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OPA2196: Used as digital output

Jiri S
Prodigy 60 points
Part Number: OPA2196
Other Parts Discussed in Thread: TLV1811, UCC27531, TLV1805, OPA2991

We need to solve industrial digital output:

- Spuuly voltage:VDC: 12 - 30.

- Output: Low: 0 – 3 V, High: VDC – (VDC - 2 V).

- Input: Low: 0 V, High: 3.3 V (MCU).

- Operating output current up to 10 mA.

- Push-pull.

- Short resistant to GND or to VCC, continuous, auto recovery.

- Slew rate: 0.5 - 5 V/us. (Reduced edge speed for lower reflections and crosstalk on 200 m cable). Maximum data rate: 10000 baud.

- ESD (EN 61000-4-2) and EFT (EN 61000-4-5) protection.

 

Now we have following solution (VIO = 10 – 30 V):


 

But we registered several burnouts of OPA2196 during product assembly and testing.

I try to find solution. I found OPA2991QDGKRQ1 (slightly higher abs. max. voltage and better ESD protection). But I feel, there can be better solution.

 

Now we have new requirement: Short resistant to voltage level of 60 V (with auto recovery). Operating voltage remains 10 – 30 V.

 

I am considering to return to historical implementation:

... and to add source and sink current limit. Also change output FET to 60 V.

 

I can't use eFuse, eg. TPS26600, because there is too large turn on time, when driving UVLO or #SHDN pin.

 

Can you suggest better implementation, please?

  • 0
    TI__Genius 12245 points

    Hi Jin,

    Let me loop the comparator team to see if they have any high voltage, push/pull comparators that could work for this, maybe the new TLV1811 can work.  I don't think you'll find many outputs that are tolerant to 60 V but similar to what you did on the previous solution, I'm sure you can add components for protection. 

    Regards,
    Mike

  • 0
    Guru 275410 points

    Another method for high-voltage translation is a gate driver like the UCC27531. The drive strength is much larger than needed, but this allows you to add a series resistor to limit the current (which also makes external overvoltage and ESD protection easier).

  • 0 in reply to Clemens Ladisch
    TI__Mastermind 24330 points

    Jin

    Thanks for your post to the forum and thank you Mike for connecting us.

    As Clemens mentioned, you probably have some options but the one I was thinking of was our TLV1805.  This is a 40V, push pull output comparator.  This is used is several applications to convert low voltage logic signals to higher voltages as set by the positive supply voltage of the comparator.  I am not sure that I am completely understanding the requirement for short resistance to 60V.  I assume you mean that the output could accidentally get shorted to 60V.  Is that correct?  In that instance, you would need to have a series resistor between the TLV1805 comparator output pin and where the short to 60V can occur as to limit the current through the high side ESD protection diode.  It is not ideal to do this but this is what would be required to use our TLV1805.  Depending on how frequently this occurs and for how long, you could adjust the value of the series resistor.  I would recommend limiting the current to less than 1mA as a general rule of thumb as this will not damage the ESD diode.  So for a 30V operating voltage, that would mean placing a 30k resistor in series with the output.  This could slow down output rising and falling edges depending on the load capacitance.

    Hope this helps.

    Chuck

  • 0 in reply to Chuck Sins
    Prodigy 60 points

    The capacitance of 200 m long cable is up to 10 nF. 30k series resistor leads to huge time constant. In some applications this driver feeds multiple loads, up to 4. The capacitance may be 40 nF.

    I solved this issue with bunch of mosfets, current limiters, transils and other discrete parts.

    In the end I assume OPA2991 may be also used, with 3 pcs of transils and 2 pcs of reverse current protection diodes.