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BQ25886: Protection circuit for D+ and D- pin

Satoshi
Guru 19645 points
Part Number: BQ25886

About D+ and D- pin of bq25886, these pins are damaged by many times insert and pull out the magnet switch.

When damaged board, these are occur only 250mA current. (ILIM is 500mA or over)

Please let me know about two points USB protection below;

①Currently D+ and D- pin connecting 5.6V/200mW zener diode.

　Is zener diode effect to correct protection?　

②Is there application note or reference circuit for protect D+ and D- on bq25886? 

Best regards,

Satoshi

  • 0
    TI__Mastermind 40305 points

    Dear Satoshi,

    Can you confirm if your output is drawing enough power in order to induce a 500 mA input current? In other words, if your input current is 250 mA at 5 V, the input power is 1.25 W. I would expect about 1.125 W of output power (8 V battery with 140 mA charge current). If this is your load, then there is no need for the charger to pull more than 500 mA input current. The input current limit is a limit meant for peak load (on the BAT and SYS). It will not always be met especially as the charge current is tapered down.

    Thanks,

    Mike Emanuel

    Please click "This resolved my issue" button if this post answers your question.

  • 0 in reply to Michael Emanuel35
    Guru 19645 points

    Michael-san

    Thank you for reply,

    I update customer condition and information for your question, please see below;

    ・Input side is drawing enough current.

    ・Sorry, I mistaken; ILIM setting is 1500mA.

    ・Target charge current is 900mA, but a few board occur drop to 250mA.

    　When once dropped to 250mA, I tried various measure(changed external parts, machine, etc) but charge current was not increase. 

    ・Current limit have enough margin, customer is not look like reach the current limit.

    First of all, are D+ and D- connect zener diode no problem?

    Is there reference protection circuit for D+ and D-?

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Mastermind 40305 points

    Satoshi-san,

    Can you please send a schematic so I can better understand your circuit? In addition, can you send waveforms of VBUS, SW, VBAT, and the battery current? Do you have a system load that could be taking some charge current? I am having trouble understanding your problem and this information will help me to better diagnose the issue.

    Thanks,

    Mike Emanuel

    Please click "This resolved my issue" button if this post answers your question.