BQ24030: Tying System Load Directly to Battery

Antonio Fadhel

Part Number: BQ24030
Other Parts Discussed in Thread: BQ24070, BQ24072

Hi,

My customer is having issues with their bq24030 design because their system occasionally requires drawing battery currents higher than the 4A abs max. They are looking into disconnecting OUT (leave floating), and tying the system load directly to the battery. Do you see any issues with this configuration (pretty much using as a non-powerpath charger)? These are the drawbacks I already communicated to them:

• If the battery is deeply discharged, the system will not power on until the battery is charged beyond the system UVLO.
• The battery charge rate will be the programmed charge current minus the current being drawn by the system, so charge time might increase depending on the system.
• You have lower power from the charger since the system will not see the 5V/4.4V. The charge LDO will drop it down to the battery voltage.

Thanks,

Antonio

over 5 years ago

0 Anthony P Pham over 5 years ago

TI__Mastermind 23410 points

Hi Antonio,

Along with the reasons stated you could also mention:

(To supplement your third point) - Battery will also be discharged as the primary source unless it is disconnected and charged to above VLOWV (which then agrees with your second point)
(When system is connected to BAT) When VBAT is below VLOWV, the TS pin may not properly function, potentially not disabling charge correctly if the battery gets too warm.
(When system is conencted to BAT) the battery will only charge in CC mode (if the current is available). In Pre-Charge or CV mode, it will supply current.

Hope that helps.

0 Anthony P Pham over 5 years ago

TI__Mastermind 23410 points

Hi Antonio,

I noticed a similar question come in today and saw that the BQ2407X has an max OUT current of 5A if that is what is needed.

https://e2e.ti.com/support/power-management/f/196/p/883798/3268631#3268631

0 Antonio Fadhel over 5 years ago in reply to Anthony P Pham

TI__Genius 9410 points

Thanks, Anthony. I took a look but it seems like the devices with the same package/pinout (bq24070/1) have the same current rating as the bq24030, and the bq24072+ support the 5A but in a different package.

Regards,

Antonio

0 Anthony P Pham over 5 years ago in reply to Antonio Fadhel

TI__Mastermind 23410 points

Also, sorry the TS information may be incorrect. I'll fix and close the thread.

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BQ24030: Tying System Load Directly to Battery