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INA300-Q1: Is low current detection feasible?

Ben Huang1
Intellectual 575 points
Part Number: INA300-Q1

Hi Sir

 

INA300-Q1 is for Over Current Protection.

 

We would like to implement the similar function but low current detection

 

Load current of 5mA flow through RSENSE = 10mohm

The differential voltage = 50uV

 

 

Does INA300-Q1 is suitable for this application or any parts else to recommend?

 

 

Thanks

Regards

Ben

  • 0
    TI__Genius 17990 points
    Hello Ben,

    The INA300-Q1 cannot measure a differential voltage of 50uV, the offset alone is 500uV. I have a few questions for you so that we can help you find a suitable device:

    What common mode voltage will you be using?

    Is your common mode is going to exceed the supply?

    Do you need a Q1 device?

    Do you have any bandwidth requirements?

    If you have a schematic that you are able to share, that would also help us find you the correct device.
  • 0
    Intellectual 575 points
    Hello Mitch

    Please find our reply as follows


    (1) Common mode voltage < 1V
    (2) Common mode is not going to exceed the supply
    (3) Q1 Device? Rsense? Not required , the pass element will be externally installed
    (4) Bandwidth < 10kHz
    (5) Control Pin Requirement: The simpler, the better

    VCC, GND, IN+, IN-, ALERT

    (6) Input bias current : the lower, the better (no input bias current is the best)



    Application: Power Bank
    Function: Cable plug detection

    Brief description

    N type MOSFET acts as RSENSE
    (Fully turn on to get about 10mohm resistance), its drain connect to the GND of USB port and the source connect to the system GND

    The target differential voltage between different GND is 50uV, if low charging current flow through the RSENSE, current sense comparator must send a signal (Alert) to inform system "end of charge" and then turn off the MOSFET to save power consumption


    Thanks for helping
    Regards
    Ben
  • 0 in reply to Ben Huang1
    Intellectual 575 points
    Sir

    Thanks for your suggestion; we may find the suitable part for our application.
    We will also consider the power dissipation if maximum current flow through the pass element.

    We have no any experience to measure the voltage of “uV” class, Inherent noise is the biggest concern.
    TI has any documents or tips to guide us?

    Regards
    Ben
  • 0
    TI__Expert 5830 points
    Hello Ben,

    I am happy to help you with "under current protection" circuit using precision op amps. I have a couple of questions below that will help in finding the right solution.

    Is the sense resistance on the high-side or low-side of the load?
    What is the potential of the source?


    Best regards,

    Errol Leon
    Texas Instruments
    Precision Op Amps Applications
  • 0 in reply to Errol Leon6
    Intellectual 575 points
    Sir


    The sense resistance is on low-side of the load.
    The under current detection is intended to USB charging, the potential of the source should be about 5V.


    Regards
    Ben