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TPS7B7702-Q1: 1mA current sense value

Kuramochi Tadahiko
Guru 28715 points
Part Number: TPS7B7702-Q1

Hi,

My customer would like to sense following current.

- min:1mA, typ:2.5mA, max:4.0mA

Is this practical?

They are worried false detection that 1mA(min) detect as open by dispersion of each component characteristics.

Best Regards,

Kuramochi

  • 0
    TI__Guru 55940 points

    Hi Kuramochi,

    It is important to note that the output current to sense pin current ratio accuracy is not ensured for output currents less than 5 mA.  Furthermore, as shown in the Electrical Characteristics table, the accuracy of this ratio decreases as the output current decreases.

    The voltage on the sense pin will still follow Ohm's Law at the lower output currents.  It is the ratio Io / 198 that will not be as accurate as it is with higher output currents.

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    Guru 28715 points

    Ryan-san,

    Thank you for your answer.

    My customer would like to no sense but only detect "open load".

    In this case, can TPS7B770x detect 1mA(min)?

    Best Regards,

    Kuramochi

  • 0 in reply to Kuramochi Tadahiko
    TI__Guru 55940 points
    Hi Kuramochi-san,

    TPS7B770x outputs the current onto the sense pin as a ratio of the output current. This current flows through the external resistor on the sense pin creating a voltage. As shown in Table 1, an open load voltage follows this pattern the same way it does during normal operation. The determination as to what voltage on the sense pin is considered open load, normal or over-current is done external to the LDO.

    It is important for the customer to understand that at 1mA load current, the accuracy of the ratio between the load current and sense pin current is not specified. The lowest load current that has a specified ratio accuracy is 5mA.

    Very Respectfully,
    Ryan