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# How to pick up a electromagnetic coil control board?

Category: Hardware
Product Number: MAX14912

Hi everyone,

Recently I was trying to control a electromagnetic coil. The inductance will be 50 uH and I are attempting to pass large amount of current (1 ~ 3 A) into the coil under a constant DC power source (12~36 V).

To switch between powering and de-powering Inductive Loads at a high frequency (> 1k Hz), and considering all the safety requirement, I am trying to use a well build drive circuit. I came to read about this product: MAX14912/MAX14913 (link at end) and I am not sure if this will meet my task. Can anyone give some suggestions of driving and controlling the inductive load based on my need?

Appreciate for all the read and suggestions,

Nianyu Jiang

moved and updated the category
[edited by: GenevaCooper at 6:30 PM (GMT -4) on 28 May 2023]
• Hi Nianyu Jiang,

The current limit is for channel bases, and it does not change. When you are paralleling the output channels, the current will be spread between them approximately evenly and that allow to drive a higher total current. However, the channel's impedance is not equal and if the current through the channel reaches the limit, that channel may shuts off due to channel thermal shutdown. This can lead to cascading shuts of other channels. You should carefully select the number of paralleled channels based on the total current.

Regards,

Yuriy

• Hi Yuriy,

I have got the MAX14900E at my hand and ready for test. To my best understanding, the current limit (2A) is per-channel. I was trying to use high-side mode and paralleled 4 output channel together under short circuit condition. The coil resistance is 10 Ohm, and I suppose if I use a power source of 20V, I create 2A at each channel. If I choose the set power source limit as +20V 8A, does it meet my requirement of passing the maximum current into the coil? I would like to figure this out before I maximize the current input.

Thanks,

Nianyu Jiang

• Hi Nianyu Jiang,

If the coil resistance is 10 Ohm and supply voltage is 20V, the max current through the coil is 2A total (not at each channel). In this case 8A supply current limit will never be reached and it is safe to use maximum current limit. Do I miss something? If you trying to reach total current of 8A, the coil resistance should be 20V/8A= 2.5Ohm or you can put 4 coils in parallel. I suggest starting with one coil and then increasing number of coils to reach maximum magnetic field power.

Regards,

Yuriy

• oh I think now I understand the parallel mode which is distributing current not voltage. Thanks for your explain! I will give a try first and then see if I can make any improvement.

Nianyu Jiang

• Hi Yuriy,

We have tested the board which works fine. The board has the maximum voltage supply of 36V, considering our circuits is of 12 Ohm resistance, the current is at maximum 3A.

The magnetic coil, under 3A current, reached the magnetic flux density at what we expected. However, we intend to safely operate the coil at higher current for our project purposes. We are trying to find a similar board which can allow 120V, 10A (roughly). Is there any product that you can suggest?

Thanks for your help!

Nianyu Jiang

• Hi Nianyu Jiang,

I'm glad that you are able to reach your goal using the MAX14900E evkit. Unfortunately, we don't have devices that can support 120V, 10A, and safety requirements. The maximum operating voltage for the DO family is 36V. You will need to design such circuitry using discrete components.

Best Regards,

Yuriy