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ADS1258-EP: Internal Multiplexer ESD Diode Rating

John Guth
Prodigy 20 points

Part Number: ADS1258-EP
Other Parts Discussed in Thread: ADS1258,

To what ESD test levels are the multiplexer input protection diodes rated for on the ADS1258 converter? Alternatively are there safe operating area curves (power vs time) available for the protection diodes?

  • 0
    TI__Mastermind 44780 points

    Hi John,

    Welcome to the TI E2E Forums.

    Are you asking for the voltage level ratings for the HBM and CDM ESD tests?
    I've put in a request to our quality team to provide the results of these tests, and will let you know as soon I have this information.

    Please note that the internal ESD diodes are primarily intended for ESD protection during handing and end-equipment manufacturing. These types of electrical over-stresses tend to be lower overall power, single events (i.e. not an continuously applied over-voltage condition) that occur while the device is off. For higher power, in-circuit ESD protection from over-voltages external ESD protection circuitry should be used. In the Absolute Maximum Ratings table of the datasheet, we do specify an allowed continuous 10-mA current limit which means that the internal ESD diodes can tolerate over-voltage conditions without degrading the device reliability so long as external circuitry limits the input current to the device to 10 mA or less.

  • 0 in reply to Christopher Hall
    Prodigy 20 points

    Thank you for your quick response on this Chris.  Until your response, I wasn't 100% sure that the 10 mA absolute max rating on inputs was due to the ESD diode's clamping current rating.  I wondered if that 10 mA was intended to be the limit the current draw on the input of an external conditioning stage between the MUX outputs and the A/D inputs. For example, if my external conditioning input stage impedance was 500 ohm or less for a 5V max A/D input, I'd exceed the input rating.

    If you happen to have details of the ESD model and voltage levels that the diodes are tested to, I would be interested, but I was mainly trying to determine the diode robustness.  In my design, under power up and power down conditions and during input transients, the current will be limited to less than 1 mA peak.  I wanted to be sure this wouldn't be destructive.

    Regards.

    John 

  • 0 in reply to John Guth
    TI__Mastermind 44780 points

    Hi John,

    FYI: The ADS1258-EP was tested for a minimum 2 kV HBM and 500 V CDM. Unfortunately, I didn't find much data with the results for each package type, but my best guess is that each package probably passed the above minimum ratings as that was a standard criteria at that time.

    If you're limiting the over-voltage input current to the device to 1 mA peak then you're well below the absolute maximum ratings and should be fine.