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LSF0102 / Behavior at suppling only one Vref

S.Satoshi
Guru 21675 points

Hi,

Please let me ask few question for attached three cases.

  1. At the case A, is there a possibility of damage to Vref_A pin? And is there no output signal on Bn pin if there is input voltage on An?
  2. At the case B, is there a possibility of damage to Vref_B pin? And is there no output signal on Bn pin if there is input voltage on An? And also is there any voltage on Vref_A through Vref_B?
  3. At the case C, is there a possibility of damage to Vref_B pin? And is there no output signal on Bn pin if there is input voltage on An? And also is there any voltage on Vref_A through Vref_B?

Best Regards,

Sonoki / Japan Disty

  • 0
    TI__Mastermind 27045 points
    Hello Sonoki,

    I have notified the appropriate engineers with you question. They should respond as soon as they are available.
  • 0 in reply to aozer
    Guru 21675 points

    Hi, Aozer,

    Thank you for your support. I found the simplified internal circuit from this app note.

    From this simplified internal circuit, I try to lead to an answer to following my question.

    1. At the case A, is there a possibility of damage to Vref_A pin? And is there no output signal on Bn pin if there is input voltage on An? [Sonoki] Short current will be happened from Vref_A through Vref_B.
    2. At the case B, is there a possibility of damage to Vref_B pin? And is there no output signal on Bn pin if there is input voltage on An? And also is there any voltage on Vref_A through Vref_B? [Sonoki] 3.3V can be seen on Vref_A through from Vref_B.
    3. At the case C, is there a possibility of damage to Vref_B pin? And is there no output signal on Bn pin if there is input voltage on An? And also is there any voltage on Vref_A through Vref_B? [Sonoki] 3.3V can be seen on Vref_A through from Vref_B.

    Please see my additional comment and give your opinion.

    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Guru 59120 points
    Sonoki san ,

    1) The LSF is turned off by connecting Vrefb and En together. A /B sides will be isolated .
    2) Is there no 200Kohm resistor on the VrefB /En pins? VrefA will be Vrefb -Vt . improper operation of LSF.
    3) LSF turned off and A/B channels should be isolated .