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BQ25125: Absolute maximum ratings of PMID current

Dmitry Dmitry78
Prodigy 120 points
Part Number: BQ25125
Other Parts Discussed in Thread: BQ25150

Hello. Could you help me with IC BQ25125. I have two questions.

1. BQ25125 has JEITA temperature system charging with quite large interval T warm - T hot. I use Li-ion battery with 45° C temperature limit and the battery manufacturer doesn't allow to exceed the limit. If I tune Thot as 45° C the T warm will bee on the level about 30 ° C with reduced charge voltage -140mV. It reduces efficiency of using battery capacity (30- 45° C ). My device has that temperature on the charging so I need make sustem with small interval T warm - T hot ( or without interval). Otherwise, the chip is completely suitable for me.
Is there a way to reduse T warm - T hot interval or to remuve it?

2 My device have a load that (conected directly to Pin PMID) consumes the pulse current up to 810mA 60 mS everey minut from battary. Average current is not above recommended I(PMID) Output Current 300mA and below Current Limit I(BAT OCP) min 0.85A.
Could you give absolute maximum ratings of PMID current ?
Will the chip BQ25125 work with the such pulsed current from battary ?

  • 0
    TI__Genius 12485 points

    Dmitry,

    1. You are correct, if you are using the TS pin and want to cut-off charging at 45C, the warm region could be pulled into about 30-35C. One workaround which i have seen is to raise VBATREG by 140mV when a warm fault is generated. However, are you using an over-voltage protector on your system? While I have seen this method being used, I always ask designers to think of situations where the MCU could be stuck etc., Optionally you could pair the BQ25150 with the TPS6280x device which allows you full programmability over the TS cutoffs.

    Warm and Cool Control:

    The TS event will generate a fault condition - Read the registers and check if the 0x02 bits B5 and B6 are in cool or warm- If so, raise the VBATREG - Poll the TS Control register and check for bits B5 and B6 to return to 00 - Change the VBATREG to original setting.

    2. Is the adapter present when this current is being pulled? If the adapter is present, the total current you can pull from PMID will be BATOCP + ILIM current. The BQ25125 should not have any issues supporting your current. However, I would check the battery impedance with any sense resistors you have to not cause a dip on the VBAT voltage on the pin itself when this current is being pulled. If that does happen, you might have to lower your BUVLO setting. 

    Let us know if you have any questions or have a schematic for us to help you review. 

    Regards,

    Gautham

  • 0 in reply to Gautham
    Prodigy 120 points

    Thank you very much