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BQ34Z100-G1: Will a 0.5mohm sense resistor work?

Peter Upczak
Intellectual 965 points
Part Number: BQ34Z100-G1

Hi team -- Is there anything about the following application that would preclude reliable operation (SOC,SOH accuracy, optimization, golden image production, etc) ?

Battery: LION K2 Energy LFP26650

Current boudaries: 90-100A discharge (max), 40-60A discharge (average use), 3A charge

Sense Resistor Value: 0.0005 ohms

We have been working on and testing a number of other applications using an OPAMP interface to mimic 0.0015 ohms to 0.0025 ohms to the BQ with some success, using the physical sense resistor value of 0.0005 ohms. We now have an application opportunity that can't afford to support any active components beyond the BQ core due to power budget in a long-term shelf-storage scenario.

thanks.

  • 0
    TI__Guru 73830 points
    The maximum voltage across the SRP / SRN pins is 125mV, so you could use a a 1 to 1.25 mohm sense resistor. Current measurement accuracy at low currents may be degraded, but the input offset for the coulomb counter ADC is 10uV, so the gauge may not be able to detect currents lower than 10mA. The gauge can only report currents up to 32A, so you wil have to use 4x current scaling to support the 100A.