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Most needed device in my entire career still doesn't seem to exist

D.W.
Prodigy 150 points
Other Parts Discussed in Thread: TLC5955, TLC59116

Most needed device in my entire career still doesn't seem to exist, but I could be wrong.


This situation keeps coming up, again and again. I have 20 LED's to drive (actually 40, but I have two common-cathod banks I can switch between with a couple of NPN transistors); but anyhow, I need 20 channels of source driving, from a 5V supply, 10mA per channel minimum, but preferably rated 20mA+ to be safe.

On the input side, however, I need either a serial interface, I2C or SPI, or 5-bit addres + data + latch, because I can't find a PIC microcontroller with enough i/o' that can drive so many channels PLUS all the other things I need the controller to interface with.

I've had this need, or a similar need, so many times during my 25-year career, and can never find a single part to do it. Always end up having to have two parts to do it: an addressable latch AND a driver, which is then problematic in terms of board-space. Actually, I do remember finding a combined solution about 10 years ago or so, but it was prohibitively expensive, --not suitable for a mass produced product.

But maybe my searching skills are the problem... (?)

So, my question is, is there such a thing (from TI or some other company)?

And if not, could it *finally* be made? It would be the hottest seller, I'm sure.

  • 0
    Prodigy 150 points
    I've actually switched to a larger controller; you can dismiss this post for now; but I do wish to reiterate this is a needed component.
  • 0 in reply to D.W.
    TI__Expert 3460 points

    D.W.

    Glad you found a solution. You can also look at the TLC5955 which has 48 channels. It operates through serial communication.

    The TLC59116 is only 16 channels, but it has I2C communication.

    Hope this helps.

  • 0 in reply to Harry Kennedy1
    Prodigy 150 points

    Thanks!

    That TLC59116 looks gorgeous; I may use it in the future; but a bit too many features for this app I'm working on (e.g. I don't need PWM), and 16 channels vs. 20 that I need; and then using two 59116's, or the 5955, is beyond our current budget. So, a bigger microcontroller will have to do for now.

    What I would say is still missing in the market, now that I saw these two devices' specs, if you care, is something like,

    Say 16, 24 and 32 ouput models of...

    Simple ON/OFF control for each LED (no PWM, but maybe a common dim control)

    I2C 2,3,4-byte control, each bit = 1 LED, (+ 1 byte dim) + 1 byte CRC.

    External resistor to set maximum current (at dim = 255).

    Address pins.

    Super-cheap ;-)