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BQ76952: Temperature performance of VREF2 used in ADCs for current measurement

mison yao
Prodigy 40 points
Part Number: BQ76952

Hello, when measuring current, the reference voltage used by the ADC is VREF2, but I feel that the temperature performance of VREF2 is worse than that of VREF1, does it affect the accuracy of the measurement, and does it automatically calibrate the temperature in real time inside the chip?

  • 0
    TI__Expert 4915 points

    您好

    https://www.ti.com/lit/ug/sluuby2b/sluuby2b.pdf?ts=1721192350714

    根据官方的TRM显示是有相关的方式来校准和反馈是否出现精度问题

    The BQ76952 device integrates a diagnostic check on the voltage references used by the device. VREF2 is used by the coulomb counter and LDOs, including the REG18 LDO. The REG18 LDO voltage is periodically measured using the voltage ADC (using VREF1 as its reference) and can be read back in bytes 0–1 of the 0x0075 DASTATUS5() subcommand. This command should normally report a value of approximately 29137. If it differs significantly from this, it may indicate that one reference has changed in value significantly relative to the other, meaning reported measurements may no longer be accurate. This ratio is monitored periodically and, if the value is below 26223 or above 32051 for four seconds, the device can trigger a VREF PF (VREF) and disable the battery pack. This PF can be enabled by setting the Settings:Permanent Failure:Enabled PF C[VREF] and Settings:Manufacturing:Mfg Status Init[PF_EN] configuration bits.

    11.2 VREF2 Versus VREF1 Check The VREF2, which is used by the coulomb counter and LDOs, is measured indirectly using the voltage ADC (which uses VREF1) to measure the REG18 voltage (which is based on VREF2) and can be read back in bytes 0–1 of the 0x0075 DASTATUS5() subcommand. This command should normally report a value of approximately 29137. If it differs significantly from this, it may indicate that one reference has changed in value significantly relative to the other, meaning reported measurements may no longer be accurate. This ratio is monitored periodically and, if the value is below 26223 or above 32051 for four seconds, the device can trigger a permanent fail (PF) and disable the battery pack. This PF can be enabled by setting the Settings:Permanent Failure:Enabled PF C[VREF] configuration bit.

    这是部分说明具体部分请参考给您分享的以上链接。