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BQ25723: Circuit review and help some issues

Part Number: BQ25723

Hi Sir/ Madam 

Please help to review the circuit.

I have few questions.

Please help to solve the issues

1. There is an 'A' letter inside my circuit. If the resistor is 121K, the inductor is 2.2uH and this pin isn't connected to any device, it can work properly?

2. See the letter 'B' inside my circuit. When the battery is full charged, the mosfet isn't turn off. Do you know why? 

    I measured Vg and Vd and Vs, and I got Vd = Vs and Vg is low.

3. We turn on the system, the NVDC starts to work.

    The input voltage, ADPIN_T, is 12.44V.

    The VSYS voltage, DCINP, is 6V~8.4V.

    The battery voltage, UPSBAT, is 6V~7V because isn't full charged yet.

    The bug is that charger stop bucking the input power to output, and battery starts discharging.

    We can see the SYSOVP flag becomes high, but we cann't find VSYS is over 12V.

    Why SYSOVP flag becomes high?  

    The temperature is 27  .

  • 您好,收到了您的案例,调查需要些时间,感您的耐心等待。

  • Hi 
    我忘了是PO在中文論壇,我用中文描述一遍

    "

    請幫忙Review電路

    另外還有幾個問題請幫忙解答

    1. 附檔電路上標示"A"的地方,電阻使用的阻值是121K OHM,電感為2.2uH,IADPT沒有接到其他晶片上,這樣搭配電路上運作會有問題嗎?

    2. 附檔電路標示"B"的地方,當電池已經滿充,但MOSFET卻沒有關閉,這是什麼原因呢? 

        我有量過MOS的三隻腳的狀態來判斷MOS是否是開的,Vd=Vs且Vg為Low,代表PMOS為On狀態
    3. 當我們對系統上電,此時NVDC會開始運作

        系統的輸入電壓是ADPIN_T其電壓準位12.44V

        經過NVDC降壓後的電壓為VSYS,在我的電路上取名為DCINP,其電壓為6V~8.4V (看當時電池電量多少而定)

        電池是2S1P且測試時的電量為低電量,約6~7V左右。

        發現的問題是,NVDC關閉了converter作用而電池開始放電

        我們檢查register,看到SYSOVP變成1但我們從波型上卻沒有抓到Over Voltage的12V

        想請問還有什麼原因會造成SYSOVP變成1呢?

    PS: 我們量到的溫度27度左右

  • 1. The converter still operates despite the mismatch inductance detection, it will probably hurt light load efficiency, since inductance is used in the light load operation. 

    2.  BQ25723 could not terminate the charging even if the VCHG is met. Need external command to set charge current to zero. 

    3. If SYSOVP is high, you need to monitor the VSYS rail to see if any transient or spikes.