• State
  • Locked Locked
  • Replies 8 replies
  • Subscribers 64 subscribers
  • Views 1725 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS2115ADRB - Current limit register

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: TPS2115A, TPS22981, TPS2560A, TPS22953

Hello,

Could you please let me know the recommended ILIM resister for 2A(min) current limit setting?

In the datasheet, there are the specification for 1.25A(typ) and 0.71A(typ) only.

Current limit equation is 500/R.
For 1.25A current limit, the current limit accuracy is about  -24%, +24.8%.
Thus I think that I can use the following equation for estimate resister  of 2A(min) current limit.

Ilim(min) = 380/R
Ilim(typ) = 500/R
Ilim(max) = 624/R

Thus, we should use 190ohm for 2A(min) current limit.
Is my understanding correct ?
Also if we use 190ohm, the Ilim(max) will be 3.28A.
Is this acceptable?

Best Regards,
Ryuji Asaka

  • 0
    TI__Expert 4065 points

    Hi Ryuji,

    According to your calculated RILIM = 190ohms, your 2A (min) current falls within max recommended operation for the TPS2115ADRB, please see screen shot from datasheet below.

    Also your calculated 3.28A (Max) current will fall above the absolute max ratings for this device, please see screen shot from datasheet below.

    So it is not recommended to use 190ohms RILIM.  

    Best,

    Haidar

  • 0 in reply to Haidar Hamoo
    Guru 20090 points
    Hello Haidar,

    Thank you for the reply.
    If we use external 2.5A current limit device, can we use 190ohm as current limit register for 2A(min) current limit?

    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Expert 4065 points
    Hi Ryuji,
    So your TPS2115ADRB device will be operating with a current level above 2A (min) which is the limit for max recommended operation current for this device and that's why it is not recommended since your are stepping in the gray area between max recommended operation condition and the absolute max ratings for this device, but I can suggest another device that might be more suitable for your application, please check the TPS22981 power mux. The TPS22981 has more features than the TPS2115A, please let me know if you have further questions.

    Best,
    Haidar
    Please consider checking the "Verify Answer" button if I've answered your question.
  • 0 in reply to Haidar Hamoo
    Guru 20090 points
    Hello Haidar,

    Thank you for the reply.
    I checked that the TPS22981 datasheet.
    This device current limit is 1.8A(min).
    Our customer requirement is 2A(min) current limit power mux.

    Are there other device?
    For example, the TPS2560A can support 2.1A(min) current limit dual power switch.
    If we short the OUT1 pin to the OUT2 pin, can I use this device as power mux?

    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Mastermind 42795 points
    Hi Ryuji,

    I will move this post over to the load switch forum so that their experts can provide more suggestions.

    Load switch team, do you have a suggestion for a power mux for currents > 2.5A?
  • 0 in reply to Eric Wright
    TI__Genius 15780 points

    Hi Ryuji,

    Does the power muxing solution need to have a current limit, or is the only requirement reverse current blocking? Also, is a voltage dip on the output acceptable when transitioning from one supply to another?

    Thanks,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    Guru 20090 points
    Hi Alek,

    Please see the following as reply.

    Current limit is not necessary. If there is current limit, we can set the current limit above 2A(min).
    Reverse current blocking is necessary.
    The voltage dip on the output is acceptable when transitioning from one supply to another.
    Also, the voltage rails are 5V(typ.)
    2 in 1 power selector

    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Genius 15780 points

    Hi Ryuji,

    Thank you for the information.

    In general, power muxing can be accomplished using two load switches with reverse current blocking. Since you need >2A, I would either recommend two TPS22963C devices or two TPS22953 devices. The configuration for these load switches can be found in the drawing below.

    Also, you can find more information about the power muxing for the TPS22953 in the datasheet (section 10.1.6). Let me know if you have any questions.

    Thanks,

    Alek Kaknevicius