• Resolved

BQ25713: HIDRV pin not zero when no DC input is attached

Prodigy 130 points

Replies: 17

Views: 305

Part Number: BQ25713

Hi forum, 

Thank you in advance for your time. 

My design with BQ25713 encounters an issue. When there is only battery attached to the system and no register is set, I measured a voltage at HIDRV1 and HIDRV2 with behavior as shown in Figure 1.    

With no DC input connected, the same voltage is transferred to Vbus which caused the charge status reg to show Adapter Present. 

If I uncheck the EN_LWPWR, disabling the low power mode, HIDRV1 and HIDRV2's behavior change to as shown in Figure 2 and Figure 3. 

  Figure 1 HIDRV1 and HIDRV2 with only battery attached

        Figure 2 and 3, HIDRV1 and HIDRV2 reset period change from 3.58s to 5.24s for different PCBs. 

If I enable HIZ mode, the voltage on HIDRV and Vbus stays around 3.5V. 

Comparing to EVM, HIDRV and VBUS should be zero when there is no DC input. 

I also attached the screen capture of my schematic and layout. 

Please feel free to ask if you spot any error or need more information. 

Thank you

Jerry 

  • Hi Jerry:
       

        Would you please provide detail information below for further analysis:
      

        1,What is the VSYS and VBAT voltage respectively for these test?

        2, How much load do you add on the system?

        3, Do you measure out the Vbus voltage when DC input is disconnected?

    Regards

    Shishuo

  • In reply to Shishuo Zhao:

    Hello Shishuo,

    1,What is the VSYS and VBAT voltage respectively for these test?

    ans : In Figure 6, yellow being HIDRV1 and blue being Vbus voltage. Here, low-power mode is enable from power on.  VBAT voltage is stable at the 10.3V. 

     

       

     Figure 6

     Figure 7 VBAT is stable at 10.3V

    2, How much load do you add on the system?

    ans: I tried loading from a few mA to 2A. the shape of the signal that not change. 

        3, Do you measure out the Vbus voltage when DC input is disconnected?

    Ans: I don't measure out the VBus voltage, but I read the reg AC STAT with a mcu as a feedback if the DC is connected. It seems when Vbus >3.2V, AC STAT consider there is a input source.

    Please let me know if you need more info

    Best regard 

    Jerry 

  • In reply to jerry liang:

    Hi Jerry:
      

         The Vbus voltage looks weird with so obvious ripple. You can check your measurement setup to make sure it is grounded properly. 

         For Figure 7, what is the CH2 signal? it looks much different with Fig6.

         What is the work mode of this test? I need to exactly steps how do you come to this waveform from your hardware startup. These will be helpful.

         Note please include switch node information for all the future waveform measurement. HIDRV1 should come with SW1 and HIDRV2 should come with SW2.

    Regards

    Shishuo

  • In reply to Shishuo Zhao:

    Hi Shishuo, 

    SW1 looks the same as HIDRV1 in this case, and I connected VBUS and SW1 with a 1 ohm resistor in the schematic. This follows the EVM as JP7 is connected with P1 and P2. So as SW1 toggling, Vbus follows. I confirm that the grounding of my measurement is correct. 

    For figure 7, CH2 is VBAT. It stays at 10.3V with no affect on HIDRV2. 

    The device should be in boost and buck mode as power on. I have not set any register yet. I connected the battery and start reading the registers with EV2400. 

    This behavior, HIDRV2 and SW2 not zero,  is not observed from EVM. 

    I wonder if there is any mistake I made in the schematic creates this issue. 

    Best regard 

    Jerry  

  • In reply to jerry liang:

    Hi Jerry:
       

         Below is our TI EVM  schematic:

         JP7 P1 connected to VIN through 1ohm resistor.

         JP7 P2 connected to IC Vbus Pin,

         JP7 P3 connected to buck boost input terminal.

         Please remove 1 ohm resistor between VBUS and SW1 and have a try again. Let me know if it works normally.

    Regards

    Shishuo

  • In reply to Shishuo Zhao:

    Hi Shishuo, 

    Please note on my schematic that the 1 ohm resistor is connecting between DC input and VBUS, not between VBUS and SW1. There will be be power to the charger once I remove it. 

    To follow the EVM schematic strictly, I tried to remove the 1 ohm resistor, then directly connect VBUS to buck boost input terminal (drain of Q1 ). 

    But It dose not seem to do anything to the situation. 

    Best regard

    Jerry 

  • In reply to jerry liang:

    Hi Jerry:
       

         Sorry for the misunderstanding. It should be fine if 1ohm is between Vbus and Vin.

         Would you please include the SW information in the waveform for further analysis? 

    Regards

    Shishuo

  • In reply to Shishuo Zhao:

    Hi shishuo,

    Sure, let me update the figure as soon as I get back to office on Monday.

    Thank you

    Jerry

  • In reply to jerry liang:

    Hi Jerry:
        

         Thanks Jerry, please probe VIN, SW1, HIDRV1,BTST1 waveform under both no system load and 2A system load for analysis purpose. 

    Regards

    Shishuo

  • In reply to Shishuo Zhao:

    Hi Shishuo, 

    The updated waveforms have been attached.

    Ch1 yellow is BTST1, CH2 blue is Vin, CH3 purple is SW1, CH4 green is HIDRV1.   

    there is no different behavior observed between zero load and 2A load. 

    And the frequency of the event, shown in the BTST zoom out, is the same for zero load and 2A load. 

    Best regard 

    HIDRV no zero Photos.zip

    Jerry