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BQ78350通讯隔离问题

user4236824
Intellectual 390 points
Other Parts Discussed in Thread: BQ78350

第一个问题：BQ78350通讯输出如果采用隔离芯片会有3-5mA的自耗电，隔离IC的供电我用放电FET控制脚来控制，当过放保护就切断隔离IC的供电。这样就不会把电芯损坏。但客户不同意在正常情况下有3-5mA电流。所以想将隔离IC改为两个高压的NMOS管。在通讯端口增加5V的TVS管。这样的话自耗电就减小了。但不知道有没有什么风险。第二个问题：BQ78350是库仑计的为啥规格 书里面还会提到默认写入化学ID是1210。难道这IC是阻抗跟踪的？

  • 0
    TI__Guru*** 130456 points
    您好，关于SMBUS隔离请参考下面的答复：
    e2e.ti.com/.../601218
    BQ78350是CEDV算法
    The bq78350 uses the chemistry of the cells to estimate the state of charge of the pack after a reset.
    Chemistry information is not loaded to the device as a Data Memory parameter but by using the Chemistry
    view. Loading the chemistry is not required for simple operation of the EVM but will be desired for setup of
    the board or a part for operation with cells, particularly if the chemistry differs from the default
  • 0 回复 Star Xu
    Intellectual 390 points

    文章里面的是带EV2300那可以不用。毕竟EV2300可以不用考虑自耗电，但我是接在电池里面。

  • 0 回复 user4236824
    Expert 2180 points
    后面是怎么解决的 分享下 谢谢
  • 0 回复 user4236824
    TI__Guru*** 130456 points
    您好，请参考下面的答复：
    I assume the pullup voltage for the bus is off to the right, is this correct? Then they need to be careful they get sufficient voltage passed through to the device (which I assume is on the left side of the diagram). For example, if the bus pullup voltage is 3.3V, then if DOUT is also driven with a 3.3V level, there will be a Vgs=Vth voltage drop from the voltage on the right side to what gets to the left side. The 2N7002 transistor has a Vth max = 2.5V per the Nexperia datasheet, which means only ~0.8V may get to the device. Realistically subthreshold operation will allow a higher voltage when current is very low, which is expected when the device is not pulling down the pin. If they can drive DOUT with a higher voltage, such as 5V or higher, then it will be more robust.