H-bridge MOSFET help

Discussion in 'The Projects Forum' started by hhoncho, Apr 13, 2006.

  1. hhoncho

    Thread Starter Member

    Mar 18, 2006
    Hello people,

    I am constructing a circuit to drive a solenoid using an H-bridge arrangement and would like help in deciding on which MOSFETs to use.

    My solenoid is operating at quite a high current. It has a coil resistance of 7.5 ohms and my circuit is operating at 11V, so its a mighty 1.5A. I intend to drive the gates of the MOSFETS from 4000 series CMOS logic in a fashion similar to the circuit described here:


    I currently have these P types:


    and these N types:


    would any of these do the job? If not can you tell me what to get.

    I also intend to use a solenoid which draws 1A from this circuit in the future, will I need to change the mosfets for this purpose or can I just switch out the solenoid?

    One last thing, I do not know which pins correlate to the gate, drain and source on these chips (yup I am that clueless), referring to the chip from the top and with the dual pin connection on the left, which connection refers to the gate, drain and source on these things.


  2. beenthere

    Retired Moderator

    Apr 20, 2004

    Read the datasheets. Any device that is rated for voltage and current in excess of your needs should do the trick. The datasheets will also give the pinout. Use a hexfet good for double the voltage and four times the current to be safe. Hexfets are cheap, and they all look alike to the driver.

    One question, though - solenoids are unidirectional devices. Why are you going to the elaboration of an H bridge to drive one? A single hexfet as a current switch should suffice.
  3. hhoncho

    Thread Starter Member

    Mar 18, 2006
    Hi, thanks for the reply. I will take into consideration your comments regarding the rated voltage and current.

    I have read the datasheets. There is no pinout illustration on any of them as far as I can see. It does comment on the "dual drain" so I presume that the dual pin connector is the drain, but which of the other two pins are the gate and the source? The datasheets are linked on my first post if you want to take a look.

    My solenoid is of the magnetically latching type and as such is bi-directional, hence the need for the h-bridge.
  4. Papabravo


    Feb 24, 2006
    Be calm. In the days before the internet, manufacturers published large paper databooks. Since many parts had the same package they put things like pinouts in an appendix. If you note on one of your datasheets, it points to a page 1515, in an appendix which the folks at datasheet archive did not scan.

    In cases like this it is always a good idea to check the manufacturer's website. IR claims they are mostly done with the scanning of legacy datasheets, which include the pinout information. In the meantime I found this for you

    HD-1 Package Pinout

    Hope this helps
  5. hhoncho

    Thread Starter Member

    Mar 18, 2006
    Cheers muchely.