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BQ76PL455A-Q1: Open Wire Detection

Kartik Shanbhag18
Intellectual 600 points
Part Number: BQ76PL455A-Q1

Hello,

We are using BQ76PL455A-Q1 IC in the design of our BMS for 14 Cells. We want to have an additional functionality where the BMS system displays a fault when the cell monitoring wires are improperly connected (no continuity) to the cells. In the datasheet, we came across the Open wire detection function and squeeze resistors, which can help in achieving our functionality. However we could not clearly understand how Open Wire Detection (OWD) works. Could you kindly help us with this?

Thank you in advance.

  • 0
    TI__Genius 11480 points
    Hi Kartik,

    At a high level, the open wire test utilizes the filter capacitor to see if the cell wire connection is present or not. When the squeeze resistor for a particular cell is turned on, it will discharge the filter capacitor if the wire is not connected, and the ADC measurement will reflect the lower voltage. If the cell wire is connected, the capacitor will maintain it's charge and the cell will supply the load current. In this scenario, the ADC measurement will only reflect the offset due to additional I*R drop.

    There is a thread about implementation that may be useful here:

    e2e.ti.com/.../2178958