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Original question:

TPS2663: Disconnect the GND side of the reverse polarity protection

TPS2663:Disconnect the GND side of the reverse polarity protection(2)

user1238011
Prodigy 115 points
Part Number: TPS2663

Tool/software:

This will be an additional question.
When using the MPQ5850 made by another company, MPS, with the power supply connected in reverse,(Fig.1)
a problem occurred in which the power supply on the load side was turned on via the GND=>FET=>SW path (Figure 1).
This is because the correct potential is generated between the power supply's FG and the load's "+".
The cause of the problem with the MPQ5850 can be identified using the equivalent circuit, but not with the TPS26631PWPR equivalent circuit.
Q1.Does the TPS26631PWPR have such a current path? (Fig.2)
Q2.Does the FET have a diode so there is a path for current to flow? (Fig.2 Route2)

*The datasheet states that the MPQ5850 also has reverse polarity protection.

Fig.1

Fig.2

  • 0
    TI__Mastermind 30701 points

    Hello,

    I will check this and get back.

    Thanks

    Amrit

  • 0 in reply to Amrit Jit
    Prodigy 115 points

    It will be additional information.
    Operation was confirmed using the TPS26630-33EVM.
    When using the TPS26630RGER circuit and reversing the power supply connection as shown in Figure 3, voltage was confirmed at RL.
    The circuit currently under consideration is shown in Figure 4, but based on the results of Figure 3, a voltage is applied to RL.
    So I'm thinking of using the circuit in Figure 5, but will there be any problems?

    Figure 3

    Figure 4

    Figure 5

  • 0 in reply to user1238011
    Prodigy 115 points

    The jumpers on the TPS26630-33EVM are as follows.
    J1:OPEN
    J2:OPEN
    J3:OPEN
    J4:6.0A
    J5:OPEN
    J6:OPEN

  • 0 in reply to user1238011
    Prodigy 115 points

    Additional information on the evaluation board for the experiment in Figure 3
    I found that current was flowing in the forward direction of D4, so I removed D4 and C3, but voltage was still applied.
    I also checked with VIN=10V, I=2A, but when I removed D4, it became about 1.3A.

  • 0 in reply to user1238011
    TI__Mastermind 30701 points

    Hello,

    What's the voltage you are seeing on VOUT?

    On application of reverse polarity, External blocking FET will be OFF, and path will be open. So, No current will flow because path is open.

    You can see some voltage on VOUT because it's floating. 

    Can I understand what your application what you are trying to achieve? 

    Thanks 

    Amrit 

  • 0 in reply to Amrit Jit
    Prodigy 115 points

    Thank you for your answer.
    VOUT is 9.9V.
    RL is actually a DC/DC converter or IC, and its GND is connected to FG via R1 (Figure 4).
    In terms of realizing this in an application, when the power supply is connected in reverse in Figure 4,
    we do not want power to be applied to RL and the IC to operate, but from the experiment in Figure 3 it can be assumed that power will be applied to RL and the IC will operate.
    Therefore, we believe that the problem can be solved by using the circuit in Figure 5.

  • +1 in reply to user1238011
    TI__Mastermind 30701 points

    Yeah, Figure-5 would completely isolate the GND from supply.

    I don't see any issue in eFuse point of view with figure-5 toplogy.

    Thanks 

    Amrit 

  • 0 in reply to Amrit Jit
    Prodigy 115 points

    Thank you for your reply.