LTC4013 TVS Diode

On page 23 of the datasheet it states:

If the input
voltage is more than the gate breakdown of the external
transistor, a TVS diode is required to prevent the disable
current or pin leakage from pulling INFET all the way to
ground.

No problem.  But on page 35, the schematic shows the symbol for a bidirectional TVS (D4).  It also states D4's part number is CMDZZ5245B which is a simple Zener, not a bidirectional TVS...  

I assume a Zener or unidirectional TVS will be fine?  Or should a bidirectional TVS be used as the schematic symbol suggests?

Thanks!

Chris

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  • +1
    •  Analog Employees 
    on Dec 6, 2019 4:20 PM

    Hi Chris,

    Good catch. We recommend a bidirectional TVS. In the case where you have two FETs installed on INFET (the blocking FET required for MPPT), you can use a Zener (as is done on the demo board).

    Regards,

    Zack

  • What are the recommendations to select a good TVS diode? Vbr(tvs) < Vgmax(mosfet) ?

    I am using the LTC4359 ideal diode to block the surge current (as detailed page 35, fig. 20 or the LTC4013 datasheet). If this device is blocking the current flowing from the battery to the charger, so M1/D4 are useless?

    Regards

  • 0
    •  Analog Employees 
    on Aug 19, 2021 1:30 AM in reply to bonelli

    Hi bonelli,

    Hope you are doing well.

    That is correct. The breakdown voltage of the should be less than abs max of the gate to source voltage of the mosfet.

    Can you elaborate your question about the use of the LTC4359 please? from my understanding, the application presented on figure 20 using the mosfets (with the gate drive provided by the INFET) will act as an ideal diode as well so I don't see why you need to use the LTC4359 for it. So in this case, the M1/D4 will be at used.

    Regards,

    Siglo

Reply
  • 0
    •  Analog Employees 
    on Aug 19, 2021 1:30 AM in reply to bonelli

    Hi bonelli,

    Hope you are doing well.

    That is correct. The breakdown voltage of the should be less than abs max of the gate to source voltage of the mosfet.

    Can you elaborate your question about the use of the LTC4359 please? from my understanding, the application presented on figure 20 using the mosfets (with the gate drive provided by the INFET) will act as an ideal diode as well so I don't see why you need to use the LTC4359 for it. So in this case, the M1/D4 will be at used.

    Regards,

    Siglo

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