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OPA2192: Behavior at power OFF

Hiroshi Takahashi
Prodigy 210 points

Part Number: OPA2192

I have some question about  OPA2192.

In the situation the power of OPA 2192 is OFF.
How to prevent damage to the OPA 2192 when applying an external voltage to the output pin (pin 1) of the OPA 2192?
For data input pins on the data sheet, it is stated that the input current should be ±10 mA or less.
However, I could not find a description about output pins.
If the current of the output pin is suppressed to ± 10 mA or less,(Insert a resistor between output pin and external power supply)
Will OPA 2192 receive no damage?

Kind regards,

Taka
  • 0
    TI__Guru* 93105 points

    Hello Taka-san,

    The OPA2192 output pins have ESD protection diodes connected to each of the power supply pins as seen in datasheet Fig. 65. These diodes are identical to the input ESD diodes in terms of their electrical ratings; thus, their maximum continuous current is +/-10 mA. Adding an external series way is an effective method for limiting current.

    You don't mention if you are using a single, or dual supply. Let's assume for the moment that you are using a single V+ supply and the V- pin is connected to ground. If you apply a positive voltage to the output pin when the V+ supply is turned off and appears as a high impedance, then the upper output ESD diode can become forward biased and provide a path for current to the V+ pin. The OPA2192 will power up, but because the output ESD is being turned on the amplifier will not be in its normal linear operating mode. 

    If you are using dual supplies and V+ is being powered by the output ESD diode path and V- is floating, that could be a potentially bad condition. That current flowing through V+ won't have a return path through V- . That might lead to latch condition. It is recommended in that case to include the transient voltage suppressor (TVS) diodes shown from each supply pin to ground as seen in Fig. 65. In this case, the current originating into the V+ can flow to the V- pin and back to ground via the V- pin TVS diode which becomes forward biased. If you aren't expecting any transient voltages on the V+ and V- pins zener diodes could be substituted for the TVS diodes.

    Note that TI doesn't recommend applying voltages to operational amplifier pins when the device isn't powered as described or shown in the datasheet. Therefore, no assurances about electrical behaviors, or freedom from device damage can be made. The user assumes responsibility for the outcome. 

    Regards, Thomas

    Precision Amplifiers Applications Engineering