher the input voltage, the greater chance of frying your ED if your motor wires come undone for some reason.

Most people are perfectly happy running their ED at 12V, and there are tons of power supplies that work great at 12V and are cheap. The technical reason for this is that the Easy Driver is acting like a switching power supply. It is stepping down the voltage and stepping up the current. The coil of the motor is basically like the inductor in a buck converter.

The chopper circuit switches the coil voltage on and off to maintain a constant current through the coil. Note that you can run the EasyDriver with a supply voltage of as low as about 3V. This does NOT mean that you will get good stepper motor performance at that voltage actually, I can almost guarantee you will not.

However, even at 7V or 9V, the torque on most stepper motors is near their max, at lower speed. Where you really need the higher input voltage is at higher step speeds. Try it in your system first - you may be surprised with how much torque can be generated with a smaller current and voltage.

Q3 How much current does my power supply need to produce? So your power supply needs at least 1. However, you can normally get away with less than that and still be just fine. Because of the way a chopper driver works, the driver and motor actually form a sort of switching power supply. The best advice here is to experiment. See the table under question 14 below for some experimental data I took. Huh smarty pants? A4 See above answer. Because of the way a chopper drive works is the real answer.

You can NOT trust any sort of power supply current measurement in order to measure the actual coil current at any point in time. In actuality, it is really hard to measure the actual current being delivered to the coil, even if the motor is not moving. You need a special amp meter attachment for a scope. Also, see table under question 14 below for actual data supporting this answer.

The coil current is not equal the power supply current. Power supply current is always less than the sum of both coil currents. Q5 How do I adjust the current limit? A5 Just turn R16 - the 10K current limit pot. At one limit, it will tell the driver chip to supply up to mA limited by coil resistance and input voltage per coil.

This is because we can never be sure what pot SparkFun uses to build the boards, and some pots are backwards from the others. This means it has a true H-bridge design internally, and sends current both ways through each of the two coils. You can use 4-wire, 6-wire or 8-wire stepper motors. They need uni-polar drivers. Q6 Why does EasyDriver get so hot?

It means that the driver is constantly passing that much current through, and because its internal resistance is not zero, it dissipates some heat. If you turn R16 all the way up so that mA flows through each coil, the entire EasyDriver board will get hot to the touch. You can put a small fan blowing across the board if you want to. But fear not, the driver chip has a thermal cut out at degrees C, so it will protect itself.

The boards have quite a bit of copper pour on them, to maximize heat dissipation, which helps a lot. Also the voltage regulator gets quite hot - this is because the driver chip needs 70mA at 5V for its logic supply. For actual quantitative data, see question 14 below.

I solder headers in the pins of the EasyDriver and put it into a breadboard. I solder the wires on my stepper motor to a 4-pin. The motor should be spinning at this point. Q8 How do I connect my EasyDriver up?

A8 For Version 4. If you solder. The GND pin in the lower left corner of the board is really only there for mechanical support, but it is tied to ground and you can use it as such if you want.

Then it would be easy to wire up as many EasyDrivers as you wanted to drive lots of stepper motors. This means it plugs into a standard breadboard. The GND pin in the lower left corner of the board is really only there for mechanical support, but it is tied to ground and you can use it as such. Why not? And how do I know which way to turn the current adjustment pot? A9 There are some mistakes with the EasyDriver silk screen on previous board revs. On some of the earlier versions the STEP pin is not labeled, and the motor coil output pins are not clearly marked.

You never really can trust the silk screen on the Easy Driver. Instead, what you need to do is put a volt meter on the TP1 test point which is connected to the VRef pin on the driver chip and measure its voltage with respect to ground. The largest voltage on that test point normally 5V will result in the largest current through the motor coils mA , and the smallest voltage on TP1 1V corresponds to the least current through the motor coils mA.

Q10 Man, this is a lot of work to just use the A chip. A10 Sure. Just put the chip down on your own board yourself.

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