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OPA187: Differential Input Absolute Maximum Rating

Shaked Shaked
Prodigy 20 points
Part Number: OPA187


Hi,

On the OPA187's datasheet revision of July 2017 it says in the absolute maximum rating section, that the differential input voltage should not exceed plus or minus 0.5V. if I understand correctly the reason for that is a pair of diodes connected between the two input pins.

On the revision currently available on the website is says no such thing, although that pair of diodes still appears to exist.

Can you explain why the latest version of the datasheet does not say anything about the differential input voltage?

Thanks,

Shaked

  • 0
    TI__Guru* 93105 points

    Hello Shaked,

    You have spotted an error with the current OPA187 datasheets. I have verified there is an error with the signal input voltage Absolute Maximum rating listed in Table 6.1. Figure 39 in the datasheet shows why the absolute maximum differential voltage cannot be (V-) -0.5 V Min, or (V+) + 0.5  V Max. There are back-back clamping diodes across the OPA187 inputs that will limit the maximum differential voltage to about +/-0.5 V.

    The Systems Engineer is now aware of the problem and he indicated that the absolute maximum signal input voltage will be corrected in the next OPA187 datasheet revision. Use +/-0.5 V as the maximum differential input voltage.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    Guru 48395 points

    And that is about what you would get if you overdrove it due to the diodes, however, the real issue is the allowed current in what will be limited to those diode voltages. The external R's will set that current along with the overdrive voltage, but can they handle 10mA, 20mA, 100mA before damage?

  • 0 in reply to Michael Steffes
    TI__Guru* 93105 points

    Hi Michael,

    The various OPA187 input diodes are specified with a maximum forward current of 10 mA.

    Regards, Thomas

    Precision Amplifiers Applications Engineering