Footprint for Allegro CT110FDV-ID6 current sensor?

Support Q&A
1

------Question for CT110FDV-ID6 Please Put your question below------
I have the footprint for the Allegro CT110FDV-ID6.
Here is a screenshot of it:
CT110FDV-ID6 Footprint snippy

However, when I look at the layout for the eval board, the footprint looks different than the one I got from Allegro. See screenshot below:

CT110FDV-ID6 eval board1
CT110FDV-ID6 eval board1597×707 78.9 KB

Is the footprint from Allegro correct?

Thank you.

2

Yes, I would go with the footprint from Allegro, it appears correct. If there is any doubt you can always check against the dimensions provided in the datasheet, snippets below:
image

image
image1008×468 38.8 KB

3

Thanks for looking into this right away.

From the evaluation board’s footprint, it looked like current flowed into one end of the CT110 and out the other.

In the Allegro footprint, the two current sense pads are combined into one.

It’s a little confusing, that’s all. Thanks again.

4

I see what you’re saying about the evaluation board layout vs. the datasheet. I’m going to field this one with our Product Management team for Allegro to see what they say. We’ll get back as soon as we have anything.

1 Like
5

The device has a TMR-type magnetic field sensor inside which detects the magnetic field of the current passing through the pad on the bottom of the device. The sensor can detect magnitude and polarity of the field, which can be used to resolve for current magnitude and direction.

All that matters is that the current pass through that pad. In either footprint shown above, the current will pass through that pad and allow the TMR sensor to get the reading, so it doesn’t matter, from a functionality standpoint, which layout is used. However, using the entire pad would seem to be the better design practice, as it provides more surface area for the CT110 to adhere to the circuit board, which should make it less likely to break off due to external stresses.

Here’s a useful image Allegro shows in one of their power points covering TMR current sensors:

image
image633×727 57.4 KB

Note the continuous current strip underneath the sensor.

6

David and Kristof,

Thanks for your responses.

I will utilize Allegro’s footprint.

Is there a 3d model that I can download for the component?

Regards

7

Hello NSL22,

I’m sorry, but we do not have a 3D model for the CT110 part.

8

No worries. I believe my coworker requested it from Allegro directly.
Thanks again.