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Description: This is a breakout board for the fully integrated Hall Effect based linear ACS712 current sensor. The sensor gives precise current measurement for both AC and DC signals. Thick copper conductor and signal traces allows for survival of the device up to 5 times overcurrent conditions.

The ACS712 outputs an analog voltage output signal that varies linearly with sensed current. The device requires 5VDC for VCC and a couple of filter capacitors.

Features:

  • x05B (5 Amp) version
  • Low noise analog signal path
  • Device bandwidth is set via the FILTER pin
  • 5us output rise time in response to input current
  • 80kHz bandwidth
  • 1.5% output error at 25 degrees C
  • 1.2mOhm internal conductor resistance
  • 2.1 kVRMS minimum isolation voltage from pins 1-4 to pins 5-8
  • 5.0 VDC, single supply operation
  • 66 to 185 mV/A output sensitivity
  • Output voltage proportional to AC or DC currents
  • Factory-trimmed for accuracy
  • Extremely stable output offset voltage
  • Nearly zero magnetic hysteresis
  • Ratiometric output from supply voltage

Documents:

Comments 32 comments

  • If you’re using this to monitor DC motor current, watch out for the motor magnets. When mounted a couple inches from our PM DC motor we got a huge (~0.5 amp) offset in the ACS712 output. So, back to the sense resistor for us. Aside from that the ACS712 seemed good.

    • These chips are part of allegro’s hall-effect sensor line … so yes they are going to be sensitive to magnetic fields

  • Is there any chance we could get 20 of “ACS712” in one board?

  • I vote for the 20 amp version as well. I would buy a few of them right now.

  • Is there any chance we could get this board with the 20 or 30 amp IC?

  • the 1nf cap should be included.

  • If we are measuring AC current, does it matter which terminal we connect the hot and neutral to?

  • I have a line that sometimes carries 230V AC and other times ~400DC when it is rectified. I could not identify from the datasheet if AC and DC have different properties for this sensor, if voltage is much of an issue or if it is ONLY the current it senses…

    I will probably swap out the op-amp for a peak detector amplifier, I just need a Current/No Current detector that does not need re-calibrating with every current change . Can anyone advise me!!

  • When measuring AC current, does it simply give a sine wave output voltage centered on Vcc/2? I didn’t see anything specific in the datasheet about AC input/output, just that the output is above Vcc/2 for positive current and below Vcc/2 for negative current. So that’s why I’m thinking that it just gives me the corresponding sine wave output (again, centered on Vcc/2). If so, has anyone used it with a microcontroller to measure AC current? And if so, how did you rectify the output into a suitable DC voltage for the ADC? I’m guessing the simplest way (which isn’t so simple) is to run the output through an op-amp to stiffen its output impedance (and besides that, I need to amplify the output anyway because I’m measuring fairly low AC current, less than 250mA) with Vcc/2 as one input thereby centering the op-amp’s output signal at ground (the datasheet shows an example of that; also, without split power supply rails, an AC signal into an op-amp would just give me every other “hump” of a half wave output, like one side of a center-tap xformer), possibly cap it to reduce the ripple, and then run that final output into the ADC. The last thing I want to do is bring in split power supply rails just for getting a better rectified AC output. What a mess…

    Has anyone does this? I feel the coming pain of lots of testing and screwing around to get this right, so I’m hoping someone’s already done this who’s willing to help a brother out :)

    Thanks in advance for any ideas at all! :D

  • alright, the example code in the Wiring Example is meaningless. I’ve tested my code with both ACS712-05B and ACS712-20A versions. Accuracy is within =- 3mA

    code: https://forum.sparkfun.com/viewtopic.php?f=6&t=33605&e=0

  • I just tried using the ACS712 board but for some reason I only get 0.60v of response from the Vout even if i don’t put any current source, which should give me 2.56v if the Vcc is 5v. Could it be that it got burnt when i was solding it? Or is there another posibility?

  • what kind of header can you use for the big holes?

  • Just a quick warning to not use this to sense your main Utility Line. Most of them in the US have a 200A breaker, which means that you could see as much as 200A in the line, which from the description above sounds like it would burn out the sensor.

    That said, most house circuits have 20A breakers, which shouldn’t burn out this part, but it might not give you the data you want.

    • For sensing current through the mains, you’ll probably be much better off (and safer) using a clamp-type current sensor such as the SEN-11005 in the related products below.

  • Hi All,

    Is it possible to use this sensor to measure the input voltage being supplied to the controller to which this sensor is attached? Or is this only used to measure voltage/current on everythign but the power source to allow the sensor to operate?

    Thanks

  • Noob question here: What terminals should I add to the current pads to connect 14AWG wire?

  • i would suggest uploading a new photo of the red PCB

  • 30A demo board
    There is also a 20A demo board.

  • hows about getting a version of the ACS714 like Pololu?? A +/-30amp version is a bit more suitable for robotics. I have used them and they work very well, would probably fit on this board.

  • Here’s a link to the Allegro dev kit for 20A:
    http://www.allegromicro.com/en/Products/Part_Numbers/0712/ACS712_Demo_Board.pdf
    note that’s 4oz copper on top/bot with via stitching… see page 7 of the above link
    … most quick turn PCB’s houses don’t do that heavy a copper… and if they did it would be $$$
    Link to the store $20.00:
    http://prostores2.carrierzone.com/servlet/AllegroMicroSystems/Detail?no=386

    Not sure if its in stock tho…

    WAM
    http://home.comcast.net/~ajawamnet/wc/wamcover.htm

  • Don’t you think this is a bit overpriced?

  • Could we get the cross sectional area, conductor width, and #oz. copper for the current traces? I’d like to compare them to the IPC Temperature Charts to see if your breakout board (with the ACS712-5A already supplied) can handle the 30A version.
    Or, if it’s already been proven to work superbly under that condition (tested at 30Amax), I could just take Sparkfun’s word for it. Thanks!

  • Suggestions for the next revision:
    Mark the ‘positive’ current direction on the board mask, for the two big holes (with an arrow ideally, or + and -).
    Also, standard size holes for the current connectors would be nice, to make it easier to connect headers. Perhaps in addition to the big holes?

  • I’d like to solder some standard male headers to the current pads, in order to be able to plug the board into a breadboard for prototyping.
    Could anyone advise as to if that would work (filling the remaining space with solder), or give some tips?

    • It would work, it would just be clunky. Use the breadboard as a jig. Make sure you don’t get a massive blob of solder onto your breadboard.

  • Is there a description of how to calibrate these things online anywhere?

  • Anyone know if this is suitable for the mains? say 3A max @ 240v AC (UK). I had a quick skim through the datasheet, and didn’t seem to find anything :/

    • I’m using the 20A version of this chip in a device to sense mains current @240V/50Hz (Australia). It handles it just fine.

    • the ACS712 is rated to 5A and after searching around on the web for projects using this ic at 220v i would say its usable in europe. the datasheet mentions a Peak Basic isolation voltage of ~380 Volt which could be the maximum voltage the ic can handle. i hope this answers your question.


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