• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 266 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TPS22930A: About control of EN pin

Tsukui Yusuke
Guru 21930 points
Part Number: TPS22930A

Hi,

Customer is trying to control the EN pin with an MCU.
When the initial power supply is turned on, TPS22930A starts first and then the MCU starts.
In the background, the EN pin of TPS22930A becomes Hi-Z before MCU control.

I understand that the output will be in an indefinite state.
Are there any other risks?
Customers are worried about IC failures and malfunctions due to EN becoming Hi-Z.

Best regards
Yusuke

  • 0
    TI__Mastermind 32650 points

    Hi Yusuke-san,

    We do not recommend any operation of the device with EN floating. This could result in unsupported behavior.

    I believe the easiest fix is to add a pull down resistor on the EN pin. This will keep the device disabled until the MCU is powered.

    Thanks,

    Shreyas

  • 0 in reply to Shreyas Dmello
    Guru 21930 points

    Hi Shreyas,

    Thank you for your response.
    Customers want to reduce the mounting area as much as possible.
    So they don't want to implement pull-down resistors.

    >This could result in unsupported behavior.
    Could you tell me the operation other than the output ON / OFF is not confirmed?
    I need to tell the customer exactly the risks of putting the EN pin in Hi-Z status.
    Please tell me a specific example of malfunction when the EN pin becomes Hi-Z while the VIN voltage is applied.

    Best regards
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 32650 points

    Yusuke-san,

    If the device is powered and the EN pin is floating, we cannot confirm if the device is ON or OFF.

    The device could also be partially ON. 

    This could result in an unsupported conduction path from VIN to VOUT. We do not test the device in this way and so it is possible that failures could occur. As mentioned in the datasheet, we don't support EN floating. It is recommended that a pull down resistor is used.

    Thanks,

    Shreyas

  • 0 in reply to Shreyas Dmello
    Guru 21930 points

    Hi Shreyas-san,

    Thank you for your support.

    >If the device is powered and the EN pin is floating, we cannot confirm if the device is ON or OFF.
    >The device could also be partially ON.

    Customers are prepared for VOUT to be ON or OFF indefinitely.
    What kind of unstable operation is confirmed when the internal circuit is partially turned on?
    Customer applications have a limited footprint and it is important to be able to reduce one pull-down resistor.
    Therefore, I need to clearly explain to the customer the disadvantages of the conduction path.

    Best regards
    Yusuke

  • +1 in reply to Tsukui Yusuke
    TI__Mastermind 32650 points

    Hi Yusuke-san,

    As mentioned there could be partially ON operation. We cannot confirm what will occur as this is not supported by TI and so all possibilities must be taken into account.

    Please let the customer know that we have explicitly stated in the datasheet that this operation is not recommended. 

    Thanks,

    Shreyas