Can I use a "Pre-FET" switch to drive loads directly?

Discussion in 'The Projects Forum' started by Beecher, Jun 15, 2009.

  1. Beecher

    Thread Starter New Member

    Jun 14, 2009
    Fellow Travelers:

    My application requires controlling a set of six 12VDC solenoid valves that each pull a 500mA holding current. Logic control is supplied by a PIC microprocessor sending a +5V signal to trigger the valve. No more than two valves are drawing current at the same time.

    The current design uses individual IPS1051L low-side power MOSFETs to handle the switching. However, I'd like to eliminate these individual components in a new design to save space and assembly time. My first impression was to use a Darlington array to replace the IPS1051L's, but the beefiest Darlington I can source is 500mA max per channel so I'd be living on the edge.

    Instead, I'm considering using a TI TPIC46L series low-side "pre-FET" driver to switch the valves directly (datasheet here:

    Although TI specs this chip for triggering external FETs it seems to have enough oomph to switch the valves directly. However, I'm skeptical that TI would call this a "pre-FET" driver if it could actually handle the kind of application I'm looking at.

    Am I missing something here? Does anybody see a problem with replacing the six IPS1051L's with one of these?

    Thanks in advance.
  2. mik3

    Senior Member

    Feb 4, 2008
    This chip is designed to drive FET transistors, thus you cannot use it to drive solenoids directly.
  3. Beecher

    Thread Starter New Member

    Jun 14, 2009

    Any particular reason why it would see a FET and another load differently?
  4. SgtWookie


    Jul 17, 2007
  5. Beecher

    Thread Starter New Member

    Jun 14, 2009
    Thanks Sarge.

    Missed that one when I was digging around for a higher current Darlington. That should do the trick nicely.

    Much obliged.