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TPS25947: ILIM Set Resistor Question

Wesley Mandel
Prodigy 50 points
Part Number: TPS25947
Other Parts Discussed in Thread: TPS25946,

Tool/software:


Hello,

I see in the datasheet for the TPS25474 family that it is generally rated for 0.5A to 6V for its current limiting capabilities. Are these the firm limits of the device's capabilities? 

I have this device in several locations for a PCBA where I generally follow this, but in a couple of locations I would like to limit the current below 500mA to something closer to 325mA. Is the device capable of limiting current at this level? 

Attached is a schematic example of where I have not observed the device's ILIM set point rating:

 

I can likely correct this to be within the rated limits, but was curious if this is still a viable implementation. Are there any behaviors that TI recommends I look out for or any improvements to the implementation that TI suggests? 

Also, I understand that it is a different device, but does any feedback given here also apply to the similar TPS25946 series as well? 

Thank You,

Wesley Mandel

  • +1
    TI__Mastermind 38965 points

    HI Wesley,

    Wesley Mandel said:
    Are these the firm limits of the device's capabilities? 

    Higher than rated current can cause damage to FET. Lower currents i.e. below 0.5A won't cause any damage to FET. It is more of a current limiting accuracy of device limitation.

    Wesley Mandel said:
    I have this device in several locations for a PCBA where I generally follow this, but in a couple of locations I would like to limit the current below 500mA to something closer to 325mA. Is the device capable of limiting current at this level? 

    The device wasn't made for that so will have worse accuracy (around 15-20% current limit accuracy). Also we don't test this in production nor do we have full validation data for <0.5A current limit. This 15%-20% number is from design team + small sample set validation across temp. TI won't guarantee this in the datasheet so I would recommend you to validate this at your end also. 

    Wesley Mandel said:
    Are there any behaviors that TI recommends I look out for or any improvements to the implementation that TI suggests? 

    Nothing else other than above mentioned.

    Wesley Mandel said:
    Also, I understand that it is a different device, but does any feedback given here also apply to the similar TPS25946 series as well? 

    Same story as TPS25947 as they are from same family so lot of common ip blocks.

    Best Regards,
    Arush

  • 0 in reply to Arush Gupta
    Prodigy 50 points

    Thank you for the clarification here. I will verify on my side about the current limiting range, but it is nice to know it is possible just with a wider tolerance. I appreciate the help here!