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BQ24074: BQ24074 CHG pin not pull low

Star Xu
Genius 9645 points
Part Number: BQ24074
Other Parts Discussed in Thread: BQ28Z610, , BQ28Z610-R1

Hi

The customer design with BQ28Z610 and BQ24074, The circuit of BQ24074 will maintain hi-Z when CHG (BQ24074 pin9) does not pull low for the first charging after the shipping mode is set in system.

Attached the schematic for your reference.

TP01S041A1電路圖 2022.09.15 (1).pdf

It looks like the chip in shipping mode Wake up from charging, but determined battery absent mode.

MCU has no control light, and LED is directly connected to CHG.

Please give some suggestions.

Thanks

Star

  • 0
    TI__Mastermind 23410 points

    Hi Star,

    Star Xu said:
    It looks like the chip in shipping mode Wake up from charging, but determined battery absent mode.

    Can you clarify how the system is being put into ship mode? Neither the BQ24074 nor the BQ28Z610 have a shipmode feature implemented within the IC.

    For the BQ24074 portion of the schematic, are the /PGOOD and /CHG pins pulled up to a voltage? I only see a resistor pulled up to some signals DC_OK and CHRG_OK. As these pins are open drain outputs, they do require a voltage pull up. 

    I'll look for feedback regarding the BQ28Z610 portion of the schematic. 

    Star Xu said:
    It looks like the chip in shipping mode Wake up from charging, but determined battery absent mode.

    How is this being determined?

    On the charger size, are you able to provide a voltage waveform on the ISET pin, VBAT pin, and /CHG pin? 

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    TI__Genius 9645 points

    Hi Anthony

    Thanks for your help.

    1. We use command “AltManufacturer Access() 0x0010 SHUTDOWN Mode” to set BQ28Z610-R1 to shutdown mode, before shipping.

    2. Yes, /PGOOD and /CHG are pulled up to 3.3V via a resistor and an indication LED.  We observed that /CHG does not pull low (no LED light) on some of the PCBAs.  Not every PCBA has such behavior when wake up from shutdown mode. 

    Now the 1.5k ohm on the charging board circuit diagram should be 0 ohm (you can also directly remove the resistor), there is a resistor and LED on our side of the MCU board to 3.3V.

    Thanks

    Star

  • 0 in reply to Star Xu
    TI__Mastermind 23410 points

    Hi Star,

    Star Xu said:
    We observed that /CHG does not pull low (no LED light) on some of the PCBAs.  Not every PCBA has such behavior when wake up from shutdown mode. 

    Are you able to get a waveform of the BAT pin? Typically when the device does not see a battery, it runs the battery detection routine:

    This will help determine what the charger is seeing.

    Has a device ABA swap been done yet?

    Best Regards,

    Anthony Pham

  • 0 in reply to Star Xu
    TI__Mastermind 23410 points

    Hi Star,

    Are there any updates here?

    Best Regards,

    Anthony Pham