Pololu Robotics & Electronics
Menu
My account Comments or questions? About Pololu Contact Ordering information Distributors

Pololu Forum

ACS714 separation


#1

I have purchased to 30A ACS714 sensor boards and wonder whether there is any recommended minimum distance when mounting two together in a case ?

I want to use them to monitor the current flow in two 24V motors and it would be handy if they could be fitted side by side in an aluminium case. I’m planning on mounting them side-by-side, so that the power leads are as far apart as possible, and then reversing the current in one in software so that they give the expected results.

Is there likely to be any cross talk between them ?


#2

Hello.

Allegro does not list a separation distance for the sensors, but in the “Common Operating Characteristics” table on page 4 of the datasheet for the ACS714, they provide a “Magnetic Coupling” value of 12 Gauss per Amp. You might use a calculator like this to help determine an appropriate separation distance for your application.

-Nathan


#3

Thanks Nathan. If I’m driving that right, 12G equates 30A at 5mm. I’m looking at a separation of around 50mm.

I’ve also found a design note about shielding which includes this graph:

http://www.allegromicro.com/~/media/Images/Design/Managing-External-Magnetic-Field-Interference/fig4b.ashx?w=192&h=114&as=1&la=ja-JP

which shows that 1 trace carrying 50A at a distance of 10mm creates negligible offset in the sensor. It also recommends ensuring that cables carrying current near the sensor are routed perpendicular to the Hall element plane, so that gives me a good guide as to how to wire the parts inside the box I wll be using.