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  • TI Thinks Resolved

DRV110EVM: Help activating and controlling solenoid

Prodigy 10 points

Replies: 4

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Part Number: DRV110EVM

I am using a DRV110EVM board to energize a 24V solenoid to drive a cold gas thruster. 

Settings:

-JP1, JP2, JP3 close, JP4-9 open

-Pot R4, R5, R6  fully CCW

-Pot R3  fully CW

-24 VDC supply connected to P1-1 and P1-3

-Solenoid coil connected to P1-2 & P1-4

Solenoid coil type: Parker 12W 24VDC coil, 48 Ohms

I am trying to trigger the coil by applying 5V to TP3 (EN) using the NI MyRio run by a LabVIEW program. I cannot get any solenoid activation from the MyRio. However, the solenoid does fire randomly when JP2 is removed. Also, we blew the Pot R3 with too much current so we cut the zener diode in order to bypass that issue. Any clues on why the solenoid is not being controlled by MyRio?

  • HI Jacey,

    I have notified our expert regarding this request. Please expect a response by July 11th.

    Regards,
    Aaron
  • I would recommend that you add some notes in the user guide for the EVM board to start up this board with the R3 pot fully CW (higher R) to limit the supply current, and to never try to operate at fully CCW.

    The user guide explicitly recommends starting with the R4,5,6 pots fully CCW, but nothing is said about R3.  For a new EVM user it would seem logical to set R3 CCW also, but that will destroy the pot, the zener and the DRV110 chip, if the supply voltage is above the D3 zener voltage (20V).

    This results in a buzzing or humming in the relay coil winding while attempting to command pulses using the ENABLE line, and other unexpected results due to the failed DRV110 chip.

  • Hi Jacey,

    Thanks for your question. I believe the issue has to do with the current limiting resistor (R3) and the current setting (R4 and R5).

    In general, the DRV110 requires the PEAK and HOLD currents to be set specific to the solenoid used. Because you are using a 24V, 48 Ohm solenoid, I suggest setting the PEAK current to 500mA. You can do this by setting R_PEAK (R4) to 120 kOhm. The hold current will then need to be set to keep the solenoid closed. If the solenoid does not remain closed with R_HOLD (R5) shorted (CCW), try setting R5 to 60 kOhm to achieve the maximum current of 150mA. If the solenoid still does not remain closed, then R_SENSE (R8) will need to be replaced with a smaller value to raise the hold current.

    The DRV110 has an internal Zener diode that clamps the VIN voltage at 15V. Thus, a current-limiting resistor on VIN must be carefully chosen to limit the current flowing into the DRV110. This is what R10 and R3 are for. D3 serves as additional protection in case R3 is improperly set. It sounds like R3 was shorted, causing high currents to flow into D3 and the DRV110. It is possible that the potentiometer, Zener diode, and DRV110 device were damaged because of this. I recommend replacing R3 with a 9 kOhm resistor (as recommended by Table 3 in the DRV110 datasheet). If the EVM does not work at this point, I would replace the DRV110 unit.

    JP2 must be connected for proper operation of the DRV110. R6 can remain fully CCW (shorted to GND).

    Please let me know if this solves your issue.

    Best,
    Grant
  • In reply to kenneth house:

    Hi Kenneth,

    Thank you for your valuable suggestion. I will look into updating the user's guide.

    If you have questions about your usage of the DRV110 device, please feel free to start a new thread.

    Best,
    Grant

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