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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]
  • The MAX14912/13 have 8 output channels which are controlled (turned on or off) by either a SPI interface typically from a MCU or by pin control mode with input pins IN1-8 controlling the corresponding output channels OUT 1 -8. These products include a feature called SafeDeMag which automatically protects the outputs from overheating due to the inductive energy discharge - details are in this application note Switching Inductive Loads With Safe Demagnetization | Analog Devices Note that the max current limit per output channel is 1.2A. 

  • Hi Nianyu Jiang,

    The MAX14912/MAX14913 does not work well for your needs. First of all, the current through the one channel is limited to 0.64~1.2A. Second, you should use an external diode to demagnetize the inductor when the High Side switch is OFF. The internal SafeDemag circuit can be used for currents <600mA.
    I recommend the MAX14916 MAX14916-Compact Industrial Octal 1A/Quad 2A High-Side Switch with Diagnostics ( which has up to 2.4A driving capability when two channels are in parallel, but it still requires to use an external TVS as explained in the Application Information section.

    Best Regards,

    Yuriy Kurtsevoy

  • Another suggestion is to use a single channel high-side switch controller with current limiting MAX14922.pdf ( In this case, you should select the external sense resistor, MOSFET and TVS.

  • Hi YuriyK1,

    Thanks a lot for the detailed explain, and I have another question if you would like to provide any suggestion. 

    In my application, I may only pass 3A for a short pulse (~10ms) then switch it off for long period 100ms, and repeat the cycle multiple times. In this case, the average current amount is still low but the peak current will be high. Do you think MAX14916 can manage this? Or should I stop looking for high frequency switches and start looking for some current charging and firing circuit?

    Thanks for your time,

    Nianyu Jiang

  • In both cases, with the MAX14912 or MAX14916, the peak current of 3A exceeds the max current limits. The DO switch will/may go to thermal shutdown due to overheating. It is hard to predict when the thermal shutdown can occur because it also depends on ambient and die temperature. Is the peak current of 3A limited only by the coil impedance? How are you going (prefer) to control the switching frequency, using the SPI or input pin? How many DO channels do you need? 
    In any cases, the 3A of peak current will not break the part, but knowing application details allows suggesting a better solution. 

  • Hi YuriyK1,

    Thanks for the explain. This is an early study about generating magnetic field for an engineering project. We are ultimately trying to generate a 0.5T magnetic field using a coil (I am now using a adafruit electromagnet) with a on/off frequency at 10~1k Hz. 3A is the minimum current I calculated for the flux density, I may need to further increase the current up to 10A if necessary.

    I am not an expert at inductive load control and thats what I am trying to do: I prefer to use a PWM signal (input pin from microcontroller or wave generator), to switch on/off the device, which means I need at least a digital controlled switch and a inductive load driver with protection (correct me if I am wrong). We currently need only 1 channel but in future we aim at 6~8. I learned that switching inductive load (especially at high frequency) will need specific care for the reverse voltage when shut off and thats why I am trying to find a well-designed driving circuit.

    Based on the info, could you please give me some suggestions on what types of product should I aim for?

    Appreciate your time and help!

    Nianyu Jiang

  • Hi seanl,

    Thanks for the notification about the current limit.

    Nianyu Jiang

  • Okay, you are going to control the magnetic field by controlling time of the current flow (PWM) through the coil. In this case, the MAX14900E fits better for your purposes. You are going to use parallel mode to control the output(s) through the IN_ pins. You will be using the MAX14900E under short circuit conditions, but it is okay since this is an engineering project. The MAX14900E EVKIT (MAX14900DEVBRD) is available on the DigiKey website and it does not need any modifications. In high-side mode, multiple outputs can be connected together in parallel to achieve higher load currents. 

  • Hi Yuriy,

    Thanks for this suggestion! I will give a look at the datasheet and consider the 14900E.

    Appreciate your help so much!

    Nianyu Jiang

  • Hi Yuriy,

    Thanks for the information, the MAX14900E looks exactly what I need for a quick setup and project test. I have one more question by reviewing the datasheet. Suppose I am using the parallel mode by combining 4 output, does the current limit simply increase 4 times? or it can be calculated by some equations?

    Nianyu Jiang