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Original question:

BQ24610: Starting a high current battery charger design, is this the right part

BQ24610: Custom Board with power path but no DPM (not needed) - board seems to be stuck in sleep mode

Mike Sprauve
Intellectual 380 points
Part Number: BQ24610

Hello,

I have a custom board that uses the BQ24610 that does not utilized the DPM feature but does utilize the Power path feature. When I apply power to the board (Vin), the chip VREF is reading zero volts as if it was in sleep mode. I have attached the schematics as reference

 

  • 0
    TI__Genius 16532 points

    Hi Mike, 

    Thank you for reaching out!

    I will review your schematic and provide feedback by Friday.

    Best Regards, 

    Aya 

  • 0 in reply to Aya Khedr
    Intellectual 380 points

    Hello Aya,

    Thank you and I look forward to review and feedback

    Mike

  • 0 in reply to Mike Sprauve
    TI__Genius 16532 points

    Hi Mike, 

    Thank you for your patience. 

    I reviewed the schematic and here are some comments:

    1- Input protection is not present. We recommend two back-to-back P-channel MOSFETs to isolate the battery and adapter. This blocks reverse current from the battery back to the input. If MOSFETs are not used, then we we highly recommend a diode to block reverse current. 

    2- The VCC inrush current limiting resistor is typically 10 ohms. 

    3- Please refer to Table 4 from the datasheet: the output capacitance in your design should be 40uF. Currently, there is only 20uF present. 

    Please let me know if you have additional questions/concerns.

    Best Regards, 

    Aya 

  • 0 in reply to Aya Khedr
    Intellectual 380 points

    Hi Aya,

    Yes I understand all your suggestions but my main question is - Would any of these Items prevent the device from turning on. When I probe the board, Vref is sitting at 0V. I  have attached 2 set of scope images, the good_board.jpeg is a TI evaluation board and the bad_board>jpeg is my custom board. As you will notice in the images, it seems that on my board, it seem that the board enters into sleep mode (is that correct) or is there something else that could be causing this behavior

    Bad Board

    Demo Board

  • 0 in reply to Mike Sprauve
    TI__Genius 16532 points

    Hi Mike, 

    I will double-check with one of our experts to see what schematic changes are causing this. 

    In the meantime, If the SRN voltage is greater than VCC, indicating that the battery is the power source, the BQ2461x enables the BATFET and enters a low quiescent current (<15 uA) SLEEP mode to minimize current drain from the battery. You may want to double check the SRN voltage. 

    Best Regards, 

    Aya 

  • 0 in reply to Aya Khedr
    TI__Genius 16532 points

    Hi Mike, 

    Please follow the schematic checklist below to ensure that your design behaves as expected. 

    Also, refer to section 10.2.2 for the simplified system when the DPM feature is not utilized.

    3326.BQ24610_BQ24650_Schematic_Checklist.pdf

    Best Regards, 

    Aya