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TPD2S017 max voltage rating, but max current?

bowerymarc
Expert 1935 points
Other Parts Discussed in Thread: TPD2S017

The TPD2S017 lists the absolute max Vio as 5V.  Is that for ANY amount of current flow?  This needs clarification, as this is a clamping device.  If one single overshoot event causes it to fail, what good is it?

I imagine the diodes in this thing are fairly hefty and thus should be able to sustain some current flow - it's current that heats up and damages the diodes, up until the avalanche voltage which is a pure voltage effect, and looks to be much larger anyhow.  I need something to characterize the device - current, wattage, energy, etc.  Like a normal switching diode data spec.

Thanks!

  • 0
    TI__Genius 12190 points

    The absolute maximum rating given in our data sheets is for a constant 5V DC. The pin in question is rated for +/-11kV when subjected to short transient bursts as outlined in IEC61000-4-2, or about 100 ns. The device is not intended to clamp a DC voltage above its absolute maximum rating. Such a device would add a capacitance too great for a high speed signal line. This device is designed to provide ESD protection to up to 4 hi-speed lines, VCC and GND. As such, these diodes are actually very small, for low capacitance addition to signal lines.

  • 0 in reply to Guy Yater
    Expert 1935 points

    I asked for specific numbers, can I get that please?

    I'll quote from http://www.ti.com/lit/an/slla305/slla305.pdf :

    Absolute Maximum Ratings and Electrical Characteristics
    The absolute maximum ratings table of the device must be reviewed carefully. ESD protectors are
    typically not designed to handle DC overstress and an excess voltage above the absolute maximum
    ratings will most likely trigger the ESD device.
    While short time pulses (0–300 ns) will not damage the protector; DC like stress (>1ms) will result in
    damage if no current limitation is provided (typically ≈500 mA). TI will provide information about the DC
    characteristic of the ESD protection devices upon customer request, but it is generally not recommended
    to use an ESD protector as a DC voltage limiter.

    I'd like the specific numbers for the device.

    The DC-like stress I'm looking at is 90uA sourced from 5.5-6VDC.

    Looking forward to specific numbers for the tpd2s017 in the response.  Thanks.

    Regards,
    Marc 

  • 0 in reply to bowerymarc
    TI__Genius 12190 points

    Marc,

    The requested information is in the data sheet already. At 25C the device can sustain 463.18 mW and at 70C it can sustain 254.75 mW. Since you are looking at no more than 0.54 mW there will be no problem.

  • 0 in reply to Guy Yater
    Expert 1935 points

    Of course I saw that and based my initial design on that info, but we had an instance of a diode failure (pin 6 became shorted to ground) and wanted to make sure there wasn't any other limitations.

    The app note states the steady-state current should be <500mA, but that app note is not specific to any one device.

    If the total package power (derated of course) is the only practical limitation for continuous current (subject of course to the rated breakdown voltages) then I'm satisfied with the answer.  Please verify.

    Thanks,

    Marc

  • 0 in reply to bowerymarc
    TI__Genius 12190 points

    Hi Marc,

    Yes, the total derated package power absolute maximum specification should be the only practical limitation. Please let me know if you have any questions regarding the reported failure on pin 6 (as a short to ground.) I would be interested to know the root cause of that.

    Regards,

  • 0 in reply to Guy Yater
    Expert 1935 points

    I'm not sure we can find the root cause. It was a field failure, and according to the report, the signal was unused, so the only thing going on should have been 90uA sourced from 5.5V.  Not only that but pin 6 was connected to pin 1(using the two channels in the device in parallel) and only that one failed.  If you have any suggestions to try or want the part sent to TI for analysis let me know.

    Thanks,

    Marc

  • 0 in reply to bowerymarc
    TI__Genius 12190 points

    Marc,

    Thanks for the information regarding the failure and your offer to send the failed unit back. I don't think we could learn anything substantive by failure analysis since we do not have a clear idea of the circumstances. Thanks for the offer though.

    Regards,