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Original question:

BQ24618: Phase-1 Precharge Anolmaly

BQ24618: BQ24618: Phase-1 Precharge Anolmaly

Thomas Bouchard
Prodigy 230 points
Part Number: BQ24618

Hi,

This problem was related to noise on the SRN and SRP battery current sense resister traces back to the 24618 chip.  Although I paired the traces, they were routed too close to the high-current switching lines.  In addition, the SRP/SRN decoupling caps were near the current sense resister instead of the IC pins.

I soldered a chip decoupling cap to the SRP/SRN lines near the IC, and the charger worked better...but still not perfect.

I created another PCB, ensuring those lines were not near the high-current signals, and placed the decoupling caps near the IC pins.

The resulting design then worked perfectly.

Tom

  • 0
    TI__Genius 10240 points
    Hi Tom,

    We fully agree that the layout with control signal traces staying away from the high-current signal traces, especially the trace with high di/dt and placing the decoupling caps near the IC pins are crucial for normal operation. There is a layout guideline at the end of the datasheet for the best practice. Thank you for sharing your experience with us.