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TLV274: AOP TLV274 use to rectify an AC signal troubleshooting

ZODIAC AEROSPACE
Prodigy 60 points
Part Number: TLV274

Hello,
In my design, I used an AOP TLV274 to rectify an AC signal. I meet this problem in some cases, the first amplifier of the package is destroyed. I don't understand why?
A single supply of 14V is used to supply the amplifier package and the positive input of the amplifier is protected by a low leakage diode BAV199W.
Could you tell me what happen when the voltage on positive input is equal to (-0.9V) or  (VDD  0.9V)

 

  • 0
    TI__Guru**** 152026 points

    Zodiac,

    I prefer to look at input current. The absolute maximum input current is +/-10mA. This equals -22V to 36V at the CT_PHASE_C node assuming no current flows through the BAV199M diodes. Therefore I don't believe long duration low voltage (<+/-100V) is causing the damage. Does the CT_PHASE_C node go to a connector or to a galvanic barrier? If yes, then I suspect ESD event at connector or across galvanic barrier.

    Why did you ask about 900mV? Was this value chosen for a reason?

  • 0 in reply to Ron Michallick
    Prodigy 60 points

    Hello RON,

    Sorry for the delayed answer. I ask about 900mV because it's the maximum direct voltage of the diode BAV199M. One of my hypothesis to damage the AOP, it is that for any reason these diodes are entered in conduction and theirs forward voltage is applied on the negative input of the AOP. In some temperature conditions this forward voltage is below the absolute rating of TI secomductor and I don't know what is the happen in this case.

    My input CT_PHASE_C is connected to a current transformer through a connector.  

    Do you know what level of ESD can induce this type of damage? I ask about this because, I have already done some ESD tests. I didn't have the same default. In my test the four AOP are destroyed, whereas in my application only the AOP used for the rectifier is damaged.

    Regards,

    Denis

    Zodiacaerospace .

  • 0 in reply to ZODIAC AEROSPACE
    TI__Guru**** 152026 points

    Zodiacaerospace,

    In the normal damage, you said first amplifier is bad. In what way is it bad; shorted inputs or just wrong output?

    In the ESD test damage, you said all amplifiers are bad. In what way is it bad; shorted inputs, wrong output, or very high ICC?

    For ESD testing, I suggest connecting a CT to the input with an open wire running through the CT. Then I would apply ESD to the open wire. This setup is closest to the suspected normal world damage case. Be sure that amplifer power has a path to ground during the test. 

    The voltage level needed depends on the breakdown voltage of the current transformer.