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TPS2662: current limit unexpected behaviour

Part Number: TPS2662

Hi Team, 

My customer encountered an unexpected behaviour for currentlimt function on TPS26625. 

He changed the RLim value from 30 kOhm (working setup) to 12kOhms set the current limit to 550mA. His testload is a potentiometer.

1 . At start-up: 31 ohm load connected to the output. Then 24V connected to the input. The current is limited to the 550mA. OK
2. During operation: The output is limited only when the load is equal to 31 ohms (approx. 760mA). This means: I can, for example, pull 700mA permanently. NOK
3 . During operation: After a fault, the current is no longer limited until 550mA.





  • Hi Jan,

    Thanks for reaching out!

    Is the Iout current you measured before the Cout or after the Cout. ? Can you please share a test waveform of Vin, Vout, Iout and FLT in one scope shot as point in below.

    Best Regards, 


  • Hi Rakesh,

    find attached the measurments of  I = current in front of the Cap, Cout, Vin, Vout and /FLT


    1. Current before Cout.
    2. Strom after Cout
    3. current limit (I before Cout)
    4. currentl limit without Cout

    As you can see in picture 1 the current has a freq. of 385kHz. In Pic 3 you can see the max. Peak of 1 A before the TPS limits the current. The input voltage of vin of 24V are generated by a flyback converter with 385kHz switching frequency.  When Cout is getting removed, the curicuit works as expected Pic 4.

    The customer thinks a a filter at the input could help. He will implement that. 



  • Hi Jan,

    Thanks for the measurements. The current limit loop in the eFuse devices is slow, so, the eFuse takes time to respond to the switching currents. Your approach is current. Stabilizing the input voltage helps

    Best Regards, Rakesh