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TPL7407LA : I2C open drain expander at 24V

Robert Wood
Intellectual 420 points
Other Parts Discussed in Thread: TPL7407LA, TPIC2810

Hi,

I'm looking for a device that is controlled with I2C that would give sixteen open drain MOSFET outputs where I can sink a small current into the output MOSFETS (30uA) via a resistor. The resistors are supplied by a constant current source, but at 24V. So I'd being going 24V -> High Side Constant Current Source -> Resistor -> Open Drain output of expander.

I have found several devices, but they all seem to have a low maximum output voltage. TLP9202 looks close, but is SPI. TPL7407LA looks like it would do if it was I2C controlled and have four address bits so I could have enough 8-bit devices on the board. So, I think the perfect device would be a sixteen bit TPL7407LA controlled by I2C.

I did look at LED drivers, but they are seem to have constant current drivers built into them and that's no good for this application. I suspect if there was an LED driver that was simply switching on and off, that would be cool.

Thanks!

Rob

  • 0
    TI__Genius 16145 points

    Hi Rob, 

    We do not have a solution like you are describing in our low side switch portfolio. 

    Best Regards, 

    Elizabeth 

  • 0 in reply to Elizabeth Higgins
    Intellectual 420 points

    Hi,

    Was looking for an alternative way to save PCB space and once again Googled ULN2803 FET equivalent and came across a discussion where someone mentioned TPIC2810.

    This looks to be almost exactly what I want. OK, I'll need an I2C multiplexer, but that's a minor inconvenience.

    Am I missing something here? Why did you not mention this?

    Thanks! :)

  • 0 in reply to Robert Wood
    TI__Genius 16145 points

    Hi Robert, 

    Unfortunately I cannot provide the best support on the TPIC2810 as it is not part of the Load switch/PMUX portfolio, but great to hear that will work well for your system! If you have any further questions on this part, please reach out to the BU in question by typing the part number in the e2e thread and this will give you more accurate support on this part.

    Best Regards, 

    Elizabeth 

  • 0 in reply to Elizabeth Higgins
    Intellectual 420 points

    OK, thanks for the reply.

    One thing I will say (in an attempt at some constructive criticism) - and I suspect you're going to say this isn't part of your remit - but your website is absolutely rubbish for finding parts.  I had trawled through the LED driver looking for something just like this and nothing came up. I only found it because someone on a forum mentioned it.


    There are two points I think:

    1. I know that you have an algorithm for hiding older parts in an attempt to push people to designing in newer parts, I think that is a terrible idea.
    2. Your parametric search (once you have fixed point 1, because if you still hide older parts then a better parametric search won't help) needs a big overhaul.

    Thanks again.

    Rob

  • 0 in reply to Robert Wood
    TI__Genius 16145 points

    Hi Robert, 

    Thank you for your constructive criticism. 

    Understood finding the right part can be frustrating, so we want to make it as easy for our customers as possible to find the right part for their system.

    Best Regards, 

    Elizabeth