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bq24650 / removing the D1

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: BQ24650, LM5050-1, LM5050-2
Hello,
 
Our customer uses bq24650 under the output conditions of 13V, 10A.
Since D1 of reverse voltage protection has big power dissipation in this case, they would like to remove the D1 from their board.
Can we remove the D1 ?
 
Best Regards,
Ryuji Asaka
  • 0
    TI__Genius 13700 points

    Hello Ryuji,

    They could use a high-side P-FET like what is seen in Figure 3 of the App Note here: http://www.ti.com/lit/an/slva139/slva139.pdf

    This will give them reverse voltage protection and improve the high current efficiency.

    They may need to be careful of the Vgs limitations are adjust the circuit accordingly

  • 0 in reply to Ryan May
    Guru 20090 points
    Hello Ryan san,
     
    Thank you for the information.
    However I think that this application can't prevent reverse current protection at the condition of Vin(Solar cell) < Battery Pack.
    Could you please let me know other application?
     
    And in our customer, bq24650 on the bq24650EVM temperature was dropped when D1 was removed.
    Do you have any idea for this behavior that share with us? 
     
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Genius 13700 points

    Hello Ryuji-san,

    I will have to think about want can be done for the reverse protection case.

    When you say that the temperature has dropped does this mean that the temperature of the die is lower without D1 or the temperature sense feature is no longer working.

    If it is the first case looking at the EVM layout the proximity of D1 would make me think that be removing it and the losses associated with it there is less heat dissipated into the board which is results in a lower die temperature for the BQ24650.

  • 0 in reply to Ryan May
    Guru 20090 points
    Hello Ryan san,
     
    Thank you for the reply.
    I'm waiting the application for the reverse protection.
     
    Temperature mean is case temp of the bq24650.
    Case temp difference is over 5 degree between with D1 and without D1.
    I already informed that this is occured by difference of the heat dissipation from D1 on the board.
     
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Genius 13700 points

    Hello Ryuji san,

    I am glad that you the reason for the temperature difference has been cleared up.

    Have you looked into ORing FET controllers such as the LM5050-1 or LM5050-2? It will allow the current to conduct through the high side FET and it has reverse current protection to address the cases when the battery voltage is greater than the panel voltage.

  • 0 in reply to Ryan May
    Guru 20090 points

    Hello Ryan san,

    Thank you for the information.
    I introduced LM5050-1 to our customer.
     
    Best Regards,
    Ryuji Asaka