• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Answers 1 answer
  • Subscribers 48 subscribers
  • Views 488 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

OPA1622: I connected pin 3 (GND) to V-(-12V) instead of GND.

user6365974
Prodigy 210 points
Part Number: OPA1622

I connected pin 8 (EN) of OPA1622 to V+ (+12V), pin 3 (GND) to V- (-12V) instead of GND, and connected the other pins as specified and continued to use them.

If so, what are the possible inconveniences?

  • 0
    TI__Guru 64950 points

    User6365974,

    You do not specify what are your power supply rails, (V-) and (V+)?  The OPA1622 GND (pin 3) is the reference voltage for Enable function (pin 8) and thus MUST be connected to a voltage between (V-) and (V+).  You may NOT connect pin 8 to 12V above (V+) or pin 3 to 12V below (V-) because this would forward bias ESD1 or ESD2 protection diodes, respectively - see below.  Also, doing so without limiting the current through ESD protection diodes to less than 10mA would damage the part.

  • 0 in reply to Marek Lis
    Prodigy 210 points

    The power supplies are V+ = +12V, V- = -12V. That is, V-= GND = -12V condition.

    It doesn't seem to damage the ESD protection diode.

  • 0 in reply to user6365974
    TI__Guru 64950 points

    GND in OPA1622 shown above is the reference voltage for enable pin, EN.  GND may be connected anywhere between (V-) and (V+)-1V.  The enable pin of the OPA1622 is used to toggle the amplifier enabled and disabled states. The logic levels defining these two states are: VEN ≤ 0.78 V (shutdown mode), and VEN ≥ 0.82 V (enabled). These threshold levels are referenced to the device ground pin, GND. The enable pin can be driven by a GPIO pin from the system controller, discrete logic gates, or can be connected directly to the V+ supply. Do not leave the enable pin floating because the amplifier is prevented from being enabled. Likewise, do not place GPIO pins used to control the enable pin in a high-impedance state because this placement also prevents the amplifier from being enabled.

    All in all, your connections of GND=(V-) and EN=(V+) are fine and should work with no issues.

  • 0 in reply to Marek Lis
    Prodigy 210 points

    thank you for your reply.
    No issues with the device so far.

    >GND in OPA1622 shown above is the reference voltage for enable pin, EN.
    >GND may be connected anywhere between (V-) and (V+)-1V.
    1.Is it correct to assume that using pin 3 (GND) in the range from V+ to V- is within the specifications?
    2. There is an explanation in the data sheet that the GND pin is the reference for the phase compensation capacitor, but is there any effect on this?
    (The device does not oscillate, so I think there is no effect)
    3. Am I correct in assuming that connecting the GND pin to V- will have little effect on the performance of the device?

  • 0 in reply to user6365974
    TI__Guru 64950 points

    1.  GND pin cannot be connected above (V+)-1V because this would make it impossible to enable the part.

    2.  I'm not sure of the question

    3.  It makes no difference on performance where you connect the GND pin for as long as it is between (V-) and (V+)-1V.

  • 0 in reply to Marek Lis
    Prodigy 210 points

    >2. I'm not sure of the question
    In datasheet 7.3.4 of OPA1622 there is an explanation about AC-PSRR.We have asked if there is any impact.
    (Ignore the issue of oscillation)

  • +1 in reply to user6365974
    TI__Genius 12955 points

    User6365974,

    Yes it is correct that the compensation capacitors are connected to "GND".  On many amplifiers, they are connected to the positive or negative supply.  For this device, since there is a GND node, it was used for the compensation capacitors.  For this reason, you should ensure the GND node is low impedance, not simply a resistor divider or high-impedance connection derived from the supply voltages.  Assuming that is the case, the voltage should not matter, as Marek mentioned in the post above.

    Let me know if there's any other questions.

    Regards,
    Mike

  • +1 in reply to Michael Hartshorne
    Prodigy 210 points

    Thank you for answering my question.