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BQ25892: Design Help/Clarification

Renan Santos Adriano
Mastermind 22380 points
Part Number: BQ25892

Hi team.

My customer is currently working with BQ25892 wanted to know some clarification.

1. If the VBUS input is zero or not connected, and the battery is already full, does the battery back power the IC?

2. Can it detect a reverse battery polarity? How?

3. There is a pin, /CE or Charge Enable pin. If I toggle this pin to LOW, it charges the battery. If I toggle this pin to high, does it disengage the BAT and SYS pin and put these pins to high impedance?

4. In the specs, on page 6, it shows this, regarding the /CE pin, "Battery charging is enabled when CHG_CONFIG = 1 and CE pin = Low." What happens if I put the CHG_CONFIG = 0 and CE pin = Low? Does it have the same effect as CHG_CONFIG = 1 and CE pin = HIGH?

Thanks in advance.

Renan

  • 0
    TI__Guru**** 167236 points

    Hi Renan,

    1. No.  Q1 FET from VBUS to PMID provides reverse leakage protection so that the battery voltage does appear on VBUS.

    2. No. If a battery is inserted in reverse, the IC will be damaged.

    3. No. /CE pin only prevents current from flowing from SYS to BAT to charge the battery.  If the battery needs to supplement SYS current, current can still flow from BAT to SYS.

    4. If CHG_CONFIG bit = 0 OR /CE = high, charge is disabled.  Both CHG_CONFIG bit = 1 and /CE pin = low are required for charging.

    Regards,

    Jeff