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TPS2120: Setting current limit beyond Rlm reccomended values

Leo Chow
Expert 3120 points
Part Number: TPS2120
Other Parts Discussed in Thread: TPS2121, TPS2115A

Hi,

i'm working on circuitry validation with my client & we're looking into potential methods to reduce current limit of TPS2120 to 650mA, but according to Ilm formula the Rlm recommended value not to exceed 100kOhm. Hence i would like to know if there's any other variables i should look into to meet my target current limit? Also what may the potential implications i face if i go beyond 100kOhm for Rlm? Thanks.

Regards,
Leo

  • 0
    TI__Genius 10855 points
    Hey Leo,

    Thanks for reaching out on E2E!

    The TPS2120 has about 500mA range from the typical value. For example, if you configure a 85kohm resistor on the TPS2120, the current limit could vary from 1 - 2A. At RLM values higher than 100kohm, the accuracy of the current limit could drop, and the 500mA range still has to be accounted for.

    Therefore, with a higher RLM value, the current limit will not be as accurate and in this case, could potentially prevent current from passing downstream (since the current limit could be 650mA - 500mA).

    Can you provide more details on why the 650mA current limit is required? Would a 1 - 2A limit work instead?

    Thanks,
    Arthur Huang
  • 0 in reply to Alpha H
    TI__Expert 3120 points
    Hi Arthur,
    Customer is trying to limit at 650mA as it's used for charging a battery at 450mA. if that's the case should they be changing to another device with lower current limit? Please advise. Thanks.

    Regards,
    Leo
  • 0 in reply to Leo Chow
    TI__Genius 10855 points

    Hey Leo,

    What's the voltage range of the application? They could use the TPS2115A if this is a 5V application. Otherwise, would a battery charger at the output of the TPS2121 work? This should limit the current as well, to my understanding.

    Thanks,

    Arthur Huang

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