BQ24160: Reverse boost protection

Figure 1,                                                                                                                                                               Figure 2.

Hi Jingle,

At what battery voltage does this happen?

Regards,
Jeff

Hi Jeff,
Without using the Battery, and we use the QFN package to implement,
maybe something wrong for this application schematic,
So, could you please add a diode to EVK to check this issue?

thanks,
Jingle

Hi Jeff,

            From our test, if no battery and no diode, the input voltage (Charger IN) was stable and no voltage ringing, 

            But if no battery and add diode, the input voltage (Charger IN) have voltage ringing,

           Could you explain why use diode is going to have voltage ringing on the input?

thanks,

Jingle

Hi Jeff,

           Thanks for your quick reply, we do some testing about that application schematic (No Battery and have diode), as below,

           1. Using AC to USB adapter to supply to our device (Only USB Power, No USB signal), the charger output voltage is stable and our device is working properly

           2. Using DC Power Supply (Model: Tektronix PS280) to supply to device, we found that the charger output voltage isn't stable, we check some pin behavior of the charger, please see the next,

                  A, Test Point figure, TP1 for IN pin, TP2 for Boot pin, TP3 for SW pin,

               

         B, TP1/TP2/TP3 figure

             

      C, We add 220uF to the IN pin, the TP1 voltage seems to be smooth(PMIDI is similar to TP1), but the charger output voltage isn't stable, we found the TP2 (SW2) switch in different frequency

            (Working device frequency or PWM/Duty is 708ns stable, not 60ns, and NO switching )

           

       Base on the above test, the charger seems to do re-boot constantly when the frequency switching, just only add diode into the IN pin,

       The TP1 diode are directional, why to use the diode and DC power supply have to produce incorrect PWM output in the SW PIN?

       I guess it should be dependent and is it possible to have a relationship between the frequency and the internal setting procedure of the charger?

Jingle

Jingle,

The last plots looks as if the charger is running in max duty cycle mode. Is that plot with both 220uF at TP1 and the diode?  What is the voltage at the IN pin? 

Regards,

Jeff

Hi Jeff,

             We add 200uF between diode cathode and IN pin,

             The input voltage is 5V!

thanks,

Jingle

Hi Jeff,
1. With reverse boost protection disabled and the diode, there is a risk of boost back.
=> this phenomenon we will keep an eye on when we use it.

2. We modify our MCU FW and use DC power input, first, the charger has Vsys output stably, MCU will write SDA data (Vdpm=4.6v) to Charger by I2C bus, base on application schematic that we use a diode to do reverse protection, a diode has 0.3~0.4v voltage drop (if use DC=5V), charger IN pin voltage seems to less than Vdpm register setting, the charger will turn off Vsys output, so our MCU is all disable because of no MCU power input, now I think it's a right process,

About the above description, could you provide the detailed internal voltage comparison structure of charger for our reference,

thanks,
Jingle

Jingle,

Can you be more specific about the internal voltage comparison structure to which you are referring?

Regards,
Jeff

Hi Jeff,

           For example, charger IN pin voltage=4.5, and the charger Vin_dpm setting 4.6V,

           BQ24160 internal how to judge or compare voltage between Vin and Vin_dpm, and decide the SW pin has no output?

           We want to know this procedure of the charger, please tell us.

thanks,

Jingle

Hi Jeff,

           It's clear to me now,

           By the way, what is the allowable range of voltage that VIN is close to Vin_dpm? 

           For BQ24160 datasheet, VIN_DPM threshold accuracy: -2%~+2%

           So, VIN_DPM=4.6V, the range is equal to 4.692V, If VIN < 4.692V, the SW output will be closed.

           Is it correct?

thanks,

Jingle