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BQ24725A: ACDRV pin has no normal output

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Replies: 6

Views: 156

Part Number: BQ24725A

1. Chip pin status:  VCC pin is 15V, ACDET pin is 2.7V, RENG pin is 6V, ACOK output is high, I2C bus can work normally, 3 lithium battery is installed or not installed.

Problem:The ACDRV pin does not have a normal output and the voltage is approximately 0.4V.

The three conditions of the ACDRV normal output in the manual are satisfied. The VCC voltage is 15V higher than UVLO. The ACDET is 2.7V, greater than 2.4V, less than 3.15V, and the battery voltage is 0V or 12V, which is 275mV less than VCC.


2. What is the function of C17 on  the manual(pag 28)?If I remove C17, the chip can work normally?

  • Hi,

    1) Can you please make a table with the following voltage measurements? VBUS, VSYS, VBAT, VCC, REGN, ACDRV, CMSRC, ACOK, and ACDET. Please take these measurements once with no battery connected and again with the battery connected.

    2) C17 slows down the turn-on of the ACFET, as shown below. The device should still be able to work without C17, but the faster turn-on could cause more inrush current.

    Best regards,

    Angelo

  • In reply to Angelo Zhang87:

    Hi:

    1. The chip has no VSYS pins, so there is no test. Other test data are as follows:

    2. The following picture shows the ACDRV waveform after power-on. ACFET will be latched off and failure is detected seven times.

    Best regards,

    Rengui Sun

  • In reply to rengui sun:

    Hi Rengui,

    What is your adapter's voltage and current capability, and do you have a system load connected? I don't understand why your VCC is higher than both VBUS and VBAT. VCC should be a diode OR between the two. Please send me your schematic.

    Best regards,

    Angelo

  • In reply to Angelo Zhang87:

    Hi Angelo,

    Thank you for your reply.

    1. The adapter is an isolated DCDC power supply with an output voltage of 15V and a maximum current of 10A.

    2. Currently debugging, the load is 0A, and the U10 in the figure below has been removed.

    3. In the figure, the 1 pin of D7 has been floated, and the G and D poles of D2 are also connected in parallel with a 2.2nF capacitor.

    4. I said that VBUS is the power supply for the I2C bus. I didn't understand what you meant yesterday.

    Best regards,

    Rengui Sun

  • In reply to Angelo Zhang87:

    Hi Angelo,

    Thank you for your reply.

    Our problem has been solved. Because the layout design is wrong, the chip is working abnormally. Sorry,Sorry.

    Best regards,

    Rengui Sun

  • In reply to rengui sun:

    Hi Rengui,

    Thank you for the update! I'm glad the issue was resolved.

    Best regards,

    Angelo

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