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ADS1282-SP: ABS Max input current

Part Number: ADS1282-SP
Other Parts Discussed in Thread: ADS1281

The ADS1282-SP ABS max specifications indicate "100mA momentary" and "10mA continuous" limits for input current.

1. What input current is this referring to? Avdd? Analog inputs? Digital inputs? what about AVSS?

2. Is this current specified into/out of any one pin at a time or is it for a group of pins?

3. The Power Supply Electrical characteristics indicate 11mA max for AVDD - How can the part be used in this mode if the ABS max is 10mA continuous?

4. What is meant by "momentary" and "continuous" in the context of the ABS max ratings?

This information is needed to perform a worst-case analysis stress analysis.

Thanks!

  • Hi Steve,

    Please see comments to your questions below embedded below.

    1. What input current is this referring to? Avdd? Analog inputs? Digital inputs? what about AVSS?
    [CY] The Absolute Maximum "Input Current" spec refers to the analog input pins AINP1, AINN1, AINP2, AINN2, VREFN, VREFP,CAPP, CAPN.

    2. Is this current specified into/out of any one pin at a time or is it for a group of pins?
    [CY] The current cannot exceed this value in either direction, into or out of the device pin. Each pin must remain under this limit for all time or there is a high probability of permanent damage to the device.

    3. The Power Supply Electrical characteristics indicate 11mA max for AVDD - How can the part be used in this mode if the ABS max is 10mA continuous?
    [CY] The analog supply current max spec of 11mA refers to when the device is operating under recommended operating conditions outlined in the Electrical Characteristics table. None of the Electrical Characteristics specs are guaranteed outside of these conditions such as those conditions described in the Absolute Maximum Ratings table. Proper functionality is not guaranteed if the device is exposed to a condition outside of the recommended operating conditions.

    4. What is meant by "momentary" and "continuous" in the context of the ABS max ratings?
    [CY] The following is a response from a previously answered E2E question on a similar device, ADS1281.

    (e2e.ti.com/.../2177056

    "The absolute maximum ratings for this device specifies that the input current should not exceed 10 mA continuous current or 100 mA momentary current; however, I'm not sure what characteristics qualified a "momentary" current. Operating above these limits, I wouldn't be able to say how it might degrade the device's lifetime.

    The input voltage can exceed AVDD + 0.1V , as long as the input current is limited. However, using a clamping (voltage limiting) diode and a series (current limiting) resistor together is usually very effective at protecting the device. I would recommend using the more conservative 10 mA specification for current limiting."

    Finally, another post on this topic for a different device defined momentary as 200ms. However, I cannot definitively the same is true for the ADS1282-SP as the ESD diodes and the metal hookup to them might be, and most likely is, different. The safest approach is to limit current to under 10mA for all time. If this is not possible, then worst case voltage and current waveforms versus time would be needed so that a closer analysis can be performed.

    Thanks
    Christian