BQ25185: BQ25185 input power pin requirements

Kaveh Mohammad

Prodigy 110 points

Part Number: BQ25185
Other Parts Discussed in Thread: BQ24075

Hi,

I was wondering if BQ25185 can be used with a solar cell connected at VIN input pin?

Thanks

6 months ago

0 Juan Ospina 6 months ago

TI__Genius 11925 points

Hi,

It can be used depending on the solar cell characteristics. What is your expected input voltage range?

Best Regards,

Juan Ospina

0 Kaveh Mohammad 6 months ago in reply to Juan Ospina

Prodigy 110 points

I have not chosen a solar cell yet. But it seems to me if I use a solar cell with this chip since there is no max power point tracking in this chip, if the load current is high, my output voltage will drop significantly. So the efficiency of the charging will significantly depend on the load.

+1 Juan Ospina 6 months ago in reply to Kaveh Mohammad

TI__Genius 11925 points

Hi,

The IC prevents additional current being pulled from the input if the voltage drops to the configurable VINDPM voltage. This prevents the voltage from collapsing to unusable levels.

Best Regard,

Juan Ospina

0 Kaveh Mohammad 6 months ago in reply to Juan Ospina

Prodigy 110 points

So in this case the additional current will be drawn from the battery?

+1 Juan Ospina 6 months ago in reply to Kaveh Mohammad

TI__Genius 11925 points

Hi Kaveh,

That's right. With a limited input current, additional load current will be supplied by first reducing charge current. If the load current is so high that charge current is reduced to 0, the device will enter supplement mode and begin to draw current from the battery in order to supplement whatever input current is available. Together Input current and Battery current will provide the power for the system load.

Best Regards,

Juan Ospina

0 Kaveh Mohammad 6 months ago in reply to Juan Ospina

Prodigy 110 points

How about BQ24075? Can this also run of solar cell as input power source?

+1 Juan Ospina 6 months ago in reply to Kaveh Mohammad

TI__Genius 11925 points

The BQ24075 has a non-configurable which means it may be more limited in the way in which it regulates the input's voltage. I know the BQ25185 has been used with solar cells previously but I'm not sure if the BQ24075 has. The BQ25185 has a BAT-tracking VINDPM option which will regulate the input's voltage to be high enough to charge the battery as the battery voltage increases (Input voltage must be greater than battery voltage in order to charge the battery).

Best Regards,

Juan Ospina.

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BQ25185: BQ25185 input power pin requirements