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BQ27Z746：HW Threshold OCD不能超过-20mV

rong hero
Prodigy 140 points
Other Parts Discussed in Thread: BQ27Z746, BQSTUDIO

零件编号：BQ27Z746

工具/软件：

我有一个问题困扰我很久了，我知道在数据内存=>Protections=>HW threshold targets可以设置OCD的阀值，比如设置成-28mV，我选用的Rsns电阻是20mohm，当电阻两端电压接近-20mV（约0.9A）时，就会触发OCD保护，关断输出。这与规格书的可设置范围（-4~-100mV）不符。（为了防止软件OCD提前保护了，我将电流特意设置成-2400mA），我做了验证，Rsns无论多大电阻，它两端电压的都是接近20mV时，就会触发保护，能告诉我这是怎么回事吗，需要如何处理才能使Rsns上电压大于-20mV不会被关断，谢谢

  • +1
    TI__Mastermind 24931 points

    Hello, 

    Changing the HW protection trip value in data memory has no effect on the trip threshold. Instead this serves more as a reference to what value you have calibrated the HW protections for. 

    In other words, changing the HW trip thresholds in data memory does NOT change the trip thresholds, the only way to change the HW based protection trip thresholds is to use the calibration tab in bqStudio, or to manually write to ProtectorImage2. 

    I recommend you read this application note in detail as this goes over the entire HW based protection calibration procedure. 

    Regards, 

    Robert.