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TPS2660: TPS26602 overload response time and OVP connection

Yunjing Wang1
Expert 4280 points
Part Number: TPS2660

Hi Team, 

My customer is using TPS26602 and have 2 questions.

1.Overload response time

Customer is using Active current limiting mode, want to make sure it can pass a ms-time overload caused by Hotswap, and need our test data.

Refer to datasheet,   

In Electronic circuit breaker mode, when the I(load)>I(CB) longer than 4ms, the device turns OFF the internal FET and FLT is asserted.

In Active current limiting mode,  the internal FET is turn off until the device junction temperature reaches the thermal shutdown threshold (T(TSD)).

 

Is the time to reach the shutdown threshold in Active current limiting mode much longer than 4ms t(CB)_delay in Electronic circuit breaker mode or not?

Do we have related test result show specific response time in active limiting mode?

2.OVP Pin connection.

Refer to the datasheet, TPS26602 OVP pin must connect to RTN directly, but they connected as resistor divider like TPS26600 application circuit in datasheet. However, it turns out that TPS26602 can clamp at 38V in input overvoltage.

Is it OK to connect resistor between OVP and RTN pin for TPS26602? Is there any potential risk to do as this?

Thank you!

Yunjing

  • 0
    TI__Guru** 105361 points

    Hi Yunjing,

    1. In Active current limiting mode,  the internal FET may serve more than 4ms but again it depends on the power dissipation across the FET, board layout and ambient conditions. 

    In current limit mode, the device maintains constant current value which was set at Rilim. The power dissipation across the device in current limit mode is (VIN-VOUT)*I_limit. This power dissipation causes the device junction temperature to rise and device latch-off when it hits thermal shutdown temperature. As you see, higher the OC threshold (I_limit), lower will be the time the device takes to hit thermal shutdown.

    2. OVP pin must be connected to RTN directly for overvoltage clamp response. A resistor can be connected between OVP and RTN but ensure the drop across the resistor to be less than 180mV which is the Internal OVP select threshold V(SEL_OVP)

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    TI__Expert 4280 points

    Hi Rakesh,

    Thanks for your reply.

    Is there any test data about the response time for Active current limiting mode and  Electronic circuit breaker mode? If yes, can you share to me through email?

    Also, is it possible for TPS26602 to control the overload response time by external RC component?

    Thanks & Best regards 

    Yunjing

  • 0 in reply to Yunjing Wang1
    TI__Guru** 105361 points

    Hi Yunjing,

    The typical response time is 30us for Active current limiting and Electronic circuit breaker but we have not characterized those parameters.

    Also, is it possible for TPS26602 to control the overload response time by external RC component?

    No. Can you let us know why we need control on the overload response time ?

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    TI__Guru** 105361 points

    Hi Yunjing,

    I have received your email with some more details on the requirement. I will get back to you early next week on email.

    I am closing the thread here.

    Best Regards, Rakesh