something betterthan ULN2803


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  1. #1

    Default something betterthan ULN2803

    I would like to switch 52v. To be safe I would like to know if there is any ic in the market like ULN2803 which can switch up to 60v (to be safe) and have ideally same or more channels on it. Thanks
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  2. #2
    Join Date
    Oct 2005
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    Sweden
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    Default Re: something betterthan ULN2803

    Hi,
    How much current are you switching?

    There's the SN75468/9 which is 100V, 500mA but only 7 channels.
    ULN2065 or STA473A might both be worth a look as well but is only 4 channels.
    HV5122 is a 32 channel, 200V device but only 100mA (and not 100mA thru all channels at once) and it's serial input.

    Then of course you could do with discrete logic level MOSFETs.

    /Henrik.

  3. #3
    Join Date
    Apr 2011
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    Welches, Oregon
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    195

    Default Re: something betterthan ULN2803

    I think that a multi-channel chip is fine for low amperage applications, but heat dissipation becomes the problem as power increases. For higher (but still modest) amperage loads, I use a Darlington - the TIP120 will switch 60 Volts, TIP121 80V, and the '122 100V - all at 5 amps. Henrik's suggestion of MOSFETs is a more educated suggestion, but I don't do much with high voltage/ amperage and have had good results with the 120. Physically separating them from the rest of the circuit and adding a heat sink to the 220 package is both simple and effective - for me.

  4. #4
    Join Date
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    Default Re: something betterthan ULN2803

    Depends what you're switching too. If there's any sort of coil/motor, current can be much higher on start-up.

    Robert

  5. #5
    Join Date
    Nov 2003
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    98

    Default Re: something betterthan ULN2803

    i haven't used BJT's for ages, i would go with discrete mosfets as there is virtually no static gate drive current requirement (dynamic is another issue) and modern mosfets have near zero conduction losses, darlingtons have around 1V Vsat or worse which is why you need a heat sink not to mention losing that valuable volt across the load,
    a few Amps w/ RDSon in the tens of milliOhms hardly requires a heat sink at all, just a flea spec on your board might do it

    additionally you often do not need the base resistors for gate drive

    what exactly is your load and switching speed ? and number of channels ? and operating voltage for what is presumably a PIC driving these ?

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