Sink & Source Driver ICs - Current Limits & Replacements

Discussion in 'General Electronics Chat' started by elec_mech, Jun 18, 2012.

  1. elec_mech

    Thread Starter Senior Member

    Nov 12, 2008
    1,513
    193
    All,

    I'm using a ULN2004 and UDN2981/2 IC in a couple of LED circuits to sink and source, respectively. The ratings on both of these ICs is 50V, 500mA per output pin. Is it safe/smart to use these ICs in applications requiring close to 500mA, say 450mA?

    Per SgtWookie, I know while a standard transistor like a 2N3906 is rated up to 200mA, it's best not to put more than half of that (100mA) through it. Should this same derating safety factor (~50%) be used for driver ICs as well, specifically the ULN and UDN families?

    If not, can anyone recommend other ICs that can sink/source 450mA safely? I know I can use individual transistors or MOSFETs with higher ratings, but I'm trying to conserve board space.

    On another note, the UDN2981/2 has been my favorite source IC for some time, unfortunately these appear to be discontinued. I found this as a replacement: http://www.toshiba.com/taec/components2/Datasheet_Sync//393/8992.pdf. Any reason these won't work the same as the UDN2981/2? Just looking for another readily available source IC.

    Any advice is appreciated. Thank you in advance.
     
  2. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    If you have doubts about this, I suggest to cool these ULN ICs, maybe using a cooling grid for 4 ICs together.

    Do you talk about SMD digital MOSFETs? I know one that can handle 2 Amps:

    The TMS2302, and Radionics has these for good price.

    8x of these = not much larger than a DIL IC.

    LEDs are not critical = static loads, small bulbs or motors are different, inrush current = higher.

    Important = to keep IC temperature less than 80C.

    For myself I consider any component that is uncanny to touch = too hot, needs cooling, or change to different component.
     
Loading...