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Original question:

PGA281: PGA power sequencing

PGA281: PGA281 power supply sequence

Yunjing Wang1
Intellectual 2770 points
Part Number: PGA281

Hi team,

My customer is using PGA281, but can you help clarify the power sequence requirement of PGA281? 

I see your answer in below thread said that datasheet page 20 describes the power sequence, but we only find below information, did not say specific requirements of power sequence.

"VSOP can be turned on first or can be higher than VSP without harm, but operation fails if VSP and VSN are not present."

https://e2e.ti.com/support/amplifiers/f/14/t/768794?tisearch=e2e-sitesearch&keymatch=PGA281%252525252525252520supply

Thank you in advance!

Best regards!

Yunjing

  • 0
    TI__Mastermind 49405 points

    Hi Yunjing,

    The limits of the Absolute Maximum Ratings of page 2 must not be exceeded at any point in time.   For example, an input signal must not exceed the supply by VSP+0.5 or VSN-0.5V, or in other words, the user must turn on the supplies prior applying the input signal. 

    However, beyond the limits listed on the Absolute Maximum Ratings, and beyond the operational supply limits listed on the Electrical Characteristics Table on page 5, there are no strict power-supply sequence order requirements for the PGA281. As page 20 of the datasheet mentions, the maximum supply voltage between VSOP/VSON must be observed or externally clamped since it is not internally limited.

    Do you have a specific question about the PGA281 Power supply requirement?

    Thank you  and Regards,

    Luis 

  • 0 in reply to Luis Chioye
    TI__Intellectual 2770 points

    Hi Luis,

    I just want to ask if PGA281 need specific power supply order and thanks for your detailed explanation.

    Best regards

    Yunjing

  • 0 in reply to Yunjing Wang1
    TI__Mastermind 49405 points

    Hi Yunjing,

    There are no strict power supply sequence requirements for the PGA281.  The main concern is to ensure that the Absolute Maximum Ratings are not exceeded at any point in time, and input signals must not exceed the supplies, or in other words, the user must turn on the supplies prior applying the input signal. If the device will see an input signal exceeding the supplies, an external protection clamp circuit is recommended.

    The operational voltage range for the power supplies is shown on the Electrical Characteristics table on page 5. 

    Thank you and Regards,

    Luis

  • 0 in reply to Luis Chioye
    TI__Intellectual 2770 points

    Luis,

    Understand and thank you!

    Best regards

    Yunjing

  • 0 in reply to Yunjing Wang1
    TI__Mastermind 49405 points

    Hi Yunging,

    One additional comment: it is always good practice to add external protection TVS diodes on each (VSN/VSP) supply to protect the device for over-voltage conditions or reverse supply conditions.  Also observe the maximum VSON/VSOP and DVDD supply rating since there is no internal protection; and may need to add external TVS diode protection to these supplies as well if there is risk that the device will be exposed to an over-voltage or reverse voltage conditions on those supplies as well.

    There is a generic TI Precision labs tutorial section that discuss the selection of the optimal TVS diodes for a given a supply/device specification that you may find useful:

    Thank you and Regards,

    Luis